Monday, November 15, 2010

First Stage


We can already do, and have done, a great deal in space. We have scouted all the major planets, landed on the Moon, Venus, Mars, and Titan, and dropped among the clouds of Jupiter. We have passed through the heliopause into interstellar space.

The International Space Station has shown that crews can live and work aboard a spacecraft for years, with no emergency requiring evacuation to Earth or urgent support from Earth.

This is the primary requirement for human interplanetary travel. At a fundamental level, add a drive bus and you are good to go. Nor is any really major handwave needed for a solar or nuclear electric drive capable of reaching Mars in 2-4 months. (If Mars leaves you cold, adjust for the destination of your choice. It will probably be colder.)

All you need to wave is a check for $200 billion or so, to pay for developing your vehicle and mission from conceptual design to flight testing and human spaceflight certification.

Do not expect to get there for much less than that. The Airbus A-380 and Boeing 787 Dreamliner - commercial products of private industry, working in a mature kindred technology - each cost some $15 billion to develop. Such projects simply require an enormous amount of costly engineering work and one-off fabrication.

SpaceX and Scaled Composites do not prove otherwise. They prove only that the ecosystem has a place for small, agile skunkworks that can underpay top talent to work on exciting projects. Even technologies like 3-D printing won't really change the equation, because initial space costs are mainly engineering costs, and engineering at the cutting edge remains a craft trade.

But for a trillion US dollars or equivalent, give or take, you could probably build yourself a decent start on the classical rocketpunk midfuture: a second generation station with spin hab; outposts on Luna and Mars with ships to serve them; a human mission to Jupiter; altogether up to a few hundred people living in space. Call it the Clarke-Kubrick vision, though it could equally well be called the Ley-Bonestall vision.

The specifics are all freely subject to change. Commenters have challenged such rocketpunk-era verities as an orbital station as transfer point, and of course there are debates about where we should actually go and in what sequence. But this infrastructure, or something comparable, is the trillion dollar admission ticket to everything else.

A trillion dollars is a lot of money. More precisely it is a staggering, awesome, incomprehensible amount of money. It might end up being more than we are willing to spend on space travel in this or any century. But it is not impossible money. It is comparable to NASA's cumulative budget from its beginning to the present day, and about twice the cost of another public transportation system of similar age, the Interstate Highway System.

I am very doubtful that the private sector can or will take us into deep space on its own. But the largest corporations have revenue and market capitalizations of a few hundred billion dollars, so - given persuasive enough reason to believe that it would be profitable - it is not utterly out of bounds to imagine a global commercial consortium raising a trillion dollars.


The time scale of space is really, in large part, the money scale of space. If space spending in the later 20th century had remained at Apollo levels we might well have had the Clarke-Kubrick vision on schedule in 2001. At the levels of space spending and resulting space progress that we have seen over the last 35 years it is about in line with what we might expect for 2101.

It could as easily be 2071, or 2171. (Or never.) Given a sufficient (hand)wave of great power muscle flexing it might be 2031. But I will use 2101 as my conservatively optimistic benchmark. This presumes that we continue going into space in the same rather muddled, low-keyed, but persisting way we have since those heady early years.

So. At the start of the 22nd century, or broadly comparable date of your choice, we have regular interplanetary travel, but still very little of it, and what there is is very expensive.

Production jetliners, as I've often mentioned, cost about $1 million per ton at the factory ramp. But commercial jets can be sold for that price because Boeing and Airbus expect to build several hundred of them, spreading out the development cost and permitting semi-mass production efficiencies.

The first generation of interplanetary ships will be handbuilt prototypes. The second generation will still be largely handbuilt, though modular construction will begin to allow limited production runs of standard hab pods and the like. So a ship capable of carrying 10-20 people on an interplanetary mission, with departure mass of 1000 tons, dry mass 500 tons, gross payload 200 tons, might cost $5 billion assembled on orbit and ready for loading.

Adjust ticket prices accordingly. Suppose that your ship can make 10 round trips to Mars in a design service life of 25 years, so charge each round trip $500 million up front. Add another $500 million for 500 tons of propellant lifted from Earth - don't expect launch cost under $1 million/ton at the modest traffic volume of the early interplanetary era. And don't expect to get it from anywhere else, not at this stage.

So (simplistically!) $1 billion for our ship to make one round trip to Mars. It carries 20 people in transport configuration, so that will be $50 million, please. For a first class ticket $100 million - not for the caviar and steaks but the chef and stewards.

I confess a personal weakness for Pullman class interplanetary travel. The Realistic [TM] space travel alternative of doing basic preventive maintenance on microgravity toilets for 200 million miles would get old even faster.

But a note of practical caution to my libertarian minded readers. A world with so much loose money sloshing around the economic elite that it can send a Pullman car full of billionaires to Mars every two years is also a world with thousands of Paris Hiltons. Never mind poverty and social injustice. At some point sheer annoyance will bring out the guillotines.

Ahem, back to the point.

What happens after the early interplanetary era, in the second century or two of space travel, is much more conjectural, even by the necessarily naive standards of this essay.

Personally I think that by far the most likely human space future, through the 22nd century and well beyond - in short, through the midfuture - is far more like Antarctica than Heinlein: a chain of scientific and technological outposts, gradually extending outward.

Space is remote, costly to reach, difficult to live and work in, implacably indifferent to human life, and filled with things that fascinate us.

It is probably not filled with McGuffinite.

The human Solar System may well belong to artists, not writers. A deep space effort like this provides all of the lovely images - dawn on Mars, gliding through the rings of Saturn, everything Chesley Bonestall imagined and more - but not many plot lines, and certainly not the favorites among this bloodthirsty audience.

Which might be a feature, not a bug: a Solar System touched more by our aspirations than our failings.



That is probably not what you want, but I will save other possibilities for another post.


The image of an ESA concept for Mars exploration comes from a Romanian space website.

228 comments:

1 – 200 of 228   Newer›   Newest»
Geoffrey S H said...

I wouldn't say it is not what we want... just that it can make occasionally for difficult stories.

I mean non-military as well as military.

Writing about a frieght craft pilot learning the ropes.. or social comnflict and interaction between those maintaining Mars orbiters while on the low orbit trasnsit station.
Explorers creeping between the ice-sheets of Europe to accompany the robots to see what's there...

Problem is, the pilot will have learnt the ropes on Earth, not "out-there", and all will be done to prevent any problems beforehand, thus putting a story about learning and solving problems in space simply makes no sense. Any mission outcome not 100%satisfactory simply will not go ahead. As for social bonds forming, ties among the crews I suspect will be avoided- you do not want to risk an form of conflict, no matter how minor on such a long mission. Cold and proffessional talk will be all that takes place. even if there is smalltalk- that's all. No payload available for games to pit each other against, few books, if any.

No humans with the robots, and we probably won't find anything truly different or spectacular down there (on Europa) anyway- certainly nothing to do anything useful with.

No rescue missions, no pressing social issues that need to be solved, no great discoveries.
Nothing. Possibly not even much conversation.

Just afew multiple stage launches carrying scientists off to a small station somewhere to moniter computers that do the majority of scientific work.

I'm happy to not do military themed stories- that's an ambition of mine. Its just that the non-military offers so few opportunities as well. No trade runs or impressive diplomatic meetings in space.

That's alittle depressing.

Robbie said...

Well I think the quickly dwindling resources on this planet will kick our asses in to gear. See, that's what happens in the Killzone story. There's a nuclear 3rd world war over the remaining oil, and the world's leaders realize that humanity will go extinct if this keeps up. So the surviving nations ban together to form the United Colonial Nations, and start a massive space program to first colonize the Solar System, then go to other stars.

Hopefully in reality it won't take a 3rd world war get us heading in the right direction. But who knows?

Geoffrey S H said...

Unless we go the way of 100% recycling. Population reduction can also take place... given the altenatives, surely some people would want to abstain having more than 1 child to save the planet. There is some proof for this occuring- Wrigely and Schofield in the 1960's acertained that population stagnation in England in the 14-1600's might more be due to couples not having children than to people starving in the classic malthusian assumption.

Unforetunetly there is simply not enough evidence to prove this entirely right... but nevertheless, the whole "scarce resources" and "overpopulation" I don't compltely buy. Even if it is true, then with all the will in the world, we don't have the capability to solve that through space travel and cosmogratuion alone. Thus, we MUST find others ways to solve our problems.

If we do, then space is no longer a neccessity.

Urgh, I hate playing the heretic.

Dex said...

So, let's take a look at events in the very near future, ie prior to 2031!

In the next 5 years (ie by the end of 2015), it is likely that two American companies, SpaceX and Boeing will have manned launch vehicles capable of lifting 6 or 7 people to LEO.

Bigelow Aerospace (BA) intends to assemble a station on-orbit with room for up to 15 people (1 Sundancer, 2 BA330s). This station requires the presence of at least one of those launch vehicles. It also introduces a manned launch rate of 1 launch/month and likely 1 supply mission/month.

This is a single station.

By 2020, it is feasible to have an additional, larger BA station with room for up to 24 people. Total of 39 people at anyone time. And these BA customers need not have trained together or even talked to each other before inhabiting the same station (but not the same hab).

By 2031, near-Earth space could have several stations inhabited by multi-cultural customers from LEO to the Moon.

Native Jovian said...
This comment has been removed by the author.
Anonymous said...

If you don't want warfare in space, then use interpersonal conflict; spending a year in a tincan trying to avoid developing ANY sort of personal relationship with your crewmates is a sure way to wind up duct taped to your bunk for the duration of the trip. As for ramping up space travel, I don't think you can assume a steady trend; most endevors are periods of rapid advancement followed by 'plateaus', that are once again followed by periods of rapid advances' this cycle continues until the technology or market reaches maturity. Right now, the space industry is in a plateau (although there is evidence of another round of innovation on the horizon), but this won't last forever. I hope. Yes, $1 trillion is a ginormous amount; but if spread out over a century, not so much. Besides, you send a scientific expedition someplace, someone will figure out how to make money from it. That allows better equiped/more efficent/better financed expeditions...that someone will figure out how to make money from. It may not be a logical, or obvious leap from what the expedition finds to what someone back on Earth comes up with...

Give someone a dream of frontier and they will build an empire to gain that dream...

Ferrell

Native Jovian said...

Well I think the quickly dwindling resources on this planet will kick our asses in to gear.

That's very silly. If we ever do hit the point of rapidly dwindling resources (which is by no means a given -- humanity is brilliant at coming up with new ways to do stuff), then where will the resources required to colonize space come from? If the planet is closing for business, then the standard "humans are stupid bastards" assumption (stupid because we ruined our only planet, and bastards because some people like to think of humanity that way) demands that we fight a pointless and hugely destructive war over the remnants, not suddenly unite in a glorious spacefaring union.

Rick said...

Welcome to a new commenter!

The idea is not silly (and I ask everyone to resist such comments). It is, alas, problematic.

Suppose that a ship is sinking, entirely due to irresponsible officers and an undisciplined crew. The problem is not simply to get their act together to launch the boats, or even build boats out of deck chairs, but to build a new ship.

Regarding literary tropes, it is a curious fact that Hollywood has made two popular and critically acclaimed historical period pieces about the actual space program. Three if you count October Sky. Real space travel may, in human dimension, be more interesting in retrospect than in prospect.

Thucydides said...

Several issues to take here:

1. The price tag of a trillion dollars is not reasonable at all. Robert Zubrin explores this issue in "The Case for Mars", and even suggests that the actual cost of Mars Direct could be as low as $5-6 billion dollars. Cost plus accounting encourages the explosive growth of overhead to suck in the greatest amount of taxpayer dollars, and the corresponding growth of government bureaucracy to "supervise" these contracts.

A sort of checksum can be had by looking at the "Skunkworks". They produced the F-117 Nighthawk in 31 months for a flyaway cost of @$50 million/plane by being small, focused and relatively unconstrained. A sophisticated, high performance airplane was created quickly and at low cost (contrast to the escalating costs and delays for the F-35 Lightning II).

2. Population pressure is working in reverse these days, as the West, Russia and China suffer from demographic busts. The issue for the next half century will be declining work forces having to pay for past entitlement spending.

3. Resource depletion is countered by bringing formerly uneconomic sources into production, and substituting new materials to replace the old. Whale oil was replaced by petroleum in the 1800's (it was useless gunk before then), coal replaced wood and charcoal as fuel in England starting in the 1600's when fuel usage outstripped the ability of forests to regenerate and sand is replacing copper as optical fibre replaces electrical wire for communications.

The spaceships are still somewhat beyond single company’s resources, and there still is a need to identify the drivers that will bring investors and settlers into space, but private exploitation of LEO and cis lunar space is a plausible expectation in the midfuture. I would suggest the driver of any large scale settlement would be the desire to escape the restrictions of Earth to practice social, economic or religious preferences free of interference. Self contained settlements which have little need for contact or trade with Earth or other settlements might be seen as a feature rather than a bug in this scenario.

For trade based scenarios, the only plausible McGuffinite would be 3He, with all the problems and issues that brings. The plausible midfuture is not Rocketpunk friendly!

Elukka said...

The point at which space may be a viable solution to dwindling resources is not when you've run out, but when you realize that you're going to run out in the near future. So you need to do something, and in some cases space could be the answer.

Milo said...

For comparison, the Gross World Product - roughly, the total amount of money made anywhere in the world - is $70 trillion per YEAR. Remember that the majority of that is not spent on space travel.



Geoffrey S H:

"As for social bonds forming, ties among the crews I suspect will be avoided- you do not want to risk an form of conflict, no matter how minor on such a long mission. Cold and professional talk will be all that takes place."

I disagree. People aren't going to spend that long together without getting to know each other, and if they do then they're being actively passive-aggressive.

All proposals for long-term space missions I've seen have involved making the astronauts spend some time together while still on Earth (probably in training) to ensure they get along well.


"No payload available for games to pit each other against, few books, if any."

That's where computers come in handy. Video games and digital books don't take up mass, and you can download new ones if your bandwidth permits.



Robbie:

"Well I think the quickly dwindling resources on this planet will kick our asses in to gear."

...Quickly dwindling resources? We still have more fossil fuels than Mars.

The main resources to be found in space are rocks and ice, of which we are not expecting to run out in the near future. Space mining has been proposed for the production of objects meant to be used in space. If you plan to do something in space (such as colonizing a planet), using local resources will make it much easier, but first you need a reason to be in space in the first place.

destop said...

Wow, thank you for this nice account of what the future of exploration could be. I particularly like the vision of SpaceX and Scaled Composites as "skunkworks that can underpay top talent to work on exciting projects". And I wondered if it was not also a part of the failing space programs. Are we sure that the top talents work in the aerospace industry? I know some very talented engineers who started on some space programs. But after a while, they gave up because, although they had a lot of dreams and motivation, they could not support the conditions at work anymore.

Robbie said...

What I would like to know is why no one has built any rocket sleds yet? It would be a much cheaper, and not to mention much safer way, to launch spacecraft.

Hey Rick, why not in a future post talk about rocket sled launching?

Jedidia said...

What exactly do you consider a rocket sled? a rocket driven catapult that goes up a mountain? you have way better efficiency by taping the rocket to the payload directly instead of a sled, you know.

But maybe I'm just too misinformed and don't know what a rocket sled is. Could you explain the concept a bit?

Citizen Joe said...

All of this presupposes an astronomical amount of money, much of which is spent on research. That research costs that much because that is how much people are willing to pay the engineers and scientists. If you look at programs with shoestring budgets, they find ways around that. For example: I believe that one group is parsing out data to volunteers to use their downtime on computers to process star scans (or something like that). We've got like 7 trillion people on this planet. If we can get even 50 cents out of each of them we'd have enough. The trick is to get the costs down by asking little from many so that they can't feel the impact.

Rick said...

Sleds. Back in days of yore, Heinlein had a sled going up Pike's Peak, serving as the zeroth stage for rocket powered SSTO shuttles.

In modern times sleds are discussed mainly or exclusively for airbreathers. The idea is to whomp them up to ramjet ignition speed, so that the vehicle does not need complex turbo-ramjets, nor the wing area needed to carry a full fuel load at conventional takeoff airspeeds.

The problem here is not the sled, but the whole concept of airbreathers. They have to fly through enough air to avoid flameout, and sustained hypersonic flight produces a BRUTAL heat soak.

I love the idea of flying to orbit - note the 50s style ramjet shuttle in my blog header image. But it is very challenging, and not really needed for the traffic volume of the early interplanetary era.

When we can build entire airframes out of Super Carbon Nano Stuff, then we can look at airbreathers.

Anonymous said...

I don't have much to say, right now, except for Rick wanting to send Paris Hilton to Mars and Citizen Joe thinking that there is a thousand times the amount of humans says a lot more about them than about the Rocketpunk future.

Seriously, however, I believe that rocket sled launch is the concept of using a rocket sled to launch an air-breathing second stage that in turn launches a rocket powered final stage. It has to do with reducing costs and building in a degree of reusability (I know some of you are oppossed to reusability, but I'm just explaining the concept).

I think that the currently prevailing model of the space industry may be ready to change; the way we build, finance, manage, launch, and conduct space operations (seems to many) to have stagnated over the last 35 years or so; with SpaceX, Scaled Composite, Bigalow, and the like wanting to create their own market and operating model and get away from the way the big space companies do business; it is no wonder that so many people are eager to find a way to increase space travel/access through improved launch technology and/or reducing launch costs.

Several times we have talked about something on this blog only to have reality catch or pass us only days or weeks later. Sometimes the future isn't as far away as we are sure it will be, but many times it is much farther than we are hoping for it to be.

Ferrell

Anonymous said...

Drat! Not fast enough on the posting! Anyway...perhaps using a modified rocket sled launch concept for smaller commercial launches that are higher tempo then manned or big scientific payloads might reduce costs over a long period of time, as well as allow research on the best way to use mixed technologies in launch operations.

Ferrell

Jedidia said...

In modern times sleds are discussed mainly or exclusively for airbreathers. The idea is to whomp them up to ramjet ignition speed

I suppose you mean Scram jets, not ram jets, since a ram-jet can comfortably ignite at zero velocity.

Hmmm... So catapulting a plane up to scramjet speeds (somewhere around mach 2, but depending on a whole lot of factors).

The most obvious disadvantage of rocket sleds would then be that they have to operate in the dense lower atmosphere. It's a pretty challenge to reach that speed at low altitude, plus you're having ground friction on the sled which further reduces efficiency. I think if we had a Plane that can make it from scram-ignition to orbit in one go (by far not impossible, we got pretty much the neccessary technology, but it is untested and the design will still be a major engineering feat), I still think it would be far more efficient to strap a solid booster to it for the initial kick (think JATO, just... bigger. And probably ramp-launched, not runway launched).

The advantage of such a setup is that not only can it give you speed, but also a solid starting altitude where you can really use the scrams. It is no nice thing flying at mach two to three in the very low atmosphere, where you will still be even if your catapult goes up mount everest.

Rick said...

Money and cost.

Remember that my trillion dollar figure is for a full early interplanetary infrastructure - launch facilities, shuttles, orbital station, a constellation of operational lunar and interplanetary craft, Moon and Mars bases, and a Jupiter mission. Or variations thereon, plus a number of years of operation as everything is brought online.

Regarding Zubrin's estimate of the cost of Mars Direct ... when space advocates talk money, a safe general rule is to hang onto your wallets. The greatest space advocate of them all, von Braun, set the example for all the rest: His cost estimates were laughably lo-balled.

Certainly a well run program will end up cheaper than a poorly run one. Take my $1 trillion as anchoring a range: $500 billion if done well, $2 trillion for a fail if done poorly.

There are some scaling laws that probably apply to skunkworks. An operation of 100 people can dispense with most internal bureaucracy, an operation of 1000 people cannot.

In any case my cost estimates are based on the experience of commercial industry, $10-20 billion to develop an airliner that modestly extends the envelope of a well established tech.

A Mars ship will be on the same order of size as those aircraft, much more complex, with a much more demanding mission. And it must be built without the experience base we have from building and flying some 20,000 big multi-engine jets since the 1950s.


As for paying for it, a program on this scale can be paid for, over several decades, the way space programs have been so far - a combination of modest but broad public support for the coolness of space travel, along with national vanity and parochial economic interests. No McGuffinite is required!

I expect that the role of private business in space, for a long time to come, will be much what it already has been. Private firms will actually build most of everything, but the profit motive will follow rather than lead. Because until the heavy lifting is done, no one will know what, if anything, might be profitable Out There.

Tony said...

Thucydides:

"1. The price tag of a trillion dollars is not reasonable at all. Robert Zubrin...

A sort of checksum can be had by looking at the "Skunkworks". They produced the F-117 Nighthawk in 31 months for a flyaway cost of @$50 million/plane by being small, focused and relatively unconstrained. A sophisticated, high performance airplane was created quickly and at low cost (contrast to the escalating costs and delays for the F-35 Lightning II)."


The F-117 is a single seat ground attack aircraft, not a fighter. Also, if it failed in flight, the pilot could always jump overboard. Those aren't features of a manned Mars mission.

Zubrin...Zubrin -- have you ever met him in person? That dude is trying to sell you something. And I mean that with all of the negative connotations that one can rally to that statement. He's smart, and he's advanced the state of the (strictly conceptual) art. But...he's trying to sell you something.

Tony said...

Rick:

"I expect that the role of private business in space, for a long time to come, will be much what it already has been. Private firms will actually build most of everything, but the profit motive will follow rather than lead. Because until the heavy lifting is done, no one will know what, if anything, might be profitable Out There."

And this is the $ quote. Apropos of Unstoppable having been released in theaters over the weekend, for many decades to come running a space program is going to be much like running a national railroad. Contractors and suppliers will make a lot of money, but the railroad itself is a public service. (Ticket and freight revenue is just a hidden tax, and hardly covers all of the costs.)

Which is not a slam on 21st Century railroads, public or private. The money in railroading has always been in building the things and supplying euqipment. Running a railroad is a good way to lose your shirt.

The same applies to space travel -- contractors can control their own costs and make a profit. The people buying and running the equipment...not so much.

(And let's not get into the demonization of cost-plus. Without cost-plus accounting, nobody would get into highly speculative ventures like building a new rocket or spacecraft. Nobody can reliably estimate costs for those kinds of things.)

The other thing that Rick tiptoes around, but still can't quite bring himself to come right out and say, is that Romance and space travel just aren't meant for each other. Manned spacecraft are too expensive and rare to actually use them for war, and their crews will likely be too emotionally distant from problems on Earth to fight each other. (Something Hollywood got exactly right in 2010) Your crewmembers had better get along with each other. When sh!t goes wrong, Hollywood will make a movie about it, especially if the plucky crew and the steely-eyed missile men pull it out in the end. But, when you wrap it all together and tie it up with a bow, there's no room for adventure in space.

Tony said...

Addendum, Re: unadventurous space future

Gene Cernan loves to point out that when he was on the Moon, he had a house and a job. Now, that's a bit subversive -- and maybe even picaresque -- in the context of a multi-billion dollar government program, but it makes an important point: routine, boring crap is a good thing in spaceflight.

tkinias said...

Geoffrey S H:

but nevertheless, the whole "scarce resources" and "overpopulation" I don't compl[e]tely buy.

Back in the 1970s, the Club of Rome modeling work suggested that the big problem was overshoot. Taking population as an example: If people perceive that there is a scarcity of resources, they tend to have less children. But it takes a generation for that to have effect, and during that time things continue to get worse. Not to mention that people only tend to notice a problem once it becomes sever. The big fear, then, is that fertility reduction comes too late to prevent overshoot and collapse.

Most demographic models now have world population peaking this century, somewhere in the neighborhood of ten billion. The rate of growth is coming way down, even if it will remain positive for some time yet; we’re not likely to be dealing with the global population tripling or worse, as a simple projection from twentieth-century growth would suggest. But we may already have overshot: by some models, the population sustainable in the long term is more like three billion.

tkinias said...

Damn. Meant to hit preview, not publish!

Anyway, to conclude: How could overshoot-and-collapse lead to going into space? It’s often been argued that the Black Death of the 1300s was a spur to the Renaissance. The mechanism ‒ and whether there is a link at all ‒ is hotly debated. But we do know that there was a massive demographic catastrophe (maybe 50 percent average fatality rate across Europe), and a couple of centuries later we have an entirely different world with a rather different set of cultural values. It’s not inconceivable that the long-term outcome of such a collapse would be a global society willing to allocate a lot more resources to going into space.

Just a thought...

Anonymous said...

So ... it is good to know that we COULD do it ... and probably WILL do it as soon as someone comes up with a good reason WHY we should do it, a reason that is politically supportable in one or more industrialized nations.

tkinias said...

Tony:

routine, boring crap is a good thing in spaceflight.

Quite right. And that is a problem for mission planners and an opportunity for fiction writers.

“Highly exciting operation” is very rarely a design objective for an engineering project. Increasingly, mature designs and (especially) automation make things like flying airliners pretty boring; aerospace and military folks are starting to get concerned with the effects of boredom on crew alertness. It just doesn’t take much crew attention to get a 767 from A to B, unless something goes wrong. This problem will be multiplied in space, because we’re talking not only about much more sophisticated automation but also about missions lasting months instead of hours.

This may be where military-style discipline becomes necessary. Crew will not want to spend their time doing make-work that the computers or robots can do better, or at least easier, but they have to keep actively engaged in running the vessel to stay alert. Once discipline breaks down, nobody notices that an automation failure has let half your reaction mass boil off into space until it comes time to start the deceleration burn...

That constant tension between boredom and keeping alert, or the consequences of letting boredom win, are fertile ground for storytelling.

tkinias said...

From Rick’s original post:

A trillion dollars is a lot of money. More precisely it is a staggering, awesome, incomprehensible amount of money. It might end up being more than we are willing to spend on space travel in this or any century. But it is not impossible money. It is comparable to NASA's cumulative budget from its beginning to the present day, and about twice the cost of another public transportation system of similar age, the Interstate Highway System.

I don’t want to get into American politics here, but I have to mention the War on Terror. Joseph Stiglitz (Nobel laureate in economics), in a 2008 book, estimated the total cost of the U.S. war at around $3 trillion. I haven’t read the book, so I don’t know all the breakdown, but it seems that $1 trillion in direct cost to the U.S. Treasury would be a pretty conservative estimate.

This pretty clearly demonstrates that, given the political will to do so, a wealthy country can do a decade-long, trillion-dollar project. The U.S. may not have the capacity for another such effort any time soon... but it means that the level of funding is nowhere near absurd for a hypothetical near-future endeavor.

Milo said...

Citizen Joe:

"We've got like 7 trillion people on this planet. If we can get even 50 cents out of each of them we'd have enough."

That's 7 billion people, not 7 trillion. So you'd need 500 dollars per person. Now consider that many of those people are dirt poor and don't have 500 dollars...



Rick:

"An operation of 100 people can dispense with most internal bureaucracy, an operation of 1000 people cannot."

So can we divide our workforce into groups of 100, and have bureaucracy only for intergroup coordination?

One bureaucrat per 100 real workers doesn't sound too bad.


"a combination of modest but broad public support for the coolness of space travel"

Like so many things, most people enthusiastically support space travel right up until the point where you tell them they'll have to pay for it.



Tony:

"Manned spacecraft are too expensive and rare to actually use them for war, and their crews will likely be too emotionally distant from problems on Earth to fight each other."

That depends on travel times and travel costs. Luna is close enough that a base there might well have significant interests with Earth. Mars can be reached in a couple months with a good fission-electric engine, which has provably been fast enough for people to fight wars in the Age of Sail - if they have something to fight over. The gas giants are far enough away that they'll be essentially completely isolated without some very powerful fusion (or nuclear saltwater) rockets, but the individual moons of each system are very close.

Of course, it also depends on the size of your colonies. A colony of a few thousand people pretty much can't send a force large enough to meaningfully threaten Earth, and those people are temporary workers who are only there on a six-month shift, they're unlikely to want to spend four of those months fighting a war. If you have large permanent colonies, though, it's not unreasonable for them to find something to fight about eventually.


"routine, boring crap is a good thing in spaceflight"

As the Chinese blessing goes: "May you live in uninteresting times."

But what's desirable from the point of view of the people on the ship is not necessarily desirable from the point of view of a reader or writer.

And just because routine, boring crap is a good thing doesn't mean that it'll always happen...

Tony said...

Re: tkinias

The "asleep at the switch" trope has acouple of problems as a plausible midfuture plot device:

1. Really critical evolutions in spaceflight are so out of the ordinary of everything else going on, that the people involved are alert and paying attention.

2. Even if you could figure a way in which to use this trope, you're asserting to the reader that the guys who were so inattentive (or just poorly disciplined) to let the Bad Thing happen are the same ones that are going to save the day. Heavy Reality Dissonance ensues right about here.

Also, the idea of military discipline is a bit overdone by most SF writers (except for the ones who have actually been in the military). Spend six months at sea -- or six months in space -- on ship, and see what portion of that can be accomplished with clenched jaw an a stern vissage. Some of the funniest interpersonal episodes I have ever witnessed happened after being at sea for several weeks on a naval vessel. It turns out that one of the best ways to conquer boredom is to throw the book of normal civilized behavior out the window and just go slightly nuts for the duration.

The people that made Das Boot actually did a pretty good job on this. The way the submarine commander tolerated and at times even embraced the eccentricities of his crew is almost a textbook example of how to manage the shipboard situation. Nota bene: this may not bode too well for the future of flight crew selection on the NASA model. US astronauts are wrapped too tight to be truckers IN SPACE!, or even good u-boat crewmen.

Still, a lot of good plot fodder could be found in the coping mechanisms of flight crew and passengers...if one knows what can happen, and how. Verisimilitude is hard to achieve without either personal experience on the author's part or good technical advice.

As for what wealthy societies are capable of doing, one has to remember that the WoT is still perceived as an existential issue by a mjority of Americans. That's where the trillion dollars comes from. It won't be that way with spaceflight, ever.

tkinias said...

Milo (quoting Rick):

"An operation of 100 people can dispense with most internal bureaucracy, an operation of 1000 people cannot."

So can we divide our workforce into groups of 100, and have bureaucracy only for intergroup coordination?

One bureaucrat per 100 real workers doesn't sound too bad.

It don’t think it quite works that way. I’m not sure I would say that even a 100-person organization can do without structure. The rule of thumb is a span of command of five: i.e., you can effectively direct the action of five people, no more. That means that a 100-person organization, optimally, has three tiers of leadership; a 1000-person organization has five.

But let’s say that the supervisory levels within a 100-person organization don’t count, as they’re pretty close to the work being done and so cause negligible bureaucratic friction. Any way you assemble your “pure” 100-person work units into a whole, you still need roughly one manager per five units, one supermanager per twenty-five, etc.

Tony said...

Re: Milo

In the trillion dollar, hundred year future proposed in the opening, there aren't going to be enough people in space to make it strategically significant.

Robbie said...

Check out this site, it goes into depth about rocket sleds: http://www.g2mil.com/skyramp.htm

tkinias said...

Tony:

Even if you could figure a way in which to use this trope, you're asserting to the reader that the guys who were so inattentive (or just poorly disciplined) to let the Bad Thing happen are the same ones that are going to save the day. Heavy Reality Dissonance ensues right about here.

I’m not sure that follows: a story could be about the heroic rescuers who have to save the bored-sloppy folks... or it could have an antihero who gets half the crew killed by being bored sloppy. I agree that if the ones who let Bad Things happen also save the day, dissonance may ensue.

Also, the idea of military discipline is a bit overdone by most SF writers (except for the ones who have actually been in the military). Spend six months at sea -- or six months in space -- on ship, and see what portion of that can be accomplished with clenched jaw an a stern vissage.

Ah, I think we’re talking about two very different definitions of discipline. I concur totally about the irrelevance of clenched jaws and stern visages. By military discipline I meant that “I think the deck looks pretty clean already, Chief” is not an acceptable response to an order, and that refusing an order has potential consequences more severe than being fired.

Tony said...

tkinias:

"I’m not sure that follows: a story could be about the heroic rescuers who have to save the bored-sloppy folks... or it could have an antihero who gets half the crew killed by being bored sloppy. I agree that if the ones who let Bad Things happen also save the day, dissonance may ensue."

I'm still not buying, for the simple reason that everyone is watching eveyone else all of the time, because they're all in the same boat. This is at the very root of modern, post consciption/press-ganging naval discipline.

"Ah, I think we’re talking about two very different definitions of discipline. I concur totally about the irrelevance of clenched jaws and stern visages. By military discipline I meant that “I think the deck looks pretty clean already, Chief” is not an acceptable response to an order, and that refusing an order has potential consequences more severe than being fired."

Why is everyone in Star Trek (TOS) an officer, and pretty much treated that way by everyone else, from the admiral on down? Because that is a demand of spaceflight, and Rodenberry recognized it. There aren't going to be any mess cooks or compartment cleaners on a spaceship any time soon. Everybody, including the passengers, is going to have a real profession. Maintenance is therefore going to be done by everyone, the nominal captain included, as a part of their duty to the ship's complement as a community.

Shipboard society in general will be much more like a wardroom without a crew to supervise than it will be like anything else. Yes, there will have to be a captain, and everybody else will be formally subordinate for certain evolutions or purposes, but it will still be a community of peers. You don't tell a PhD astrophysicist that he had better get his ass in gear with the swab. He either does it because it's the right thing to do, or because peer pressure makes him do it.

Oh, and everything I said earlier about psychological coping mechanisms still applies. Everything I observed about the social dynamics of shipboard life comes from membership in three different highly informal, but altogether real, sergeants' messes onboard ship. (US Marine culture doesn't have the formal messing tradition at the NCO level that Commonwealth contries do, but aboard ship NCOs tend to be berthed together and spontaneously form communities that are indistinguishable from more formal messes.) I can tell you things about peer communities coping with claustrophobia, isolation, and other stressors that no psychologist knows, or will ever know, because none of them go out to sea for a long enough period of time.

Rick said...

There is nothing new about these tropes on a micro level. Clarke and Heinlein both stressed the boredom of routine spaceflight, and the fact that every human effort was made to keep spaceflight routine at all time.

The problem for us space opera hacks is at the macro level. The great powers of 2101 could probably build interplanetary laser stars if they wanted to, but there is very little reason they would want to. To plink the other side's research outpost on Europa?

Likewise with politics. The only space politics in anything like the grand sense will be entirely on Earth.

Again, basically think Antarctica. It is not a place associated with picaresque adventures, except for fanciful settings like a Bond villain's secret base.

tkinias said...

I was just thinking some more about the question of scaling and bureaucracy. Using the 5:1 rule of thumb for span of control, the proportion of leaders to workers quickly approaches (but does not exceed) 20%: for a team of 6, 1 leader; for a team of 31, 6 leaders at two levels; for a team of 156, 31 leaders at three levels; for a team of 781, 156 leaders at four levels; for a team of 3906, 781 leaders at five levels; etc. That means that the bureaucratic burden actually does scale almost linearly.

I would hazard to guess that our sense of large organizations being burdened by excessive bureaucracy has more to do with the distance between the workers and the top leadership than with the proportion of labor being “wasted” on management. A worker in a 100-person organization has only two people between himself and the top; in a 10,000-person organization there are five. And that means that it takes longer for information from the floor to get up to the executives...

tkinias said...

Rick:

The problem for us space opera hacks is at the macro level. The great powers of 2101 could probably build interplanetary laser stars if they wanted to, but there is very little reason they would want to. To plink the other side's research outpost on Europa?

There’s been some interesting research on the economics of Victorian-era colonialism. One of the findings of economic historians has been that colonies were probably a net drain on the colonial powers’ treasuries. So why did they acquire them so rapaciously? Obviously intangibles like “national honour” etc. come into play, but there were still economic motives at work. Even if the colonies were not profitable to the state, there were influential groups that privately profited quite handsomely.

How is this relevant to space? It may not make economic sense to go into space in a rocketpunk way for the society as a whole, but there are certainly those who would benefit. If those who would benefit are sufficiently influential, public support can be orchestrated without there being any real overall social benefit.

And that applies to the militarization of space, too. Does it make sense to keep twenty laserstars in service? It does to laserstar manufacturers... BTW, Senator, how are you going to deal with the laserstar gap? The Chinese have thirty laserstars, you know...

Tony said...

Re: bureaucracy as an exercise in span of command/control

Five subordinates per supervisor is a theoretical optimum for organizational flatness. It is rarely how things are organized. In fact, in most settings it would be regarded as ridiculously hierarchical. Many corporate departments have 100+ employees adequately managed by a department boss and a few assistants. The bureacracy starts at the level of the department head, because he's the guy that has the Policies & Procedures manual on his bookshelf, he fills out the forms required by corporate superiors or other departments, and he makes all of the non-technical, housekeeping type decisions. In fact, what many people perceive as bureacracy is not hierarchical difficulties, but the web of duties and responsibilites between departmens at various levels.

And, as we all should know, the complexity of an organization is proprotional to the square of all the interdepartmental interfaces. Increase the number of departments by ten, you don't increase organizational complexity (i.e. bureuacracy) by a factor of ten, but by a factor of 100.

Rick said...

I don't think organizations are simple replicating teams of five. At some point, roughly on order of 100, line and staff begin to appear, with people around the honcho who don't manage anyone but have senior manager status. At some larger scale you get divisions with their own staffs.

General rant that bureaucracy is universally but carelessly maligned. Bureaucracy is the main human software of the Industrial Revolution. The business corporation as we know it is basically a legal framework for a private bureaucracy. It was created because railroads are inherently bureaucratic organizations, and have to be.

The free market will not schedule your trains for you; for that you need a bureaucracy.

It is an odd fact that so many people implicitly accept the role and necessity of military bureaucracy, but are shocked, shocked by its civilian counterpart.

Space travel, certainly through the era I am describing and well beyond, will be almost entirely a bureaucratic enterprise. Too many people have to cooperate too closely for it to be anything else.

This is what 'quasi military' organization means. But I would take it a bit of a different direction. Space travel is, in some fundamental sense, a 'church' activity. An interplanetary exploratory ship has characteristics resembling a Benedictine monastery with a drive bus attached.

blogs.echofiveecho.com said...

tkinias:

"And that applies to the militarization of space, too. Does it make sense to keep twenty laserstars in service? It does to laserstar manufacturers... BTW, Senator, how are you going to deal with the laserstar gap? The Chinese have thirty laserstars, you know..."

It applies to Earth-focused operations. And we can already see that it doesn't lead to the Cold War IN SPACE! It's just too damed expensive for that. Heck, getting money out of Congress to make replacements to the GPS constellation (both on-orbit spares and the system as a whole) has proved to be like pulling teeth from and angry hippopotamus.

As for the general case, please review my earlier comments about economic parallels between space programs and state railways. I'll add to that a political parallel -- people spend money on this sort of thing when it's perceived by enough people to be in the direct national interest. With railroads it's not hard to make the case. With space, even for military applications, even for applications on which major portions of the economy depend (e.g. GPS)...not so much.

Tony said...

Rick:

"General rant that bureaucracy is universally but carelessly maligned."

My turn to plead, "Not guilty, sir." :-P

Bureaucracy was an essential development on the road to a technological lifestyle. Without it, we would be stuck on late 18th Century industrialism. Thanks, but I think I'll be having my teeth drilled that day -- it'll be a lot less painfull.

Speaking of railroads, not only did they make the trains run on time, they invented our modern concept of time as a definite dimension of everyday life. Yes, it can be a tyranous dimension at times (hehheh, I used "time" to talk about time, hehheh), but it's also one that makes all of this technology we take for granted possible. You have bureaucracy to thank for your pocket computer/phone, which is a device that simply could not work without a universal concept of coordinated time. So there.

Rick said...

We must not, cannot, and will not permit a laser star gap!

The hitch is that an arms race can only develop if someone goes first, and there is no reason to go first. Being the only power with an interplanetary laser star gives no significant leverage.

Also, a point commenter francisdrake made on the Space Patrol thread, from political perspective ordinary interplanetary transports are equivalent to laser stars. They do not need armament to be impressive, or to create an economic interest in building more.

Rick said...

Almost universally!

Raymond said...

Weeellll...as the ground warfare thread theorized, throw up enough laserstars and bombardment platforms and you can get a pretty big groundside advantage...

Fernando said...

When I read about the International Space Station I thought: why don't we just stick a drive somewhere and a power plant, and BAM! instant cislunar spaceship. Obviously I'm sure there are some serious problems with this idea, but think about it: The ISS is already in LEO and I don't think it would require too much fuel to lift it to a higher orbit. The ISS is already manned, has "docks" where lunar landers could be fitted, has a life support system and doesn't need to be aerodynamic... no friction in space. The only things we need (as I see it, I'm not an engineer, just someone who spends too much time reading science fiction) are propellant and fuel thanks and of course the drive (chemical rockets?) and maybe a better power-plant (the ISS is supplied by solar panels... I'm not sure if those could power a flight to say, the Moon)
I know there will be various problems with my theory... as I say earlier I'm not engineer. But if we got a spaceship without a motor simply sitting there in orbit, this concept would require some consideration.

Rick said...

Laser stars in Earth orbital space could have a mission, but there is no reason to fit them for interplanetary travel. Or with hab pods and crew. An orbital laser star is basically the Hubble telescope with a bad attitude and an ample onboard power supply. Make it robotic and service it periodically on orbit. Or simply send up replacement pods, whichever is more expedient.

Real world militaries, as Tony noted, are notably unromantic about space travel.

At least in the US it is because of a tacit realization that if we have significant human military space travel we will soon have a Space Force, and every existing branch will have to make room for it at the table.

I don't know how it is in Russia. It could be much the same thing, or it could be that the Russian military is basically owned by tankers, who want nothing from space but the positions of the other side's tanks.

Raymond said...

Rick:

Yeah, I know. I was mostly remarking on the idea that the laserstars may come before the interplanetary drive buses. How that would fit into the overall expenditures, I don't know (shortsightedness about the GPS system aside).

Rick said...

Developing a suitable class drive bus for cislunar space is a very major project, and the ISS is a zero generation vehicle. By the time we're ready for that sort of mission we would want a new hab section for it, building on experience.

I regard the ISS, like Mir before it, as 'captive' interplanetary training missions, and the training is all about onboard operation, living and working in space for months at a time. LEO is much the best place to carry out that training, until we are ready to take our show on the road.

Rick said...

Laser boost technology could be advanced by laser space weapons, and space nuclear power plants if they go that route. (Though a few tons of chemfuel can provide a lot of zaps.)

But on the whole, I doubt that military developments add much to general space capability. There was an era around 1950 when military investment in intercontinental bombers and missiles had almost direct applicability to civil aviation and space lift. (And in the 1970 era military investment in ARPAnet gave us the Internet.)

In the modern era, however, military developments seem to have less crossover. Stealth capability is useless to a civil vehicle.

Military space competition in this century, I suspect, would do little to advance space travel and might well set it back.

Thucydides said...

Bureaucracy has a place, but it seems Pournelle's Iron Law takes over far too soon:

(In any bureaucracy, the people devoted to the benefit of the bureaucracy itself always get in control and those dedicated to the goals the bureaucracy is supposed to accomplish have less and less influence, and sometimes are eliminated entirely.)

Perhaps a more common criticism is bureaucracies tend to be or become rent seeking entities, to the detriment of the function they are supposed to be doing.

The Canadian forces is an infamous model; until recently there were more Captains than Corporals, and the forces has recently stood up a divisional headquarters, despite the entire size of the land element (Army) can scarcely be considered a division (and many soldiers are doing jobs like training, teaching, recruiting etc. which are outside the purview of the fighting units and thus not part of the Divisional structure anyway)

On the other hand, large corporations like WalMart seem able to operate with very "flat" hierarchies. I believe the ideal in organizational theory is five levels (although I don't believe any large corporate entity has reached that ideal).

I think what anti bureaucrats are getting at is there is a lot of resources and effort being expended in activities which do not add to the productivity (or profit) of an organization, and a great deal of purging and streamlining should be done.

A somewhat related idea is directive control and independent commands. Consider the HMS Surprise, which is a well organized ship with the crew divided into divisions and watches, under the various officers who report to "Lucky Jack" Aubrey. Captain Aubrey has his sailing orders, but unless the Admiral happens to be sailing in flag or hailing distance, he is free to interpret and carry out his orders as he sees fit. So long as there are positive outcomes, fleet headquarters isn't too concerned about how exactly "Lucky Jack" is getting things done.

Today's militaries have embraced "directive command" in principle, but technology has made it possible for high level commanders to monitor and intervene directly to the section (squad) level, which is a bit disconcerting, to say the least. Modern communications have also had the same effect on industry and commerce, in theory a bolt can be followed from the foundry to the seat of your car, and the sight of executives and sales people pulling out BlackBerries in a restaurant, airport lounge or car is so common it is hardly noticed anymore.

WRT small, nimble enterprises like the Skunk works or Scaled Composite Aircraft, I believe the idea of directive command is allowed to take root and operate there, no one is looking over "Lucky Jack's" shoulders, nor Clarence Kelly or Burt Rutan's shoulders either.

Fernando said...

Rick:

Yes, now that I see it, the Saturn Rocket had an enormous upper stage (I'm saying enormous in terms of money and research) to carry a service module to the Moon. The logistics and finances of a project like that would be too large, even if NASA got enough money and started working now. Still, would designs like that (a space station that would make periodic runs to the Moon) could work? It would be a reusable system, could be upgraded with new modules as needed and would carry way more astronauts and equipment that the Apollo or the Orion capsules, in a quite comfortable environment. The only problem I see, and is a big one, is how to move such a massive structure without spending ungodly amounts of money...

And about militaries in space: Those laser-stars that you guys talk about sound like very expensive systems to me. It's true that the military often spends that kind of money on far-fetched projects, but most of the time there's always a reason to expend billions of dollars in submarines, fighters, bombers, frigates etc. Unfortunately (well, for story proposes anyway) there is no compelling reason to waste so much money on a space military. I can think of three reason that would maybe work:

A) Orbital guard: Basically protecting Earth from asteroids threats both natural and artificial (miners fighting for independence, terrorists trying to cause damage). I'm pretty sure that the ships of the guard will have weapons, but be mostly unmanned (you don't need life support and all that to launch a nuke bus and "adjust" an asteroid trajectory). This space force seems logical to me, and probably will be enforced once we got a close call with a Near Earth Asteroid...

B) Star Wars program: Satellites equipped with various weapons that target nukes, other satellites and probably land targets. Wars with this system would be bloodless (unless we are talking of a satellite that can blow cities to kingdom come), unmanned and boring... Probably will happen in a few decades...

C) National prestige: China builds a laserstar that can blow the ISS to pieces, if they want. The USA build two of them to counter that "threat", Russia joins in the fray, and builds two laserstars. The USA build two more and deploys a space station to service them. China does the same, and India and Europe start their own projects. When you realize, the whole system is filled with laserstars, military space stations and missile buses, payed by the overinflated militaries of Earth, just to keep space under their control and maintain international prestige. This is the most unrealistic of scenarios, and also the most rocketpunk friendly; with military base soon comes civilian colonization at expenses of the military, and one could imagine most spaceships would be manned in case they have to take difficult decisions in space far away from the HQ. Combine this scenario with the other two up there and you got a quite busy and militarized space, ideal for any war thriller...

Robbie said...

Well I think of it like this. Say the US builds a laserstar to blast away dangerously close asteroids, the Chinese could say it's also a weapon for zapping earth side military targets and so they build their own laserstar to protect their assets. The Russians then follow suit and build their own laserstar, in response the US builds more and before you know it you have weaponized space.

Robbie said...

This is very similar to a game that just came out called Vanquish. The US builds an orbital solar power station, and the Russians hijack it and use its power to blow up LA, then threaten to destroy NY if the US doesn't surrender.

Thucydides said...

Second comment WRT sled "zero stages".

Unless the sled is driven by something like a linear induction motor and suspended on a maglev cushion, I doubt there will be any real gains from using a sled. This is just a holdover from the Sanger "Silverbird" rocket bomber, conceived at a time when rocket motors were not powerful enough to boost the ship into orbit.

An electric sled has the potential to store energy during off peak times in capacitors or flywheels and release it in a fast, controlled surge. Then again, that sort of power could also be used to energize a bank of lasers to launch a "lightcraft" or similar laser thermal drive, or lob it into orbit using a "slingatron" or similar device. Properly scaled, you might as well use the sled to provide the entire boost energy, with a small motor to circularize the orbit once beyond the atmosphere (ensure a very long evacuated tube is provided for launch).

Anonymous said...

What can I do, as an individual, to help?

Rick said...

For a large airbreather a sled is viable, to get it up to tolerable ram/scramjet operating speed. At low speeds they produce no thrust to speak of. (Small airbreathers would be launched from aircraft.)

But I would just use a rocket sled. The power requirement is enormous, a gigawatt or more. Building an electric sled is developing a whole new technology when a rocket sled will do the job.

Robbie said...

Yeah, I'm starting to realize it's not a very good idea for space launch. I just read you would have to drill a tunnel through a 12,000 foot mountain to make it work. I don't think that's gonna happen, lol.

Robbie said...

Just best to stick with nuclear thermal rockets, like the Liberty Ship. But it looks like that's not gonna happen any time soon, either...

Fernando said...

On the risk of opening a can of worms, what about space elevators, birfost bridges, Lofstrom loops? I may be wrong, but I think that there was never a post on these exotic means to get into orbit...
Sure, they are expensive, and pretty much on the development phase... but someone, sometime in the future would build one of these systems (I'm betting it would be first an space elevator). Would they really have a great change on the prices of getting something to orbit? I mean, right now you literally have to pay your weight in gold to get in space... maybe with a space elevator you just have to pay your weight in iron or oil...

Who do you think would be the first on build these launchers, if at all?

Elukka said...

Fernando, radiation would be an issue if you were to take the ISS outside LEO. It's built for the radiation conditions there, i.e. it uses the Earth's magnetic field for shielding.

Apollo, to my knowledge, didn't have any significant radiation shielding either; they just took the hit, but I'm not sure we'd want to make that into a regular thing.

Robbie said...

That's what would scare me the most of all; getting fried by a solar storm, and there would be no gaining super powers like the Fantastic Four. lol

Citizen Joe said...

The Rocket Sled design I've seen involve a 'cannon' that floats out in the ocean. One end goes very deep into the water. The advantage is that you can place it at the equator pretty easy (for best launch), plus the whole thing can be moved about for security or tactical reasons. Another benefit is the use of the ocean water as a heat sink for what is likely to be phenomenal waste heat.

I know we discussed space elevators earlier, not sure how far back though. We could do a lunar elevator to a LaGrangian point with current materials, but there isn't enough justification to do so yet. An Earth based elevator would need some sort of anchor point at GEO with a counterweight further out to support the mass of the actual elevator. To minimize wear on the cables, and provide a means to service the cables, I would build a stationary guide cable and then have a lift cable attached to a buss on one end and a counterweight the other. Lift would be generated by letting the counterweight spool out thus increasing the centrifugal force and lifting the package. Return cable would likewise spool out from the Earth based anchor and would be inspected for problems as it goes. By controlling the speed of the spools and the altitude of the counterweight (spool), you can control the rate of ascent of your elevator without powering the elevator or gripping the cable (which causes wear and tear). Since the lifting power is derived from the counterweight, you don't need massively powerful winches (although they'd still be very powerful, just not as big as they'd be if they had to lift the whole rig directly).

Rick said...

'Alternative' launch technologies:

I've written previously about elevators. Short form, an elevator is, essentially, a railroad to outer space, and a truly colossal civil engineering project. I don't see putting up an elevator until/unless you have railroad level traffic volume.

Also bear in mind that if we can make a cable out of carbon nanofibers we can also use them in airframes, and the lighter structure could make reusable orbiters more viable.

I don't know enough about Bifrost bridges, loops, and such to comment on them in any detail, but they all seem to require a) development of a whole new tech, and b) massive civil engineering.

Tony said...

Rick:

"I don't know how it is in Russia. It could be much the same thing, or it could be that the Russian military is basically owned by tankers, who want nothing from space but the positions of the other side's tanks."

Certainly after they lost the Moon Race they focused their manned space program on strategic reconaissance. (They didn't even care about enemy tanks; they cared about US missiles and bombers.) After they had good enough robotic spacecraft, they seem to have concentrated on all of the same things we did with robotic staellites.

The service politics dimension didn't really exist, because the Russians are somewhat more rational about such things. Service involvement in manned spaceflight was exclusively an air force thing, with an early institution (in the 80s IIRC) of an national level space forces command. Also, the Soviets didn't try to hang a lampshade on the fact that ballistic missiles are artillery, and siege artillery at that. So they formed a strategic rocket force separate from the air force and the army, that could follow the most rational path.

Raymond said...

Tony:

WRT drive optimization, we'll probably have to wait until we start scaling up VASIMR before we'll get an idea what kinds of optimizations are feasible. I think powerplants are a better place to start.

Also, when SDI was in its planning stages, was it planned to go to the Air Force, or were they going to peel off Space Command into its own force?

Tony said...

Raymond:

"WRT drive optimization, we'll probably have to wait until we start scaling up VASIMR before we'll get an idea what kinds of optimizations are feasible. I think powerplants are a better place to start."

As a good object-oriented type of guy, I'm highly agnostic about the details. I'm only trying to suggest that taking the problem piecewise should offer opportunities for optimization.

"Also, when SDI was in its planning stages, was it planned to go to the Air Force, or were they going to peel off Space Command into its own force?"

I don't think they thought it through that far. The actual SDI office was a USAF activity. I'm pretty sure that, at the highest levels within that organization, they understood that the whole thing was a put-up job designed to suck the Soviets into a phony, but resource depleting, arms race.

In more general terms, I'm not 100% (or even 75%) convinced that a separate space command for Earth-oriented space application is necessary or even desirable. The Air Force owns space due to a set of non-imperative historical accidents, but that's all. I don't think space should be a major command within any one service, or it's own service altogether. I think it should be handled as a joint global command, because it has serious stakeholders in every service, and it has global reach and responsibilities.

Thucydides said...

The greatest problem with civil engineering solutions to space, like elevators, loops, bridges etc is the size and scale of the devices compared to the size of payload you can send to orbit using them.

A Loftstrom loop covers about 2000 miles of the Pacific Ocean, uses gigawatts of energy but can only fire a 5 ton payload into orbit. Now it can fire several each hour (providing a margin for dumping waste heat from the loop), but this means you have to build your spaceship out of five ton modules, of have some sort of interface to accept lots of five ton modules bringing remass and other supplies.

Elevators can scale a bit better, a billion ton elevator can in theory lift a 700 ton spaceship from ground to GEO, but that is a bit of a stratch

Carla said...

"Which might be a feature, not a bug: a Solar System touched more by our aspirations than our failings."

That's rather poetic; an attractive image.

Jedidia said...

Another benefit is the use of the ocean water as a heat sink for what is likely to be phenomenal waste heat.

I know that the netherlands and venice won't be very fond of such a plan, and a lot of coastal and island regions with them. And I could completely understand them. Not to mention that dumping "phenomenal waste heat" into the oceans can prett easily disrupt the great currents, which are pretty important to our ecosystem. So I wouldn't risk it either.

And then there's still the problem that you're comming out of that tube at Mach two at main sea level. I don't know of any airframe that could withstand such stresses. No, rocket sleds still seem a pretty bad idea to me.

Rick said...

Carla - That would be good for humanity and the Solar System, but bad for writers; the human failings provide most of the story material.

Citizen Joe said...

The Loftstrom Loop has a couple of nice features. First of all, your payload doesn't reach supersonic until after you've reached 80 km altitude. At that point the heat build is probably manageable. Second, it has only a 3G acceleration which seems to make it quite useful for lifting people, which is well under the 5 ton limit. That means that heavy lift can be done unmanned with your higher acceleration lift mechanisms, like 20G mass driver cannons, with ablative thermal sabot.

We're still looking at some sort of assembly in space, whether it is getting people to their station or assembling components.

Five ton empty modules seems feasible and comparable to what is being used for the I.S.S. Full modules are closer to 10 tons though. That would seem to imply that loop cargo modules would be about 2 tons dry. That is about the mass of a 20' Isocontainer, which makes for easy shipping to the launch loop.

Robbie said...

The gas core nuclear reactor Liberty Ship rocket sounds so awesome. Sucker can lift 1,000 tons of cargo to LEO, TONS not pounds, and can fly back and perform a powered landing! Now THAT would be badass.

Tony said...

Robbie:

"The gas core nuclear reactor Liberty Ship rocket sounds so awesome. Sucker can lift 1,000 tons of cargo to LEO, TONS not pounds, and can fly back and perform a powered landing! Now THAT would be badass."

That will never, ever happen. Launching nuclear materials for spacecraft power plants on a one way trip into orbit is one thing. Flying nukes around in the sky on a routine basis? That's just crazy.

Robbie said...

Then we're screwed. Spaceflight will forever be for the ultra-rich only. With it taking months or years to go any where.

Jedidia said...

The gas core nuclear reactor Liberty Ship rocket sounds so awesome. Sucker can lift 1,000 tons of cargo to LEO, TONS not pounds, and can fly back and perform a powered landing! Now THAT would be badass.

1000 tons SSTO? Sounds *very* utopian even for a gas core. You got any link to the concept handy? maybe it's been posted already and I missed it, in that case apologies).

Tony said...

Robbie:

"Then we're screwed. Spaceflight will forever be for the ultra-rich only. With it taking months or years to go any where."

Spaceflight will be what it will be. It's not for you, it's not for me, it's not for anybody in particular. It's for the good of the species, to the degree that it actually is for the good of the species. Putting any kind of idelological baggage or personal agenda on it isn't helping.

Rick said...

For a long time to come, the best and practically only way to get into space will be to have a strong, focused desire to go there from childhood, and be a prime physical and mental specimen of the upright ape. Space agencies can and will be meritocratic when it comes to selecting ten-person crews for $5 billion spacecraft.

A few people will get there by being either absurdly rich or extremely influential, but they will be a small minority.

Citizen Joe said...

They will also be called "Payload"

Anonymous said...

Then we're screwed.

No, man. Tethers Unlimited solar-powered rotovators/skyhook/slingshots combined with JP Aerospace high-altitude balloons means cheap space for everyone in the very near future!!!

They could sling Bigelow modules into space all day long!!! For FREE!!!

Rick said...

Gives a whole new meaning to pie in the sky.

But I encourage people signed in as anonymous to sign their names in their posts.

Scott said...

And here's the links for the 'Liberty Ship':

http://www.projectrho.com/rocket/surfaceorbit.php#GCNR_Liberty_Ship

and

http://nextbigfuture.com/2007/07/gaseous-core-nuclear-design-liberty.html

Still has a problem with blasting nuclear material out through the nozzles, though.

Citizen Joe said...

One of the problems I see is the same for multiplayer games... Griefers. In the Loftstrom Loop example, there's 2000 miles of loop that could be targeted by some bonehead with a SAM. How do you protect that much structure?

Raymond said...

Scott beat me to the Liberty Ship nonsense link.

Summary: As tall as a Saturn V, but twice the diameter. Powered by closed-cycle gas-core nuclear-thermal engines which run on a speculatronium/hypotheticum alloy. Uses regenerative cooling of quartz and a core temperature so hot the blackbody radiation is mostly ultraviolet. Reenters and lands under power while carrying large amounts of gaseous radioactive death.

Not. Bloody. Likely.

Robbie said...

Any one ever hear of the Skylon? It's an SSTO space plane being built by a british company called Reaction Enngines Limited, they plan to have it flying by 2020. Check out the company website: http://www.reactionengines.co.uk/skylon.html

Geoffrey S H said...

"Not. Bloody. Likely."

You mean politically or physically?

"Scott beat me to the Liberty Ship nonsense link."

Its got to the point whre I see any project NASA didn't do as scientifically implausible. not a "missed oportunity".

That includes the Orion Projects and Saturn V trips to Saturn etc. Space Elevators, Liberty Rockets, and even the new "Ares" carriers for theOOrion Cpasule (its taken decades to get off the ground for crying out loud!).
The number of projects that I have seen dismissed here is approaching double figures.

I suppose I should instantly dismiss VASIMR as vapourware? Given that it projects flights to mars that take less than 5 years?

They probably cut NASA funding because we didn't have the technology to do anything else, rather than lack of interest after the moon landings.

Heck, the Moon landings were probably half down to luck.

Basically, if a concept is easier than what we can do now, exiting, aesthetically pleasing, interesting, and promises a larger payload, then it is impossible. Period.

Robbie said...

It got me very excited, because it looks like a lot like the space plane from 2001: A Space Odyssey.

Geoffrey S H said...

@ Robbie.

We established SKYLON to be impossible and vapourware. It will never work. The "heat-exchanger" on the site is probably a fraudulent model, rather than a working mechanism.

Its a nice ideas, but impossible.

Robbie said...

What about Virgin Galactic, is their thing impossible too?

Geoffrey S H said...

I'll take the plunge... and say yes.

If they have SOMEHOW managed low-orbit with such a small craft (whch I highly doubt- its just a nice idea that brings in money), then they will NEVER reach anything higher with the small two-stage craft they have.
I think the whole idea will eventually just dry up and be forgotten.

Its just a fad, that millionaries will quickly tire of.

Robbie said...

So that explains why SpaceX went with the staged rocket, instead of wasting time on some thing stupid like an SSTO space plane. Because staged rockets are the only thing that works.

Geoffrey S H said...

Once again, I would hedge it won't work- too small. Sorry.

I've had this for some weeks, going from solution to solution and finding nothing works. Best to assume nothing will. ;)

Raymond said...

Geoffrey:

"You mean politically or physically? "

Physically, I'm doubtful of that specific variety of gas-core nuclear reactor. Too much heat, no electromag containment, too many failure modes and no graceful degradation. The numbers proposed by Anthony Tate (the guy who wrote the original essay) are, well, speculative at best, given that we have no baseline for comparison (whereas with solid-core nuke thermal, we've got extensive and well-documented NERVA research to establish feasible parameters).

Politically it's as close to impossible as you get.

Skylon, well, even the main guy behind it, Alan Bond, admits it's currently in the "establishing feasibility" stage (technology readiness level 2-3). The British government is only funding a bit of continuing research on the engines for now. We'll see, but I wouldn't put it on the official roadmap.

For the rest, it's not that they're all vaporware or impossible or implausible - it's that they're unproven or mind-bogglingly expensive or both. Take the launch loop: a two thousand kilometer rollercoaster floating in the air, which we could build with current materials if we decided cheap space access was worth the ten trillion dollars we'd throw at the project. I like the idea, myself, but that's too much money upfront for even a multinational consortium to really consider anytime soon.

Robbie:

SpaceX's purpose is to drive down launch costs - going with what works but making it cheaper is exactly their strategy, and a two-stage rocket is the only thing we've found that works for sure.

SSTO is problematic from an engineering perspective because of the staggering number of tradeoffs and compromises required, even if/when we get the materials to reliably bridge the various contradictory environments launch and reentry represent (without the heatshield tiles breaking when breathed upon, that is).

Virgin Galactic's craft are suborbital-only, thus avoiding the stresses of reentry from orbital speeds and the hideous mass ratios involved with getting to orbit in the first place.

Raymond said...

Addendum:

VASIMR isn't among the vaporware proposals because Ad Astra Rocket Company has actually done fairly well at reasonable timeframes and gradual development. They've done successful ground tests, and are looking at a full space test aboard the ISS in the next couple years. So far, so good, and the tech looks to scale well to boot.

What isn't so definite is the powerplant attached to it. Solar panels in the class of Rick's butterflies are still not at production status. Space nuclear reactors are on many drawing boards, but nobody's really started building them yet. If VASIMR's space tests are successful, and some improvements can be made when it's scaled up to the multimegawatt range, then the reactors may follow.

Robbie said...

So basically space travel will never be any thing like commercial air travel.

Reality is a bitch. lol

Geoffrey S H said...

Don't get me wrong with what I am about to say- I respect you and what you have said given your work in the engineering field. But: I am simply going to ignore everything siad there and asssume for now that VASIMR and any prospective technology is impossible, scientifically and politically. VASIMR (and NERVA!) is too exiting, too interesting, too conveniant.

Its not so much that I don't believe you, heck, your the one with the qualifications here.

Its just that I am becoming so jaded with new concepts of space travel, seeing someone with scientific qualifications state something ground-reaking will work, that whenever something like this comes up, then I find someone telling me "nope, won't work, sorry". Best to Assume it won't before someone tells me. In the world of science, pessimism is king.

Nevertheless, thank-you for stating what you did. It was helpful and I will note it down fo future use/ reference.

Raymond said...

Me? I'm not an engineer. I'm also not normally this pessimistic. But there's a difference between "we've got a working prototype or three and we've signed the contract with NASA for the next stage of testing" (VASIMR) and "this can be built at huge expense and would likely work, but again, it's really expensive" (Lofstrom loop).

There's also "if we get this super-material/engineering breakthrough/plausible-but-not-confirmed configuration of matter, then here's something that would work" (space elevator/D-He3 fusion reactor/metallic hydrogen rocket fuel). If/then. If, great. If not, oh well.

Things which would drastically change the cost (and possibly nature) of space access, which if we actually find and develop, will be awesome, in no particular order:

- carbon nanotube weave aka Super Nano Carbon stuff (better chances for SSTO vehicles, would allow space elevators)
- metallic hydrogen (best rocket fuel you can think of, if not too expensive to produce would drastically improve payload fractions)
- room temperature superconductors (would increase chances of economical fusion reactors, amazing batteries)
- usable D-He3 fusion (power galore, Really Fast interplanetary travel, reason to go to Jupiter/Saturn/Uranus)

If, sweet. Else, carry on with rockets.

Robbie said...

There was a concept I read about a couple years ago where they mass manufacture expendable rocket boosters. Damned if I can't remember what it was called.

Robbie said...

Did a google search and it came right up. It's called Big Dumb Booster, basically it would be cheaper to mass produce simply designed boosters, instead of designing a complex high performance rocket that you fire only once and then discard.

Robbie said...

It would be like how Henry Ford made automobiles affordable for every one by mass producing them on an assembly line. That's the same idea behind the Big Dumb Booster.

Tony said...

Re: Robbie

"Big Dumb Booster" (BDB) is just an unmanned staged heavy lifter. The terminology came from comparison with the Shuttle, which, in the same lexicon, would probably be called a "Big Smart Launch System". (Not that it ever actually was.) The distinction between "Dumb" and "Smart" is between unmanned or manned. The distinction between "Booster" and "Launch System" is between a wholly expendable launch vehicle and a semi-expendable one.

IOW, it was just a perjorative coming out of the Shuttle community, aimed at expendable launchers. But, in the aftermath of the Challenger, the Air Force types who were never that in love with Shuttle to begin with adopted BDB as a sort of rallying cry, as if to say, "Our booster may be big and dumb, but they work, and they don't kill people."

Having said all of that, of course if the demand ever goes up high enough, the cost per kilogram of payload launched by expendables will go down. But the demand has to go up first.

Jim Baerg said...

Re: Alternative Launch Technologies.

For something fairly near term like the next few decades I like the hypersonic skyhook or the hypersonic rotavator combined with a single stage rocket that can get a few hundred km up with a horizontal speed of 5 or 6 km/s.

The skyhook can be done with currently available materials unlike the surface to geosynch elevator & the reduction in delta-V for the rocket makes it easy to do with chemical fuels & currently available materials. Most importantly the skyhook isn't as enourmously bigger than the payload it helps launch as a launch loop or elevator.

Re: Gas Core Nuclear 'Liberty Ship'
If it works at all (BIG IF) it shouldn't be very dangerous to bystanders since it looks like the design would need to carry barely more fissionables than is required to power the mission, so there wouldn't be all that much radioactivity scattered about in the event of a crash. Also the design would keep the radioactives inside in normal operation. I would be inclined to leave the fission products in orbit for storage in high earth orbit so on return to ground there isn't radioactivity to be scattered in a crash.

Rick said...

In this series of posts I am casting a rather jaundiced eye at a lot of proposed space techs, because space advocates over the years have been so notoriously guilty of hype.

This includes potentially viable techs as well as vaporware. No one, after all, was a more notorious hype-meister than Werner von Braun, though his technical ideas were not unsound.

Robbie said...

Well I'm a fan of the nuclear reactor rocket, because like the guy at Atomic Rocket says: No self respecting rocketeer wants to ride a disintegrating totem pole into space.

Jedidia said...

considering the technologies discussed here:

The liberty ship suffers a similiar problem as the orion, IMHO: even a successfull launch is a rough equivalent of detonating a nuke. I don't even want to know what would happen if such a liberty ship would go bad... It seems a nice concept for use in science fiction scenarios, though, because IF they could get the closed cycle gas core working we could launch it more or less radiation free (apart from UVs... get the sunblockers out!).

I'm sceptical about the Skylon. its payload mass would be pretty limited, but I'll see how the project progresses. I seriously doubt I'll see it flying one day, but I'll keep a glimmer of hope that they will surprise me.

VASIMR: certainly not anymore vapourware than the NERVA, but maybe no less either. We have working prototypes of both, they're feasible concepts. The major trouble for the VASIMR is getting a lightweight nuclear reactor to go with it, so it's still questionable if the thing is really practical. If we want to do manned interplanetary travel, I'm convinced it's the only sensible way to go, short of fusion drives, which might or might not ever come to be.

BDB: cheap boosters, for sure, but the launch facility costs are out of proportion, especially considering that you'd barely use them.

Tony said...

Robbie:

"Well I'm a fan of the nuclear reactor rocket, because like the guy at Atomic Rocket says: No self respecting rocketeer wants to ride a disintegrating totem pole into space."

WIth all due respect ot Mr. Chung, no self-respecting rocketeer wants to ignore the constraints of physical reality. If those constraints include riding a disintegrating totem pole into space, that's just the way the cookie crumbles.

Rick said...

I am sure that Winch Chung would agree. Atomic Rockets, like this blog, walks the delicate and complex line between real space travel and space opera.

Sabersonic said...

Might as well put in my two-cents on the subject since as of late since everyone is talking about surface-to-orbit technology and make it economically feasible enough to have the plausible mid-future envisioned at the very least. Which makes sense, if you can't get at least the parts for your space station, laser stars, satellite weapons, and interplanetary rocket drives without breaking the bank first then we're screwed in the long run.

Libery Ship:
From what I understand the greatest argument in the design, beyond the claimed payload, is the nuclear rocket idea itself. From what I understand of the Atomic Rocket Entry, the potentially lethal (to both living and environment) nuclear radiation is mostly internal and that it only heats the propellant to exhaust velocities through a kind of thermal exchange not unlike a radiator rather then mixing it with an oxidant as with conventional chemical rockets. From what I'm getting in these comments is that there is some radiation from it's use in the Ultraviolet range at the very least. Noticeable but I have the feeling that its easier and potentially cheaper to shield against then what is thrown out the back of an open-cycle gas nuclear rocket design.

As for the current thinking that reusable SSTO vehicles not being the best of ideas due to technological, engineering, and economical challenges, well from what I see it the Liberty-class HLV would have to be reusable or at least the important systems should be. Pretty sure that it's never a good idea to have an expendable nuclear reactor even if it is technologically possible, which I highly doubt.

Though while we're on the subject, is there a proposed nuclear fusion version of the Nuclear Lightbulb design?

Big Dumb Boosters:
From what I understand of the wikipedia article, the US approach of the concept is not the most ideal path to follow. The idea behind the BDB is that it's suppose to be economically viable enough for mass production of expendable heavy-launch rockets. Having parts with tolerances so tight that it might as well be a custom job for each unit to create is not exactly what I call "mass production". Granted, this may also logically lead to the thought that having a more 'sturdy' rocket might cut into the payload to such a degree that it questions its general use. Perhaps a middle ground could be achieved with the two extremes?

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Tony said...

Rick:

I've always viewed Mr. Chung's work as: "Here's the reality; if you want to ignore reality, here is how you do it in the least implausible manner..." So, I went back and checked. The sentiment Robbie misquoted (Chung said "Space Cadet", not "rocketeer") was explicitly part of a denial of reality, for purposes of discussion only. It wasn't a statement of principles.

Sabersonic said...

Continued from previous reply:

Space Elevator:
As Rick stated, the concept of the space elevator is effectively a railroad into space and that its construction could only be facilitated if there was a high enough traffic and/or high enough demand for such a construction effort. If I remember the argument correctly, if such high surface-to-orbit traffic is high enough then that would also mean that there was also an STO vehicle that is the backbone of such traffic and is theoretically more economical to provide such high volume of commerce then the construction of said space elevator.

This leads to the question as to what the space elevator could do that regular STO vehicles could not perform other then potentially smaller chance of a fatal accident in comparison to what is basically a controlled explosion. There is of course the idea that a nation-state or supranational government could monopolize access into LEO through a kind of toll, but then again the argument could be said of launch pads and purchase of rocket STO vehicles if not rental of reusable SSTO craft.

Perhaps it needs to combine with another space-based system so it doesn't become a "one trick pony" as it were. Perhaps something that would make it illogical for an STO to perform as well as This little monologue suggests. Perhaps not the ideal solution, but it does spark debate.

Though, to be honest, the concept and base technology for rotovators and skyhooks sounds more ideal then a space elevator since what is needed is a hypersonic aircraft to lift payload to the required altitude. If I recall correctly, we're much closer to the creation of a hypersonic aircraft then we are at the construction of a space elevator.

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Tony said...

Sabersonic:

"From what I understand of the wikipedia article, the US approach of the concept is not the most ideal path to follow..."

It depends on which "US approach" you're talking about.

Between the Atlas and Titan programs, depending on launch vehicle configuration, we've had Little Dumb Boosters, Medium Dumb Boosters, and Almost Big Dumb Boosters. The core stages were originally ballistic missiles designed to be series produced and as inexpensive as possible. In the Atlas program, each missile's silo and support equipment cost more than the missile, to say nothing of ongoing operational costs of the missiles in service.

When speaking of purpose-built launch vehicles, of course they are specialty items, because the
demand just isn't there for anything else. It took over thirty years to use up the Atlas and Titan inventories. Even the Russians, who are supposedly doing it the "right eay", build rockets to meet their launch manifests. They're doing it as efficiently as possible, but they still have to do it that way.

Aside from all of that, with the payloads being expensive as they are, you have to build and operate for high reliability. That means that no matter how streamlined you make the manufacturing process, you still have to handle everything very carefully, keep a paper trail on every part, inspect and requalify anything that gets dropped/bumped, etc.

Elukka said...

I think the point of the Liberty Ship is more to show that Nuclear is Really Powerful than to propose that the particular craft be built.
The site of the original article has been down for a while; now it's up but seems unfinished and the article still isn't there. So here's the guy's (pretty good) points on safety, courtesy of the Google cache.


Here (pdf link, scroll to page 48) is a slightly more conservative NTR design that uses conventional solid cores. Though I wonder if it wouldn't be better to make it two stage to make use of denser chemical fuel and the excellent thrust-to-weight ratios of chemical rockets in the first stage, and save the NTRs for a second.

Tony said...

Elukka:

"So here's the guy's (pretty good) points on safety, courtesy of the Google cache."

That's ome of the most ethically obtuse sophistry I've ever read.

There's a reason they stopped testing nuclear devices in the atmosphere. It's the same reason that Freeman Dyson eventually turned against Orion type nuclear pulse propulsion -- increased terminal cancer risk. Now, there's no way to tell who's going to die due to a nuclear test detonation or a nuclear spaceship launch, but there is a statistical certainty that a number of people will. For those deaths, the people who detonate bombs or fly nuke ships are just as guilty as if they'd held a gun to the victims' heads and pulled the trigger.

Not that they could be prosecuted following the normal rules of law, but that doesn't remove their moral and ethical responsibility. Say that you'll only risk the release of a little bit of radiation, in a "safe" place, is a moral and ethical punt of the most outlandish proportion. Anybody that practices that kind of rhetorical chicanery isn't worthy of attention, much less trust.

Luke said...

Tony,

There is a lot of uncertainty about the medical effects of radiation at low doses. The assumption that has generally been used is the "linear no-threshold model", which basically means that if a dose of X makes a number Y people die of cancer in 30 years, then a dose of X/1000 will make a number Y/1000 people die of cancer in 30 years. It is something of a safe model, since it is expected that it will not under-predict the number of fatalities. However, for these sorts of low probability events (a person contracting cancer from a low dose), there is no good way to reliably test the model. A competing hypothesis would be that below some threshold, the body is good at repairing radiation damage and exposures within this threshold do not raise the probability of death or other bad things. Currently, there is no evidence either way (nor, for that matter, evidence that low doses are not actually worse than the linear no-threshold model would predict). There are biological arguments that there should be a threshold effect - but then advocates of the LNT model have arguments that there should not be a threshold effect, too. As it is, we really don't know if the globally distributed radioactivity of nuclear test blasts killed anyone at all (note the caveat of "globally distributed" - some people definitely were killed by local fallout, I am not questioning that). If there is a threshold dose, then the launch of a nuclear-powered rocket with suitable safety measures and which emits a low enough quantity of radionuclides would not be expected to kill anyone, barring unfortunate accidents.

Tony said...

Re: Luke

I used to accept the threshold model myself. Then it occurred to me that the arguments in its favor if it was a rationalization are indistinguishable from the arguments in its favor if it were valid. When confronted with that kind of situation, I always decidei n the favor of rationalization. YMMV.

Geoffrey S H said...

Being a historian, I thought I'd put in some analylitical arguments in here... they're not good, but can be expanded on.

Polynesian setting: afew trips into the athmosphere, and then a cessation. Thousands of years before we return to the moon.

Viking: The moon is our "Greenland" and Mars our "New World". One trip or so, and then around a millenia before we return.

The dawn of the first water-craft/ or expansuion from Africa at the dawn of humanity: Millions of years before we venture beyond Earth's high orbit, excluding robotic probes.

Right now, I'm leaning towards the last, out of cynicism, if we ever get out of here.

The way I see it, if you want a rocketpunk future- take the second. After the Vikings came and went, much developement on the copasts of europe occured. This eventually created ships that could cross anywhere, but still stuck to the coast. Ultimately it was realised that they could be used for better things, and where. However, I don;t think this will happen due to all the arguments above.

However, if you want this setting, you will thus have to MASSIVELY develope LEO and HEO- thousands of orbitals, stations and asteroid (towed) mines before you get anywhere.

And asteroid (towed) mines are currently completely impossible.

Thucydides said...

The "classical" Big Dumb Booster is a pressure fed rocket using a very simple engine scaled up from the TRW design used by the LEM. Since the LEM engine needed to be 100% reliable or the astronauts would never leave the lunar surface, the engine had as few moving parts as possible.

A scaled up model was made to test the theory, and was built to "shipyard" standards (TRW supplied the injector, which was the only high tech part). It proved to be successful, and produced something on the order of 55,000 lbs of thrust. TRW (among others) continued to study the concept including building the entire rocket out of steel to reduce cost, but the concept died when the Space Shuttle was selected as the next space system, and aerospace companies followed the customer.

The BDB concept is still around in various forms (the Aquarius sea launch concept, for example), but state of the art has also progressed, and reliable high power engines using turbopumps probably outperform any souped up pressure fed engine.

There may be some really far out launch system using the earth's magnetic field or equally unlikely physical effect, but these are magitech for now. The only viable low cost, high power and reliable system to get to orbit seems to be Liek Myrabo's "Lightcraft", which uses simple, inexpensive spacecraft and leaves the expensive parts on the ground.

WRT Skylon, this is an update of the LACE (Liquid Air Cycle Engine) systems proposed back in the rocketpunk era. Apparently the system was made to work back then with some low powered "bench" engines, but there were few advantages over rockets and lots of disadvantages (a heavy, complex and expensive system is on board the ship and must be carried throughout the flight). from what I can see from the Skylon site, they have simplified the LACE system and use up to date materials, but they haven't demonstrated a working system as yet.

Jim Baerg said...

Tony: "That's ome of the most ethically obtuse sophistry I've ever read."

I'm inclined to say the same thing about your comments.

So there is some chance that a crash of the Liberty Ship nuclear rocket would release some radioactivity that might kill somebody. If that makes it unethical to use such a rocket then it is also unethical for me to drive a car since it might collide with someone or the exhaust could cause cancer in people who breath it in.

Do you think that a death due to something to do with nuclear power is somehow worse than a death due to other causes?

Whether the 'nuclear lightbulb' rocket can be made to work is another matter, & if it is workable it hazards would need to be compared to the non-nuclear hazards that are accepted by humanity, not just declared they must be zero because it is a nuclear device.

Raymond said...

We should remember that the risk from a closed-cycle nuclear engine is from explosion or breakup during reentry, not necessarily general operation. The whole concept of a closed cycle is that the reactor core is separated from the propellant it heats by a solid material. In the case of the Liberty Ship's engines, it's quartz, which would be transparent to the UV emissions from the core, allowing heat transfer via blackbody radiation, instead of conduction. (Supposedly, anyway - I don't know how we're supposed to contain a reaction at 16,000 K with a material which melts at under 2,000 K, but that's "just an engineering detail".)

If we tentatively accept the concept as plausible, we still have to realize that in case of explosion or disintegration upon reentry the nuclear fuel would be in gaseous form, which presents all sorts of hazards for dispersion and contamination over a wide area.

Solid-core NTR concepts, however, have a much more limited risk from the fuel elements in such a scenario, as according to the NERVA crash tests, the core would most likely land relatively intact. The graphite-based fuel elements could withstand reentry temperatures, and would perhaps shatter on impact, but not vaporize and disperse over hundreds or thousands of square km.

One of the chief concerns in the NERVA program, though, was how to reduce corrosion of the core (and accompanying release of radioactive material) by the propellant. Their conclusion was either to develop better fuel materials (high-temperature uranium oxides, which would react far less with hydrogen) or place a layer of silicon carbide (which is already used in TRISO fuel elements for high-temperature reactors). This would reduce the problem, perhaps by several orders of magnitude, but it's unlikely we can completely eliminate it without overly compromising performance (and thus eliminating NTR's possible advantages over chemfuel).

Whether we can develop a core able to be used in the upper atmosphere as a second stage, or if we have to limit its use to LEO or above, it's doubtful that we could safely use solid-core NTR as a first-stage engine.

Elukka said...

Well, NERVA resulted in a functional third stage engine.

Anonymous said...

As I've read these posts, I can't help but be dismayed by how many of the commentators' opinions are so negative; your level of pessimism is staggering and, on the whole, unhelpful. I know that you will defend yourselves with 'only being realistic'...realisim is a balanced look at both the pros and cons of any system or technology, not a knee-jerk comdemnation of anything 'not-yet-proven'...in 1890 people with your attitude would have condemed automobles, air travel, manned rocket travel, and the telecommunications industry, among many others. Just because you don't agree with something because of a philosophical or phobia-driven motive rather than because you can demostrate a physical, engineering, or technical fatal flaw, makes you sound like a chronic nay-sayer rather that an informed critic. Sorry that this sounds so much like a rant, but the tone of this thread is rapidly going downhill.
(returing to the subject of the original post)
So, a challange to everybody: what can we do to break the too-high-per-kilo launch price vs. the launch-price-won't-come-down-till-the launch-tempo-increases conundrum? Can we come up with a new orbital use that needs a much higher launch tempo? How about some realistic innovation that reduces the cost of the launch vehicle? Perhaps a new model of business that reduces the payload cost or insurance risk? So, do you think we can be a little more positive, yet still be within the bounds of plausibility?

Ferrell

Robbie said...

Well said, Ferrell! The extreme pessimism in these comments were almost making me depressed too.

Thucydides said...

Pessimism or realism?

I am enthusiastic about lots of different things, but in the end, the laws of physics and economics determine what will exist in the "real world".

Like Rick said, there is a certain tension between the plausible midfuture(tm) and Romance (especially space opera). If a technology is too expensive, or does not have a clear advantage over existing technologies, then the existing technologies will win out every time. Not only are they cheaper and well known, but also have armies of technicians, infrastructure etc. behind them. Gasoline powered IC engined cars will be with us for a long time to come for those vary reasons. Even if I created a magictech battery tomorrow, you would have no charging station for your electric car. Government subsidies can change the situation by favouring some activities or products over others, but the risks are huge (banning light bulbs in favour of CFL's placed a mercury hazard in everyone's home and workplace and also seriously delayed the development of far more efficient LED area lights. we now also have a giant disposal problem for old CFL light bulbs). I imagine that without tax credits or other subsidies, the Toyota Prius and similar hybrids would be exotic rarities parked beside Ferrari's rather than ho hum commuter vehicles (and if subsidies were to end, so would these cars. Something to think about in this age of trillion dollar deficits).

So while the Rocketpunk universe has tramp freighters in space, my universe has 20' ISO shipping containers in minimum trajectory orbits. Space patrols and space navies are great fun to speculate about, until it turns out the Space navy is robot KKV busses and laserstar constellations with maybe a few command nodes. Space stations seem to be under attack here as well for astrodynamic reasons (add complicated extra orbital burns) as well as the usual financial and engineering objections.

Maybe we need to have some sort of two screen view: Rocketpunk/Realpunk

Realpunk can be just as exciting; Mars Direct vs "Das Marsprojekt", VASMIR drive vs "Torchships", just in a different sort of way.

Thucydides said...

On a different topic:

Nuclear Light Bulbs emitting blackbody radiation in the UV range is not the same as the radiation happening in the reactor chamber. Should the quartz capsule be breached, highly radioactive gasses will be expelled at high speeds (along with radioactive engine parts), which will disturb a lot of people.

I always thought the key weakness with a nuclear light bulb was the energy transfer mechanism; UV energy radiating from the "light bulb" would not couple well with hydrogen gas, so most of the energy would be wasted. Water might work a bit better (and also has advantages of being easily available and eliminating the need for cyro coolers and heavily insulated tanks), but would probably be pretty corrosive in that sort of environment.

Robbie said...

What I want to know is how would civilians get into space? Right now the only way for a civie to be sent into orbit is wave 20 million in front of the Russians, and you gotta be filthy rich to blow 20 million in one shot. So how could the average Joe hitch a ride to LEO for a nice week in space, and not have to be Donald Trump to pay for it?

Citizen Joe said...

Re: Reality vs. speculation...
I like to take cues from Nature and the fallibility of Man. For example: We know that fusion works because the Sun exists as a natural example. The sun uses gravity for containment, which isn't very efficient but it is also burning significantly more difficult fuels. It is also easy to demonstrate that magnetism is stronger than gravity, as demonstrated with a simple magnet. So it stands to reason that a fusion reactor is possible with sufficient engineering and experimentation. Thus, my future settings are populated by fusion reactors for power.
Where the Fallibility of Man comes into play is that we have repeatedly made assumptions that the Universe is one thing and then later those assumptions are proven wrong... or incomplete. A prime example is gravity. While we can model it and observe its effects, we don't actually know what it is. Likewise, there is evidence that space itself is expanding at superluminal speeds. Combine the theory that matter warps space which produces the effects we call gravity, plus the space expansion and throw in some dark matter/energy, etc. and it is easy to have space warping technologies. However, if you have the technology to finely manipulate space so as to have artificial gravity, then there are going to be other space warping application.

Luke said...

Thucydides:

UV light with a wavelength shorter than 80 nm (corresponding to the binding energy of the bonding electron orbital of the H_2 molecule - 15.43 eV) will be readily absorbed via the process of photo-electric absorption. The molecular hydrogen gas will be transparent to light with a longer wavelength. To get the peak of your thermal emission in wavelengths shorter than 80 nm you need temperatures greater than 35,000 K, and you will be radiating at an intensity of nearly 10 GW/m^2 (assuming your uranium vapor core is optically thick - which it is likely to be at wavelengths shorter than 80 nm). A necessary consequence is that with a minimum amount of uranium for the method to work at all (the critical mass), you end up with very high power levels or none at all.

An alternate method is to absorb the light with something else (such as tungsten or carbon - tungsten is slightly superior as far as not evaporating as much, but carbon is lighter). Then use this as a heat exchanger to heat the hydrogen via conduction. This has the disadvantage that your exit temperature can never get higher than what the heat exchanger can withstand (about 3,500 K for W before sublimation becomes a major issue, a bit less for C). With a nozzle efficiency of 70%, 3500 K corresponds to an exhaust velocity of 5.5 km/s for molecular hydrogen.

Tony said...

Jim Baerg:

"So there is some chance that a crash of the Liberty Ship nuclear rocket would release some radioactivity that might kill somebody. If that makes it unethical to use such a rocket then it is also unethical for me to drive a car since it might collide with someone or the exhaust could cause cancer in people who breath it in.

Do you think that a death due to something to do with nuclear power is somehow worse than a death due to other causes?"


It's a cost-benefit decision, Jim. Humans, as a community, have decided the costs of motor vehicle transportation are offset by the benefits. We have also decided that the costs of atmospheric releases of radioactives are not worth the benefits. That is what is ethically obtuse about the man's position -- he equates motor vehicles with flying nuclear reactors and hadwaves away the community consensus that they are not equivalent. That's also what makes it sophistry -- it's pathos wrapped up in the mantle of logos.

Tony said...

Ferrell:

I'll take your condemnation on directly: human spaceflight advocacy can no longer stand well-meaning but ignorant enthusiasts. We have humored them long enough. We need to scrape them off and tell them to come back only when they have a realistic understanding of physics and engineering. And I really don't care how many would-be allies that discourages or disillusions. The minority that it challenges to do better will return to the fold stronger and ultimately more effective.

Tony said...

Robbie:

"What I want to know is how would civilians get into space? Right now the only way for a civie to be sent into orbit is wave 20 million in front of the Russians, and you gotta be filthy rich to blow 20 million in one shot. So how could the average Joe hitch a ride to LEO for a nice week in space, and not have to be Donald Trump to pay for it?"

There. Is. No. Way. For the next several hundred years (at least) humanity will be billions of horseholders for a few dozen, then a few hundred, and maybe eventually a few thousand paladins. It's best you come to terms with that right now, and decide whether you want to be involved in the enterprise, set yourself against it, or just keep out of the way.

Now that I've got the bitch-slap reality check out of the way, let me encourage you by saying that over the last forty years human spaceflight has, for me, been quite an entertaining spectator sport, worth every moment and every tax dollar I've spent on it. It can be for you too.

Raymond said...

Luke:

You sure on that 5.5 km/s number? NERVA got eight and change from H2 with core temp between 2000-2200 K.

Tony, Jim Baerg:

I thought the guy's real sophistry was his assertion that atmospheric tests didn't kill anyone (as discussed earlier, we have reason to believe they did) and his incredibly disingenuous claim that "we mitigated the risk", which shows a staggering lack of understanding of risk management. Then he brought in the Shuttle's launch safety (ironic or sad?) and tried to equate the release of hydrofluoric acid with the release of gaseous radioactive elements.

For the optimists:

The only scenario I can think of which would substantially improve the tempo of space travel would be if saturated palladium hydride turns out to be a very high temperature superconductor, as recent initial study has hinted it may be. (Note that this is a very big if.) Deposits of palladium in the Earth's crust are due to asteroid impacts, since the platinum group metals were mostly dragged into the core during the Earth's formation, and thus planetary reserves are rare. Right now they are sufficient, since industrial and electronic uses are for small quantities, but a room-temp superconductor would have a staggering number of applications in quantities which would perhaps make it economical to extract it from metallic asteroids. Maybe.

Luke said...

Raymond,

Now that i think about it, I might have been off by a factor of sqrt(2) - I didn't take the two rotational modes or one vibrational mode into account. So here's the argument: If you heat up one mole of H_2 to 3500 K, the total energy in every "quadratic degree of freedom" is 0.5 R T, where R is the gas constant (R = 8.3 J/mol/K) and T is the temperature (3500 K in this case). Any gas has three translational degrees of freedom (motion along the x, y, and z axes). A diatomic molecule also has two rotational degrees of freedom (rotation along each of the two directions perpendicular to the axis of the molecule) and one vibrational degree of freedom (vibration along the one molecular bond) for a total stored energy of 6 x 0.5 R T. If you heat the hydrogen up to 3500 K, and then let it expand through a rocket nozzle, conservation of energy tells you that if all of your stored thermodynamic energy becomes kinetic energy of a very cold gas, the final kinetic energy will be 6 x 0.5 R T per mole. We know that the kinetic energy of a mass M moving at velocity V is 0.5 M V^2. This means that the maximum exhaust velocity possible under this assumption is V = sqrt(6 R T / M). The molar mass of hydrogen is 0.002 kg, so if we plug all this in, we get 9300 m/s.

Now let's look at our assumptions. First, it is only the translational modes that directly give you your exhaust velocity - this is when the atoms moving in one direction bounce off of the nozzle so they end up moving backward. This means that in order to use the energy of the rotational and vibrational modes, you need to have many collisions between the molecules in the process of expansion in the nozzle so that they can transfer their energy to the translational modes. This is not always a good approximation for the vibrational modes - at least for some chemicals (hydrogen fluoride, oxygen iodide) expansion of the hot gas through a supersonic nozzle leaves the vibrational modes still "full" of the energy they had. I'm not sure if this is also true for hydrogen dimers.

Second, we assumed that no energy was being added to the gas during the time when it was expanding. Since the expanding gas is becoming colder, in principle you could conduct heat to it as it accelerated while keeping the temperature the same. This would allow you to reach higher exhaust velocities, since you are continually adding energy.

Third, we assumed that the spent propellant gas put all of its energy into the final kinetic energy so that it ends up with zero temperature. In practice, this will not happen - the atoms in the propellant gas will exit with a range of velocities because of the initial thermal distribution of velocities, and some of those atoms will be going a bit off to the side instead of straight back. These were some of the factors I included in my "nozzle efficiency", which for a well designed solid rocket nozzle can reach 70%.

If we neglect the second assumption, this indicates that the range of velocities available for the 2200 K NERVA are 5.6 km/s to 7.4 km/s. If they actually achieved 8 km/s it looks like they were heating the gas as it expanded (at least, that's my best guess as to what they were doing).

Raymond said...

Luke:

9300 m/s sounds better. The 2200 K was for the core, not the throat, so the temperature for your calculations would probably be higher.

I've got a big long NERVA document with all their test results summarized - any way I can get your email and send it along?

Geoffrey S H said...

@ Tony.

I say what I am about to say with the utmost, utmost respect here, and with no wish to create a heated debate. If it sounds strong, please, please bear in mind there I feel a great need tp ask this and clear things up. If this sounds too strong to everyone, then I completely understand and apologise in advance.

Here goes:

I guess that applies to science fiction writers too, and some of us here- since they are providing truths and untruths of the public that influence the enthusiasts. The market that creates "well-meaning enthusiasts" is immense and damaging to the industry.

Given that I have not devoted what I have of my life to NASA grade engineering and maths (but could, though that probably would not be enough)- count me out. :(

I will leave one last thought then:

What happens if the rocketpunk future is moved foreward to ten thousand years' hence? Heretical, yes, and an almost impossible world-buidling excercise.

But one might be optimisitc and imagine rocketpunk scale infrastructure then...

Done. Apologies in advance.

Geoffrey S H said...

@ Robbie.

"What I want to know is how would civilians get into space? Right now the only way for a civie to be sent into orbit is wave 20 million in front of the Russians, and you gotta be filthy rich to blow 20 million in one shot. So how could the average Joe hitch a ride to LEO for a nice week in space, and not have to be Donald Trump to pay for it?"

What would be your time frame? Hundreds or thousands of years?

Anonymous said...

"Though, to be honest, the concept and base technology for rotovators and skyhooks sounds more ideal then a space elevator since what is needed is a hypersonic aircraft to lift payload to the required altitude."

But why? Can't the skyhooks rotate counter to their orbits, so that at the bottom of their swing their grapple is motionless? I've seen that described lots of places.

Then they can grab Bigelow modules lofted up by those giant JP Aerospace balloons that they show pictures of on their website.

Luke said...

Raymond,

Sure, it is lwcamp at gmail dot com.

Jim Baerg said...

Tony Nov 19 9:29 am: "It's a cost-benefit decision, Jim."

A lot of cost-benfit decisions seem to be made on faulty assumptions. Human gut feelings about relative risks are usually way out.

Consider the relative risks of driving vs flying a given distance. Driving is actually more dangerous, but flying is feared more.

Then there is the irrational fear of nuclear power. Even if you make pessimistic assumptions about the harm from low level radiation, the deaths from Chernobyl are exceeded many times over by coal plants running normally. However, which power source is protested against?

Maybe the nuclear rocket would be unreasonably hazardous, but I'm not going to make a knee jerk assumption that the hazard cannot be made no worse than many that are accepted.

Tony said...

Geoffrey S H:

"I guess that applies to science fiction writers too, and some of us here- since they are providing truths and untruths of the public that influence the enthusiasts. The market that creates "well-meaning enthusiasts" is immense and damaging to the industry.

Given that I have not devoted what I have of my life to NASA grade engineering and maths (but could, though that probably would not be enough)- count me out. :( "


I don't have a problem with science fiction or science fiction authors. I read a lot of SF. There's nothing wrong with it -- it's just entertainment. What I'm advocating is being way less understanding and accomodating of people who don't comprehend that it's just entertainment, and who won't adopt a realistic attitude when it's time to have a serious discussion.

And you don't have to devote your whole life to it. Just spend an hour or two each week studying a non-fiction, non-speculative source. I recommend astronautix.com as a good place to start. Also, get yourself a copy of Bate et. al. Fundamentals of Astrodynamics. You can understand most of it if your math level is college algebra, though calculus helps.

Tony said...

Jim Baerg:

"A lot of cost-benfit decisions seem to be made on faulty assumptions. Human gut feelings about relative risks are usually way out."

I have to concur with Raymond that this attitude is way out in terra incognita WRT rational risk management. Just because we accept some risks doesn't mean we have to add others to them. And people work every day to mitigate risks that already exist. Nuclear fision rockets coming and going from the Earth's surface are not an existing risk to be mitigated. It is an additional risk that we don't need to accept in the first place.

And I think a lot of people here would appreciate it if you didn't insinuate that people that disagree with you are irrationally afraid of nukes. Nuclear power on ships and nuclear power on land are existant applications with a very low associated risk. Nuclear power for interplanetary spaceflight is higher risk, but limited to launch only. (As we've discussed recently, flight rules can and probably will be made such that space reactors are never put in an orbit that can intersect the Earth or its sensible atmosphere.) Flying nukes coming and going? That's a species of risk so far beyond any of the others already mentioned that it's in it own distinct category. And yes, I would put it up there with atmospheric nuclear testing.

Elukka said...

By that logic we'd never have developed any new technology because at the time it'd have been a new, additional risk.

I don't think you can put it anywhere near atmospheric nuclear testing. Is a large nuclear release on purpose really equivalent to a likely much smaller release that only occurs in case of catastrophic failure?

I also think there needs to be a real risk analysis of the particular nuclear rocket before we can say whether the risks are worth it. I don't know what kind of analysis was done on NERVA, but clearly they didn't determine it was too risky.

Tony said...

Elukka:

"By that logic we'd never have developed any new technology because at the time it'd have been a new, additional risk."

That's a non sequitur. Many technologies are developed to reduce risk. In fact, historian Ian Morris suggests that social and technical advancement arises out of three universal human traits: laziness, fear, and greed. We want safer things that will make life easier and bring in some lettuce while we're at it.

"I don't think you can put it anywhere near atmospheric nuclear testing. Is a large nuclear release on purpose really equivalent to a likely much smaller release that only occurs in case of catastrophic failure?"

It's precisely the same thing if you look at the underlying motivation of the atmospheric test ban. Remember, it was designed to ensure that no atmospheric release of high energy radioactives could be possible. A lot of the operational safety policies for nuclear power reactors are built around this principle as well. And by that principle, flying around nuclear reactors with gaseous radioactives in side them just doesn't fit the profile.

"I also think there needs to be a real risk analysis of the particular nuclear rocket before we can say whether the risks are worth it. I don't know what kind of analysis was done on NERVA, but clearly they didn't determine it was too risky."

It was just un-risky enough, because the fuel elements and the overall reactor design were robust under stress. A reactor loss failure in flight would most likely lead to an intact impact with little or no dispersion of relatively large, solid radioactive elements. With a gas core reactor...not so much.

Elukka said...

Some technologies may be developed to reduce risks, but cars and planes, for example, both introduced further risks that didn't exist before.

I don't think an atmospheric release of radioactives is inherently worse than an atmospheric release of other pollutants. The severity of it is what matters.

Couldn't you encase the gas core reactor (and particularly the waste products) in whatever material it is that makes NERVA so robust? It'd be a mass penalty, but when you have 30 km/s exhaust velocity to play with...

If gas cores do end up deemed too unsafe if there ever is a real risk analysis done (if we can even build them, that is), we still have solids. There's also something called a thin-film fission fragment NTR, but it sounds like it could have radioactive exhaust. Can't find anything about it but references in other documents.

Tony said...

Elukka:

"Some technologies may be developed to reduce risks, but cars and planes, for example, both introduced further risks that didn't exist before."

At greatly increased convenience and no small profit. Remember, it's not just fear that motivates progress, but laziness and greed as well. Those motives don't apply to nuclear Earth-to-orbit shuttles. Before you go there, no, there is no pie in the sky that will make them profitable enough or convenient enough to justify the risks.

"I don't think an atmospheric release of radioactives is inherently worse than an atmospheric release of other pollutants. The severity of it is what matters."

Actually, it is. Even the most toxic and slowly-decomposing chemicals don't have radioactive half lives of hundreds or thousands of years.

"Couldn't you encase the gas core reactor (and particularly the waste products) in whatever material it is that makes NERVA so robust? It'd be a mass penalty, but when you have 30 km/s exhaust velocity to play with..."

The robustness of solid core reactors under dynamic stress is attributable to the mechanical properties of the fuel elements themselves. With a gas core reactor, well, the core is gaseous. If containment is broken -- and in a catastrophic vehicle loss, it most likely would be -- the gaseous radioactives would be released in the environment.

Sabersonic said...

But why? Can't the skyhooks rotate counter to their orbits, so that at the bottom of their swing their grapple is motionless? I've seen that described lots of places.

From what little I know of orbital mechanics, hypersonic velocities remain the same no matter the direction of orbit compared to the rotation of the planet or other such celestial bodies. Meaning that the grapple point of rotovators and sky hooks are not "motionless" but still moving at high enough speeds.

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Citizen Joe said...

I did some calculations on the 'stationary' rotovator. While horizontally, the end of the tether would be stationary, the vertical movement would be very fast and result in excessive g forces... I want to say like 100 G's

Anonymous said...

Tony said (in response to Elukka):
"Actually, it is. Even the most toxic and slowly-decomposing chemicals don't have radioactive half lives of hundreds or thousands of years."
And yet Mercury is forever...releaseing nonradioactive heavy metals into the atmosphere is generally considered to be a bad thing, yet we release all kinds of stuff into the air every hour of every day...including radioactive isotopes from the burning of organic matter and fossil fuels. Your "zero risk" approch to nuclear flight isn't realistic, just 'road-blocking'. Sorry if this annoys you, but it's just my opinion of what your comments sound like to me...:(

Ferrell

Citizen Joe said...

Ya, you don't want to go on the 100% green idea. Mother Nature herself isn't 100% green, look at volcanoes for instance. The question isn't whether you're polluting but rather how long will the biosphere take to recover. The same can be said for artificial environments like on a space ship. If your life support can recover from a cigarette in eight hours, then up to four could be smoked in a day (assuming no other shocks to the system). However, if 30 people were smoking, then the life support would be overwhelmed quickly.

In the case of the Liberty Ship, the environmental impact would be standard impact from an event free mission plus the chance of a catastrophic failure times the effects of such a disaster.

Raymond said...

Ferrell:

"...yet we release all kinds of stuff into the air every hour of every day...including radioactive isotopes from the burning of organic matter and fossil fuels."

A) Those sources aren't in the concentrations which would happen with an explosion of a gas-core nuclear rocket. We'd be talking Chernobyl in scale; that event killed an estimated 4,000 people from cancer and contaminated a wide swath of farmland.

B) What makes you think I'm not against coal plants for that very reason?

Thucydides said...

A little history of the Nuclear Light Bulb here:

http://up-ship.com/blog/?s=nuclear+light+bulb

I noticed that in the Atomic Rockets site this kind of engine is listed as not capable of lift off from Earth (T/W <1), but the Nomograms seems to indicate it is capable of liftoff. The amount of machinery needed to control the reaction and contain the radioactive material probably would raise the mass beyond practical thrust/weight ratios for liftoff, but it would make a heck of an interplanetary drive.

Tony said...

Ferrell:

"And yet Mercury is forever...releaseing nonradioactive heavy metals into the atmosphere is generally considered to be a bad thing, yet we release all kinds of stuff into the air every hour of every day...including radioactive isotopes from the burning of organic matter and fossil fuels. Your "zero risk" approch to nuclear flight isn't realistic, just 'road-blocking'. Sorry if this annoys you, but it's just my opinion of what your comments sound like to me...:("

We don't fly around hundreds of pounds of gaseous mercury, do we? Name me a community that would allow it. In fact, most countries are restricting the manufacture and use of products containing mercury. Norway has banned their manufacture and import altogether. When I worked in safety management for a major hospital company in the 1990s, there was a big push within the organization to eliminate mercury thermometers and manometers. They represented too great a hazmat issue if their mercury contents were released.

Then there's the radiation precautions we took in the hospital with nuclear medicine deliveries. We made sure the deliveries were made through a single entrace that had a radiation sensor. All linen and garbage from the Nuclear Medicine departemtn were also removed past this sensor, to make sure they were safe. The nuclear medicine suppliers carried the stuff around in lead-lined cans, and it was stored on the premises in lead-lined safes. And this was justified. As Wikipedia states:

"A radiotherapy machine may have roughly 1000 Ci of a radioisotope such as cesium-137 or cobalt-60. This quantity of nuclear material can produce serious health effects with only a few minutes of exposure."

So I don't think your cavalier attitude about heavy metal or radioactive safety has much in common with actualy regulatory or industrial practice.

Tony said...

Re: Ferrell

Addendum (this occurred to me on the way to work today):

The amount of radioactivity released from burning fossil fuels can't be that much. As you may know, steel from ships sunk or scuttled before 1945 is a highly valuable commodity for making instruments that measure radioactivity. Why? Because there was very little radioactive material in the air when it was made, thus it didn't take up radioactive materials when it was smelted. This, of course, is after millenia of fossil fuel burning, including quite extensive burning in the decades immediately prior to when the most prized ships -- WWI and WWII German warships -- were built.

Also, all of that good German steel was made with coke from coal, a lot of it. Yet despite close contact with a material that is supposedto release radioactive trace elements when burned, guess what? The steel is still radioactively "clean".

Something just isn't adding up here...

Citizen Joe said...

The nuclear light bulb has a Thrust to weight ratio of about 0.9. That means that it doesn't quite have enough to lift itself alone off of Earth. Lift off rockets need closer to 10.0 thrust to weight ratio because they also need to lift the payload and propellant.

Anonymous said...

Tony said:"The amount of radioactivity released from burning fossil fuels can't be that much. As you may know, steel from ships sunk or scuttled before 1945 is a highly valuable commodity for making instruments that measure radioactivity. Why? Because there was very little radioactive material in the air when it was made, thus it didn't take up radioactive materials when it was smelted. This, of course, is after millenia of fossil fuel burning, including quite extensive burning in the decades immediately prior to when the most prized ships -- WWI and WWII German warships -- were built."

See, when you write like this, you sound rational, reasonable, and thoughtful...however, this wasn't what I was responding to; too often you do sound like you are simply attacking people because you don't agree with them. And, for the record, I'm not 'cavalier' about the enviornment; I just don't panic at every instance of a negative impact; I evaluate the severaity of each event.
And..."Also, all of that good German steel was made with coke from coal, a lot of it. Yet despite close contact with a material that is supposedto release radioactive trace elements when burned, guess what? The steel is still radioactively "clean"."
No, it's not. It has the same level of background radiation as any other example of steel made at that time or before over the last several centuries. You, yourself, are slightly radioactive, just as we all are. Again, no matter how much you deny it, you keep letting slip your phobia about radiation. Please, and I'm sure that others would appreaseate it as well, just try to keep it from overwhelming your writing.

Ok, I'm going to have to stop responding to Tony's comments...sorry.

Anyway, back to the topic at hand...I'm sure that there will be either refinements to space launch technology or an innovation in the business of space in the next few years to decades that would allow better access to orbit. An expanded or more vocal (or both), base of supporters would certainly keep the politicians listening...whether they hear what we're saying is another thing altogether. Exploring NEO's, satillite security, search-for-life-out-there, a new type or class of satillite, or even a renewed "space race" with the emerging 'space powers' are all possiblities that could spur such an effort to reduce launch costs and/or launch efficency. Again, whether this is due to new technology or a change in the way businesses approch launch costs, either one should result in increased launch tempo, reduced launch costs, or both. The new tech could be something as simple as using newer, cheaper, lighter, and/or better quality materials in the most expensive parts of the rocket (i.e. the engines/electronics), a dramatic increase in relibality without an increase of costs, or some other innovation we aren't yet aware of. From the pace of materials science recently, I'd bet on a material that is stronger, lighter, and cheaper than is currently available, will be used in aerospace applications (including rockets), in the comming decades; certainly by mid-century. Without changing the basic technoloy of rocketry, the use of lighter, stronger, cheaper materials to build them (and increase reliability at the same time), will drive down costs.

Well, I've got mundane tasks to do, so...

Ferrell

Anonymous said...

Tony said:"The amount of radioactivity released from burning fossil fuels can't be that much. As you may know, steel from ships sunk or scuttled before 1945 is a highly valuable commodity for making instruments that measure radioactivity. Why? Because there was very little radioactive material in the air when it was made, thus it didn't take up radioactive materials when it was smelted. This, of course, is after millenia of fossil fuel burning, including quite extensive burning in the decades immediately prior to when the most prized ships -- WWI and WWII German warships -- were built."

See, when you write like this, you sound rational, reasonable, and thoughtful...however, this wasn't what I was responding to; too often you do sound like you are simply attacking people because you don't agree with them. And, for the record, I'm not 'cavalier' about the enviornment; I just don't panic at every instance of a negative impact; I evaluate the severaity of each event.
And..."Also, all of that good German steel was made with coke from coal, a lot of it. Yet despite close contact with a material that is supposedto release radioactive trace elements when burned, guess what? The steel is still radioactively "clean"."
No, it's not. It has the same level of background radiation as any other example of steel made at that time or before over the last several centuries. You, yourself, are slightly radioactive, just as we all are. Again, no matter how much you deny it, you keep letting slip your phobia about radiation. Please, and I'm sure that others would appreaseate it as well, just try to keep it from overwhelming your writing.

Ok, I'm going to have to stop responding to Tony's comments...sorry.

Anyway, back to the topic at hand...I'm sure that there will be either refinements to space launch technology or an innovation in the business of space in the next few years to decades that would allow better access to orbit. An expanded or more vocal (or both), base of supporters would certainly keep the politicians listening...whether they hear what we're saying is another thing altogether. Exploring NEO's, satillite security, search-for-life-out-there, a new type or class of satillite, or even a renewed "space race" with the emerging 'space powers' are all possiblities that could spur such an effort to reduce launch costs and/or launch efficency. Again, whether this is due to new technology or a change in the way businesses approch launch costs, either one should result in increased launch tempo, reduced launch costs, or both. The new tech could be something as simple as using newer, cheaper, lighter, and/or better quality materials in the most expensive parts of the rocket (i.e. the engines/electronics), a dramatic increase in relibality without an increase of costs, or some other innovation we aren't yet aware of. From the pace of materials science recently, I'd bet on a material that is stronger, lighter, and cheaper than is currently available, will be used in aerospace applications (including rockets), in the comming decades; certainly by mid-century. Without changing the basic technoloy of rocketry, the use of lighter, stronger, cheaper materials to build them (and increase reliability at the same time), will drive down costs.

Well, I've got mundane tasks to do, so...

Ferrell

Tony said...

Ferrell:

"too often you do sound like you are simply attacking people because you don't agree with them."

What's the point in commenting about something you agree with? Chirping "Me too!" is a waste of bandwidth.

And I'm not attacking people. I'm trying to discredit ideas I perceive to be ignorant. If people take that personally, that's because they choose to be offended, not because I am trying to offend them.

"And, for the record, I'm not 'cavalier' about the enviornment; I just don't panic at every instance of a negative impact; I evaluate the severaity of each event."

Sorry if my opinion hurts your feelings so much, but from the perspective of somebody who has actually done safety management, including heavy metals and radioactives, your attitude is almost ridiculously cavalier. And from your contributions here, it seems that you have no idea of what the actual risks are.

"No, it's not. It has the same level of background radiation as any other example of steel made at that time or before over the last several centuries. You, yourself, are slightly radioactive, just as we all are. Again, no matter how much you deny it, you keep letting slip your phobia about radiation. Please, and I'm sure that others would appreaseate it as well, just try to keep it from overwhelming your writing."

I don't have a phobia about radiation. I'm so non-phobic, as a matter of fact, that I upset a lot of people hereabouts by actually supporting what Energy Solutions wants to do with low grade radioactive waste in Utah. It would be a greater advantage to the state tax base at relatively low risk.

I also served aboard a nuclear wessel (USS Long Beach) for two years without panic or even a mild unease. In fact, I thought it was pretty cool, compared to other ships I drifted around on. We never had fresh water rationing, something not always true about serving on fossil-fuelers.

But I don't let my general approval of the safe operation of nuclear power reactors cloud my judgment. Some actions and some risks are simply irresponsible. Risking large scale atmospheric release of radioactives falls into this category.

Citizen Joe said...

I'd say you're both wrong. :)

Actual danger from radiation isn't the problem, it is the perceived danger which will skunk the project. It will be hard enough to get the trillions of dollars out of the tax payers, if there is even a hint of radiation, they will waiver. John Q. Public doesn't understand radiation, but Hollywood has told him that it is bad. It doesn't matter that we're talking less than that coming off a microwave oven (and we're not). Throw the term Uranium at him and he'll think nuclear bomb or Chernobyl. NASA isn't allowed to send up any more RTG's because of that fear.

So, it isn't actual danger, it is perceived danger.

Anonymous said...

Citizen Joe said...

I did some calculations on the 'stationary' rotovator. While horizontally, the end of the tether would be stationary, the vertical movement would be very fast and result in excessive g forces... I want to say like 100 G's


I'm too lazy to try the math for a rotating rotovator (I should electrocute my testicles as punishment), but I DID download a file from Tethers Unlimited (named MXERJPC2003Paper.doc, but I'm too stupid to have recorded the URL), and throughout they make references to only 2Gs of acceleration at the tip:

Page 7:
It must be able to support the mass of the payload at up to 6 gees of acceleration (2 gees nominal acceleration due to tether rotation, plus 50% due to capture dynamics, multiplied by a safety factor of two).


and

Page 10 (Table):
Rendezvous acceleration 2.32g


and

Page 5
Because plasma contactors require expenditure of propellant, and because the GridSphere concept may require significant additional mass to enable it to maintain its shape under the 2-gees of acceleration it will experience near the tether tip, we currently favor the bare wire tether approach.

Anonymous said...

I found it by clicking with my mouse; I didn't even have to use two hands to type:

http://www.tethers.com/papers/MXERJPC2003Paper.pdf

Anyway, wouldn't 2Gs of acceleration at the point of grapple be low enough to let my granny (if she weren't long dead) float up on a JP Aerospace balloon, and swing up into orbit?

Tony said...

Citizen Joe:

"So, it isn't actual danger, it is perceived danger."

Sorry, but that's incorrect. It's not the danger of zero or minimal radioactive release in normal operations that's the problem. It's the risk of serious primary contamination over a large area, and increased atmospheric contamination, in the event of a vehicle loss in powered flight. Given the history of rocketry, the loss of a vehicle in powered flight isn't even a remote risk. The probability approaches 1.0, regardless of the care taken in design, fabrication, operations, and maintenance. I don't care who you are, even a crazy nuclear science teacher that wears dark glasses, you aren't going to risk an almost certain Chernobyl level incident in the name of space progress.

Citizen Joe said...

And that is the PERCEIVED danger. It could be real. It could simply be exaggerated. But so long as people perceive a space ship as a nuclear time bomb, it ain't gonna fly.

I think the 2G rotovator is a moving one and moving VERY fast. I think that a combination of a rotovator and the Loftstrom Loop might do what we're looking for. The loop could be controlled precisely so as to launch payloads just right so that the inbound rotovator can capture them and lift them into appropriate orbit. Basically it creates a first and second stage boosters for packages. All I can say is that is not something that you eyeball and it would be a helluva ride.

Tony said...

Citizen Joe:

"And that is the PERCEIVED danger. It could be real. It could simply be exaggerated. But so long as people perceive a space ship as a nuclear time bomb, it ain't gonna fly."

How is that a perception? It's a fact that a gas core nuclear rocket would, in operation, include tens to hundreds of kilograms (at least) of gaseous uranium or plutonium. It's a fact that with any kind of regular use, a vehicle or vehicles will be lost in flight. It's a fact that such a loss would likely cause the atmospheric release of tens to hundreds of kilograms of radioactive materials in gaseous form. It's a fact that such a release would contaminate a large area and pose a human life hazard to anybody who didn't evacuate quickly. It's possible that some -- even many -- people would become sick or even die before they could be evacuated. There is no perception involved in any of that.

Scott said...

It's a fact that such a loss would likely cause the atmospheric release of tens to hundreds of kilograms of radioactive materials in gaseous form. It's a fact that such a release would contaminate a large area and pose a human life hazard to anybody who didn't evacuate quickly.
Sorry, put me in the camp of one who believes that nuclear power is probably a good thing for getting useful loads up to space until we figure out magitech supercarbon for orbital elevators.

Even *in-ground* nuclear testing ends up releasing uranium vapors. Coal-fired powerplants release radioactive gasses, in larger quantities than even one catastrophic rocket accident per year.

Since coal-fired powerplants are acceptable to the public, the challenge is to get the knee-jerk reaction to "radiation is da debbil!" to go away.

Tony said...

Re: Scott

I think there's a serious disconnect between what pro-nuke advocates (of all types, not just rocketry) want you to believe and what is factual. As previously mentioned, millenia of fossil fuel burning did not put as much radiation in the atmosphere as nuclear testing did in 20 years. The difference is so distinguishable that instrument makers will pay a premium -- and a high one -- for pre-1945 steel.

When you have (highly convenient) claims on one side, and economic fact on other, guess which I think one should choose as a basis for analysis.

As also previously pointed out, I used to work in hospital safety management. Now, I don't know about other organizations, but we certainly didn't stand for "well, a little bit won't hurt" type thinking. And that certainly wasn't the attitude onboard the Long Beach.

I can't stop you from believing what you want to believe. But I can certainly inject a sense of reality for those who want to consider the facts.

Citizen Joe said...

Until a nuclear spacecraft ACTUALLY explodes, scattering radioactive debris and indisputably kills or contributes to the death of millions, it will only be the perception that such a thing could happen. I'm not saying that isn't the likely outcome, just that the perception of such an event in the minds of the general populace (and the decision makers) will prevent moving forward with such a device.

In order to put such a device into operation you need two things:
1) Very good engineers that build in enough safety features that it will never blow up.
2) Total lock down on all information about the project so that nobody ever knows.
The big problem is that closed societies don't lend themselves to the former.

Anonymous said...

Citizen Joe said...

I think the 2G rotovator is a moving one and moving VERY fast.


Oh yeah. You're right. The paper I cited said it's moving an nearly 18,000 mph. Oops.

Raymond said...

"Perception" carries an implication of inaccuracy, ignorance, superstition, or all three. I don't think it's particularly fair or useful to lump rational risk management in with such a label. We're not talking vague projections or mad prophecies here, nor simplistic "nukes = badness" positions. We're talking radiation dosage effects and dispersion models, contamination projections and epidemiological analysis. We have similar events to compare with, documentation of their effects, and extrapolations of failure probabilities. We're not exactly crossing ourselves and throwing salt over our shoulders.

We've also gotten into this debate over the safety while ignoring the technical problems with the very concept. Nuclear-thermal propulsion (in its various possible forms) may make a decent cislunar and/or slow interplanetary drive, but it's not terribly useful as a first stage. Thrust-to-weight is still an order of mag less than chemfuel, specific power is at least as far behind, and the same material technologies that would allow for a halfway workable gas-core engine would also give us chemical engines of even better service life (while being lighter, cheaper, easier, and safer to boot).

Gas-core nuclear engines aren't the magic bullet for lowering space access costs. I'm not sure there is one. You pay the (massive) cost upfront, or by installments. You can hope for a breakthrough (or even work towards one if you're in the appropriate field). Maybe we'll get lucky with Heim theory and get cheap antigrav (and FTL to boot). But it's going to take more than just building a nuclear-powered skyscraper to kickstart the Interplanetary Age.

Raymond said...

On a slightly lighter note:

Scott said "...radiation is da debbil!"

Let's see:

- Corruption of the flesh? Check.
- Unseen cause of sickness and death? Check.
- Contamination of all it touches? Check.
- Can be warded off by earth metals? Check.
- Deforms, mutilates and curses children not yet born? Check.
- Misunderstood by lay people? Check.
- Can grant great power if caged appropriately? Check.

I think it may meet the criteria...

Jim Baerg said...

Tony: A clarification on the coal plants emit radioactivity claim.

Most coal contains small amount of uranium & thorium & when coal is burned it goes out in the fly ash. There is a lot of radioactivity inside a nuclear power plant, but it mostly stays inside, so a coal plant *emits* more radioactivity than a nuclear plant per unit energy produced. OTOH an atmospheric nuclear bomb test dumps all the raioactivity into the atmosphere, so both your comment about pre 1945 steel & the coal emits radioactity can both be true.

Thucydides said...

Re-reading the post on Up-ship on the history of the nuclear light bulb makes it seem even more improbable, outside of the release of radioactive material issue. One possible design would have to deal with Fluorine gas at several thousand degrees C? The quartz shell has to be kept above 800 C so it won't blacken and absorb the thermal energy, but must be kept below 1100 c so it won't disintegrate due to thermal stress?

Compared to those issues, IEC nuclear fusion seems to be a slam dunk (even given the speculative nature of the current design).

Complex machinery like nuclear light bulbs, LACE/Skylon engines, civil engineering into space and so on won't pass the sniff test anyway; you are asking people to trust fortunes and lives to complex and cantankerous machinery. Even Chief Engineer Scott wold probably balk at this stuff.

If we are going to get anywhere with the "First Step", we need to identify cheap, robust and reliable technologies, and ideally things that can be repurposed easily. A BDB like Aquarius that makes it into orbit is essentially a big silo which *might* be usable as construction material or living space (I usually visualize a team of workers inflating a balloon inside the empty fuel tank and hardening it with a layer of epoxy). Laser thermal "Lightcraft" are another means of creating a rugged space launch vehicle with relatively benign failure modes.

This also favours the trope I applied in the Industrialization of space post; technology will be ruthlessly stripped down to the simplest equipment and technologies that can be made and supported locally; solar thermal vs photovoltaic, a really limited set of instructions and parts for the CNC milling machines/replicators, plastic bags full of water vs cyrogenic LH2 (and colonies made from bags of water ice vs concrete Island 3 structures).

Realpunk using these tropes can be just as interesting as Rocketpunk, stories are about people in unusual settings or situations, we just have to think of *how* different these settings or situations will be.

Geoffrey S H said...

Thucydides:

"Laser thermal "Lightcraft" are another means of creating a rugged space launch vehicle with relatively benign failure modes."

I'm curious as to how you can see anything about a light-craft as even remotely "benign". A massive laser to propel it up through the athmosphere means that it could be weaponised with depressing ease. It seems to me that sch a craft will be avoided just as much as a nuclear rocket.

Not to mention that the payload would be miniscule.

Citizen Joe said...

Lightcraft would solve two problems at once if your objective is beamed solar power. First you need the technology to lift the light craft (beamed power). If you've solved that, then implementing that design to beam the solar power back to Earth should be relatively easy.

Of course, preventing the energy satellites from being turned into weapons is the hard part. Fortunately, the deep space treaty has prevented the placement of lasers in space.

Tony said...

Jim Baerg:

"Most coal contains small amount of uranium & thorium & when coal is burned it goes out in the fly ash. There is a lot of radioactivity inside a nuclear power plant, but it mostly stays inside, so a coal plant *emits* more radioactivity than a nuclear plant per unit energy produced. OTOH an atmospheric nuclear bomb test dumps all the raioactivity into the atmosphere, so both your comment about pre 1945 steel & the coal emits radioactity can both be true."

I'm not disputing that coal and coal smoke contains radioactive trace elements. I'm disputing that it's all that much. As I stated earlier, pre-1945 steel was made in an environment of intensive fossil fuel burning and its manufacturing process included close and continuous contact with coke made from coal. Yet it is still considered radiologically "clean" for instrument making purposes, compared to post-1945 steel. That should tell you something about just how much radiatioactive material was dumped into the atmosphere by nuclear testing.

It should also tell you, if you think a bit, about how serious nuclear plant operators are WRT radiation safety. They can run their plants radiologically cleaner than pre-1945 technologies, which are in turn didn't radiologically polute the atmosphere as much as nuclear testing did. In pseudo-mathematical code, it would look something like this:

nuclear power plants > pre-nuclear testing power > post nuclear testing ambient environment

Where ">" means "rdiologically cleaner than"

When you look at it that way, it really causes one to wonder why anybody would risk flying around gaseous radioactives.

Tony said...

Raymond:

""Perception" carries an implication of inaccuracy, ignorance, superstition, or all three. I don't think it's particularly fair or useful to lump rational risk management in with such a label."

I certainly agree with that, as far as it goes, but that just plays in Joe's ballpark, by conceding that its a purely semantic issue. While I, as a software designer, would be the last person to claim that semantics are trivial, I think that Joe's attempt to make semantics the issue is fundamentally fallacious.

It's not a semantic issue for me. It's an issue of what we know about radiological contamination and the likelihood of a certain application leading to serious contamination. If you make enough of gaseous core nuclear rocket vehicles, and fly them regularly enough, the probability is close to 1.0 that at least one, and possibly more, will be lost in powered flight. And a loss in powere flight will cause a serious contamination event. I don't think it's an exageration that such an event could be as serious as Chernobyl.

One can't make semantic distinctions about that.

Raymond said...

It's not a semantic issue for me, either - that's why I put in the rest of it. I'm just bothered by the semantics.

Thucydides said...

In flight failure of a lightcraft does not involve the release of radioactivity, burning rocket fuel or even massive pieces of rocket (since the lightcraft is, by definition, lightweight as well as powered by light).

Since the laser battery to launch the lightcraft will be modular, failure of a laser unit will not be catastrophic either, the craft may continue with a longer burn using the rest of the lasers or abort to a suborbital trajectory and landing downrange.

Much of the advantage of a lightcraft lies in the fact that you do not have to haul massive amounts of fuel or remass with you, so while the absolute amount of payload might be small, the payload fraction will be rather large. Imagine launching the Apollo CM without needing a Saturn 1 or Saturn V launch vehicle and you get the idea.

As for weaponizing the laser, the Apollo moon rockets were direct developments of ballistic missile technology, so it works both ways.

Scott said...

Ok, a little bit of admission here: I served on the USS Ohio and USS Kentucky. That's why I have to be careful with some of my citations. Gotta stay under the rules of the NDA.

I know nuke power is potentially dangerous (hello, K19), but the layperson *doesn't* understand radioactivity. period. Tony, you do, because you worked around radhealth issues on the Long Beach (I assume), and then got the thankless job of dealing with them for the hospital.

If the layperson understood radioactivity, they wouldn't go anywhere near the beach, and they'd require lead shielding on airplanes. Both of those expose people to more radiation than living downwind of TMI *at the fenceline* when the release happened. For the record, total measured radiation at the TMI fence was 100mrem and dissipating, roughly 1/5 an average annual exposure in the area. That's been FOIA'd and was NEVER classified to begin with. It's also been the subject of quite a bit of scientific study.

Tony said...

Scott:

" Tony, you do, because you worked around radhealth issues on the Long Beach (I assume), and then got the thankless job of dealing with them for the hospital."

I was only a member of the Marine Detachment on the Long Beach. But we weren't isolated from the Engineering Department guys, and we had direct concerns with nuclear safety on the weapons end of things. (Marine Detachments afloat, before they were discontinued, were primarily responsible for nuclear weapons security on the surface ships they were attached to.)

Also, my hospital safety management experience with radiological issues was in the area of hygiene more than anything else. We didn't get directly involved with the handling of nuclear medcines or the active elements in radiation treatment machines. We were concerned with preventing releases into the environment in dirty linen and trash. And, oh yeah, one time the nuclear medicine contractor's delivery guy came in the facility "hot", and set off the rad alarm on the loading dock. That was a fun afternoon...

Brian said...

I think 1 billion dollars is excessive cost for 20 people to Mars. You are assuming we do things the NASA way and not the right way. Colonies would be done the right way, because they would be done by private enterprise. The government did not colonize North America, and I do not expect it to colonize Mars either.

First of all, it would be not 1000 tonnes. The Orion spacecraft would carry 4 people. Its mass, with capsule and service module (rocket), is 21,250 kg. Multiply that by 5 to get to 20 people, for 106,250 kg or 106.5 metric tonnes. Someone might claim that the Orion is small for people to live for a long mission, but submarines are equally close quarters, and we submariners (I was on the USS Florida (SSBN-728)) live in such tight spaces for about 3 months at a time.

Also, you would only carry the fuel to go one way; return fuel would be generated on Mars.

The numbers get better if you use a superior form of propulsion like nuclear thermal.

--Brian

Geoffrey S H said...

"The government did not colonize North America"

WHOA

Given that I've been spending 3 months at Uni on the colonisation of America, I would say that it was sometimes the government, sometimes private companies that colonised America. For north America at least, it was the state that gae the protection and allowed settlers further inland, but also which regulated commerce, and gave grants to states thart attracted the most settlers.
Both company and state colonised America.

Sorry, had to clear that up. A good text on the subject is "The Atlantic World: Europeans, Africans, Indians and their shared hisotye, 1400-1900. Thomas Benjamen." It dispels many myths about colonisation too.

That said, you have an excellent point about private enterprise. The only problem being- could you get a profit out of a colony and justify the private sector's involvment. Unforetunetly, that seems unlikely, but I would hope you are right!

Rick said...

Good points about government and colonization! And 'public-private partnerships' are nothing new; google the Casa de Contratacion.

On Mars mission architecture, the Orion capsule, less the service module, is 9 tons less change, so 2.25 tons/person for the basic hab. Listed endurance (per Wikipedia) is 210 days, just about the length of a 'fast' Mars round trip on a 90 day orbit with a 30 day stay. But to me it looks awfully cramped - habitable volume is just 9 m3, and 210 days is a long time.

My figure gives 10 tons/person for the full gross payload, the hab plus whatever equipment you take along.

The Orion service module is basically an OMS good for 1.6 km/s, not a deep space drive bus. Also you will need a Mars ascent stage plus final descent burn, a good 5 km/s, and it has to be chemfuel.

Nuke thermal, IMHO, falls between stools. Specific impulse is 2-3x chemfuel, not enough for fast orbits, so I assumed some form of electric drive, which is pretty heavy. In all, I assumed departure mass of 5x gross payload.

Extracting fuel on Mars has two problems. First you need to develop another whole new tech, and send the apparatus along, and second, instead of lifting just the landing party and soil samples from Mars, you now have to lift a couple of hundred tons of propellant.

I would send return propellant and heavy equipment aboard a robotic cargo ship. Rendezvous on orbit is something we already know how to do.

As for the cost of the thing. Private industry could probably do it cheaper than a public effort, but by an order of magnitude? Doubtful.

By way of a benchmark, the C-17 costs $191 million for an empty weight of 128 tons, about $1.5 million/ton, compared to ~$1 million/ton for big civil jetliners. That's a 50 percent differential, and the C-17 arguably has requirements the civil planes don't, like corkscrewing down onto an unimproved airstrip to evade ground fire.

But the real bottom line is that private capital has no significant interest in going to Mars. It would take McGuffinite to change that, and at this point McGuffinite is sheer speculation.

Tony said...

Brian:

"You are assuming we do things the NASA way and not the right way."

Wait just a minute. NASA has its issues, many of them caused by conflicting and competing ideologies, both within the organization and within the Congress that appropriates the money. But if it did things in a more pragmatic way -- say like the Russians do, most of the time-- it would probably only halve the cost, at best. And it would still be tens of billions of dollars to Mars, because we do have to develop and qualify a new heavy lifter, new crew vehicles, new transit and surface habs, etc.

"Someone might claim that the Orion is small for people to live for a long mission, but submarines are equally close quarters, and we submariners (I was on the USS Florida (SSBN-728)) live in such tight spaces for about 3 months at a time."

Sorry, but I have to call BS on this one. The berthing spaces on a sub may be that tight, but a submariner also has his work station, the mess deck, the head, the laundry space, his budy's workspace, a (relatively) wide spot in the passageway, the off-watch spades game on top of the storeroom hatch...

(Yeah...imagine playing spades in microgravity; I might not go just for that.)

Scott said...

The usual claim for an Ohio-class' habitable space is about 3000 sqft. This does not include the engineroom, but does include passageways, heads, and possibly the tops of machinery that you can park yourself on or use as a poker table, etc.

Now, start with a crew of 180ish all sharing that 3000sqft. I'll approximate that to 10-foot ceilings, so that's 30,000cuft or 850m^3. What makes that volume survivable is the fact that only a third of the crew is 'living' in it at any one time. One third is working, and the last third is asleep. This gets the per-person volume down to between 7 and 14m^3, depending on how large your watchstations are. Most of them are roughly 2m^3 per person, so (850-120)/60 = 12m^3 per person.

I would not use any number less than 10^3 per person for long-term habitation (attack submarines are significantly smaller than Ohio-class).

Tony said...

Re: Scott

You left out the mess deck, the laundry space, the engine rooms (which are work spaces), offices (also workspaces), parts of the missile compartment not used for berthing (workspace plus enough space to actually jog), and other miscellaneous spaces not considered "habitable". Yeah, it's close aboard ship, and even closer aboard a submarine, but nothing like current spacecraft designs. It's okay, you don't have to fight it.

Jim Baerg said...

Rick: "Nuke thermal, IMHO, falls between stools. Specific impulse is 2-3x chemfuel, not enough for fast orbits, so I assumed some form of electric drive, which is pretty heavy."

So you use Nuke thermal to cut the amount of propellant needed (& so cut costs) rather than cut the trip time by very much.

"Extracting fuel on Mars has two problems. First you need to develop another whole new tech,"

I thought Zubrin was pretty convincing on the claim that it is mostly old tech & easily testable on earth to the extent that it is new.

"and send the apparatus along, and second, instead of lifting just the landing party and soil samples from Mars, you now have to lift a couple of hundred tons of propellant."

What? Where is the extra propellant requirement coming from?

Rick said...

It is about 18 months round trip to Mars on a slow orbit, adding to the life support requirement. You need a spin hab or the crew will be debilitated.

In any case, if you're taking a slow orbit, developing a new drive rated for human missions would surely cost more than boosting a few more fuel tanks to LEO.

I can't evaluate Zubrin's technical assertions, but on general principles I grab my wallet when he talks. He brushes off an awful lot of devils in the details.

Your robotic precursor missions now have a major additional task, assessing possible landing sites to make sure the ice is actually accessible at those locations, and make sure your technology works under Mars conditions.

The mass of propellant is to get you not just off Mars but back to Earth. According to the handy table at Atomic Rockets, Mars surface to LMO is 4.1 km/s, plus 2.3 km/s from LMO to minimum Earth transfer orbit.

That burn has to send the whole long duration hab back to Earth, so a substantial amount of propellant will be involved. And it all has to first be lifted 4.1 km/s to LMO.

Ignoring details like tankage and such, if hab mass is 100 tons, you need 67 tons of propellant to send it back to Earth, and another 100 tons of Mars lift propellant to get that propellant into orbit.

This is awfully demanding! I admit that my preferred architecture is even more demanding, because it involves development of a human rated electric drive delivering a few hundred watts per kg. But it takes that risk before departure, not on Mars.

Tony said...

Re: Rick

Zubrin doesn't rely on water ice for fuel. His plan is to send along a tank of liquid hydrogen, then use the CO2 in the Martian atmosphere to make methane and liquid oxygen. Jim is right that this approach relies on decades old standard industrial techniques. But Rick is correct that Zubrin handwaves away the difficulties of operating these techniques remotely at interplanetary distances, not to mention the difficulty of maintaining several tons of liquid hydrogen over a period of years that it would take to get it to Mars and then use it up making methane.

Also, there's no fundamental reason that nuclear thermal technology could not be used to shorten interplanetary transit times. After all, an NTR will run as long as you keep the dampers out and feed it reaction mass. Nuclear electric looks more likely, due to both technical and political reasons, but nuclear thermal is not fundamentally less powerful.

Rick said...

Zubrin's proposal does neatly sidestep the problem of prospecting for and drilling a well, and the underlying process is certainly well established tech. Doing it on Mars, with reliability and robustness ... challenging.

On nuke thermal, the handy drive table at Atomic Rockets credits solid core NTR, hydrogen propellant, with an exhaust velocity around 10 km/s = ~1000 seconds Isp. Methane propellant reduces this by about a third. This is a fundmental limit set by core temperature.

Calculating fast orbits is above my math pay grade, and there don't seem to be any handy online tools. But as best as I can tell by sketching, interpolation, and sheer guesswork, Mars in 3 months (one way) requires a delta v of 40-50 km/s, way beyond the reach of solid core NTR.

Liquid core NTR is good for about 20 km/s (hydrogen), but adds a major new design challenge, the liquid core. This strikes me as more difficult than getting, say, 300 watts/kg out of an electric drive.

Tony said...

Re: Rick

I think you're presuming size constraints that I'm not. If you increase the mass ratio, you increase the delta-v. Of course there are certain limits of practicality -- if you go too far in increasing mass ratio, you're adding kilotons of fuel for each extra kps of delta-v. Still, if reaction mass is a relatively cheap commodity -- and it could be, in a couple of hundred years -- there might be some use for fast NTR ships.

Raymond said...

It's not like NTR engines can burn forever - the core will experience substantial corrosion. NERVA's tests indicated that at full power, the core's useful life would be measured in hours.

There's also an asymptotic limit to the payload fraction, simply due to tankage requirements. Off the cuff, I'd say a mass ratio of about 5 (propellant fraction of 0.8) would be the practical limit, based on current tank tech and reasonable size (ie can be lifted into orbit). This would give us about 16 km/s from an NTR with 10 km/s exhaust velocity. Nothing to sneeze at, but not enough for a fast orbit to Mars in the same league as nuke-electric should be.

Tony said...

Raymond:

Hours of full power service life could equate to several round trips. Or, if you use the engine bimodally, maybe one round trip, but you get ship's service power in the bargain.

It also depends a lot on your assumptions about infrastructure. Higher delta-v in general means you'll get there faster, maybe by a little, maybe by a lot. Certainly by a lot if you assume a gas station at the other end. (That's outside the near-term, but not unreasonably outside the plausible mid-term.

Thucydides said...

NERVA (or modern variations like "Timberwind") may have advantages over chemfuel, but are hopelessly outclassed by plasma drives like VASMIR. All other things being equal, NTR is going to be a niche product, somewhat like steam engines for cars or trains today.

There is one place where NTR would be useful, transporting bulk water or other materials from NEO's, asteroids and ice moons. The assumption here is that using straight water as remass through the reactor would save a large amount of mass by eliminating the need (and machinery) for LH2. With an ISP limited to whatever a steam rocket provides (probably an ISP @ 400, similar to a hydrogen/oxygen rocket) you won't be setting many speed records, but unmanned cargo "tankers" and "container ships" could be possible using these means. This is also an improvement over shooting ISO shipping containers on minimum energy trajectories via mass driver in terms of flexibility and scheduling, but a lot of cost analysis will be needed to determine which approach works best.

WRT Zubrin, I still like his work since there is less Handwavium involved than many other plans (like the President George H.W. Bush plan, or even Das Mars Projekt). The other thing to consider is Mars Direct does not go unless the robotic fuel processor has already landed, checked out and produced the fuel for the return trip, which might be frustrating for the crew waiting for a launch window on Earth, but much better than getting there and finding yourself stranded. Of course you can do Mars "sort of direct" and send one or more fuel tankers full of liquid Methane along; so long as each individual spacecraft is fairly light aerobraking is possible.

Mars Direct is so '90's; today's iteration might include robot tankers and fuel processors sent ahead of a VASMIR drive crew ship, which arrives only 39 days after breaking orbit. We still need someone to write the cheque, though.

Rick said...

In fact you can assume a gas station at the other end, or at least a tanker truck, sent on a slow orbit. The slow truck can also carry the Mars landing suite. The only part of the mission that needs to go fast is the crew and their hab.

The key human travel time constraint, IMHO, is that we know from experience that much more than 6 months of microgravity is debilitating, so you need a spin hab unless you take fast orbits. And more than a year or so in deep space, with only very limited shielding, takes a big bite out of career radiation exposure limits.

Tony said...

Re: NTR vs NER

The superiority of NER like VASIMR presupposes that a sufficiently powerful electrical generation system can be supplied for proulsion power. If that can't be achieved -- I think it can be, but if it can't... -- we may be left with NTR as the default solution.

Raymond said...

Tony:

"Hours of full power service life could equate to several round trips. Or, if you use the engine bimodally, maybe one round trip, but you get ship's service power in the bargain."

Depends on whether we're talking about two hours or twenty. Bear in mind I'm not inherently arguing against NTR - I suspect even if/when we develop nuclear-electric propulsion, nuclear-thermal will be cheaper, and thus have a place.

Bimodal designs usually involve dropping the reactor power levels to a hundredth of maximum, and the core lifetime doesn't scale linearly. IOW, a bimodal setup probably won't cost you that much in terms of overall service life.

Thucydides:

NTR has two problems with water: specific impulse lower than LH2/LOX combustion, and greatly increased core corrosion. For the cost of a smaller nuclear reactor (and one not built to the tolerances of a rocket engine) and some time, you'd be better off cracking the water into LH2 and LOX and just burning it.

And dear god, the core corrosion. At the temperature of a nuclear rocket, at least some of the water will dissociate into H2 and O2. Graphite burns in oxygen. Oxygen is more reactive than hydrogen with the materials an NTR core will likely be made from. This is a Bad Combination.

You could still crack the water and dump the oxygen, though, only using the hydrogen for propulsion.

Re: Zubrin

The Sabatier reaction (the process in question) is also potentially useful for scrubbing CO2 in life support systems. A full test in a Martian environment would be a good test for both life support and fuel production. A robotic test mission, with a small space-rated nuclear reactor, sounds perfect as a next step.

Tony said...

Re: NTR and reaction mass composition

It's an issue of where and how you want to expend energy. H2 has its inbuilt advantages, but it takes energy to process and leads to parasitic mass on the rocket, thanks to storage volume and temperature requirements. H20, on the other hand, while more corrosive, can be stored in more compact tankage, with less need for refrigeration, and is only in need of refinement for purification purposes. If you can get a nuclear steam rocket up to LOX/Kerosene Isp levels -- aggressive, but not too aggressive -- it's possible that it would make economic sense where max efficiency eleiptical transfer orbits are acceptable and energy at the gas station is hard to come by, like ice mining in the asteroid belt and beyond.

Raymond said...

This is probably in the category of Best Decided By Experiment (So Get On With It Already, NASA).

Anonymous said...

Energy, energy, energy. It all comes down to energy. Space travel requires large amounts of energy. Chemical bonds aren't going to do it. You need nuclear. Until we go nuclear, space travel will remain expensive, because what we are using has too low an energy density (it's the same reason electrics cars will always be expensive with poor performance).

With nuclear energy, space travel gets cheap. Really cheap. Ferrying people to orbit? Space fountains. Ferrying cargo? a 10-megaton nuclear cannon. That makes putting an orion-type vessel in orbit trivial. And one of those gets you to Mars in about 6 days.

Milo said...

...What? What? No, current nuclear power technology does not make generating enough energy for space travel "trivial" - building the nuclear reactor itself (a large, heavy piece of equipment with stringent safety requirements) is decidedly nontrivial, and it still produces only a finite amount of energy, especially under space-based mass limits. Trying to propel your ship by repeatedly nuking yourself is definitely non-trivial.

Nor have I before seen any claim of fission-based technology that could get you to Mars in six days. That would require a delta-vee of 600 km/s at accelerations measured in decigees. That's hundreds of megawatts per ton of ship. 2 megawatts per ton is optimistic for a fission reactor. Even near-term fusion, if we figure it out, wouldn't be that good.

Try Earth to Mars in a month or two, rather than six days. That's what VASIMR proponents tend to suggest.

Tony said...

Re: Milo

I think our friend interprets "nuclear" as "fusion, in its most optimistic form, as imagined between about 1965 and 1995".

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