Comments on Rocketpunk Manifesto: Space and Heresy

SA Phil: "IS that a step towards the Rock...

2011-08-01T08:52:13.620-07:00
SA Phil:

"IS that a step towards the Rocketpunk idea of large computer rooms then?

Specialized large computers with low component densities and redundant tasks."

No, microcomputers are okay. You just can't have the high component density models of the last 20 years. Also, you have to remember to save your files on a regular basis and have multiple redundant systems for critical tasks.

(SA Phil) IS that a step towards the Rocketpunk i...

2011-07-29T20:17:46.666-07:00
(SA Phil)

IS that a step towards the Rocketpunk idea of large computer rooms then?

Specialized large computers with low component densities and redundant tasks.

... random and unexpected shutdowns caused by c...

2011-07-29T16:05:27.919-07:00
... random and unexpected shutdowns caused by cosmic ray strikes. I wish that were a joke, but it's not.

+10

SA Phil: "I had to laugh about the refere...

2011-07-29T09:20:46.374-07:00
SA Phil:

"I had to laugh about the reference to Rickover and the subsequent dismissal as hero worship...

Still he and his crew put together one hell of an engineering legacy."

He had a good organization because he was an good engineer with an effective (albeit extremely abrasive and unforgiving) management approach. Beyond his technical skill as an engineer, he had a good intuitive sense of what would work and what wouldn't. Powerplant designs coming out of his organization, even when they employed innovative solutions in the details, were as conservative and simple as they could be.

"The 386 comment made me laugh. Maybe Nasa needs a better computer budget. Although you can do a lot with a 386, you would be better off using a Power PC based system since there is far more development money poured into control systems using those.

They probably used it as an off the shelf piece which had had hardening work already done for the shuttle or something.

The 386 is used because it has a low enough component density to minimixe -- though not entirely eliminate -- random and unexpected shutdowns caused by cosmic ray strikes. I wish that were a joke, but it's not.

(SA Phil) I had to laugh about the reference to R...

2011-07-25T15:26:28.513-07:00
(SA Phil)

I had to laugh about the reference to Rickover and the subsequent dismissal as hero worship.

My Dad worked for Rickover at Naval Reactors - and my Mom never had anything nice to say about the Admiral.

Egotistical and Elitist to the extreme was what I took from her description.

Still he and his crew put together one hell of an engineering legacy.

===============

The 386 comment made me laugh. Maybe Nasa needs a better computer budget. Although you can do a lot with a 386, you would be better off using a Power PC based system since there is far more development money poured into control systems using those.

They probably used it as an off the shelf piece which had had hardening work already done for the shuttle or something.

(SA Phil) RE: Energy on a space colony The initi...

2011-07-25T14:33:06.660-07:00
(SA Phil)

RE: Energy on a space colony

The initial Photovoltaic solution will probably be the lowest mass one possible, not the one most efficient area-wise. (in operation)

Since if you are one of a tiny colonial population you will have a premium on weight and an abundance of land area.

So it will probably be a thin film semiconductor deposited on a polymer that is rolled up and shipped with the colonists.

Once they arrive it will be unrolled and hooked up. There wont be any racks or glass or anything of that nature. There probably wont even be electrical shock protection.

This technology already exists - although it is of more limted use on Earth since you have to protect the thin film PV material from water by encapsulating it in even more polymers. Not a problem on most colonies in this Solar System.

------
You wont be making your own solar panels in space right away since it requires large amounts of energy - which you won't have if you need the solar panels for energy.

-----

Concentrating sunlight with mirrors might happen to an extent with PV - but conversion efficiency drops off with temperature, so that will not go beyond a certain point. Since you will "lose" much of what what you "gain"

I think that the purpose of the colony/outpost is ...

2011-07-12T19:11:35.383-07:00
I think that the purpose of the colony/outpost is the most important concideration when deciding whether to place it on the surface or in orbit; some tasks are better suited on the ground and others in space. This isn't an either/or question (from my perspective), but rather one of best usage of the locale for the purpose given.

Ferrell

For the same amount of technical and economic cons...

2011-07-10T12:56:25.085-07:00
For the same amount of technical and economic constraints, you have 3X the amount of "input" with space based solar vs ground based solar on Earth. Anyone in orbit around any planet of body in the solar system will have a similar advantage (sometimes a huge advantage compared to small, rapidly rotating bodies), so the answer is still the same: advantage to space.

Since it will be relatively easy to scale up to arbitrary sizes in space compared to planetary bodies, the advantage is still to the space based systems.

Since the initial question was about the advantages of a space based colony vs a planetary based colony, it can be assumed that the economic and technical aspects WRT space access and high tech equipment is the same, for the amount of effort and energy needed to establish a ground based colony and build a solar array, you will have a much more efficient array in space, and better access to energy.

For the best of both worlds, a ground colony would be best served by having the power generation systems in orbit and beaming power to the ground.

Re; Thucydides With all due respect, you seem to ...

2011-07-09T18:36:29.559-07:00
Re; Thucydides

With all due respect, you seem to be working overtime to miss the point. It doesn't matter how much sunlight you have, or how constant it is. If your ability to utilize it is limited by technological and economic constraints, then it is limited by those constraints. And everything one does in this life is limited by technological and economic constraints.

Thinking that energy in space is absolutely mo...

2011-07-09T10:09:23.701-07:00
Thinking that energy in space is absolutely more accessible is thinking at the level of toy problems handed out by physice professors, not at the level of real world engineering systems.

In the specific instance of solar energy, the fact that it is available 24/7 in free space gives you a considerable advantage over ground based systems. Really the only true comparison would be nuclear systems that can also run 24/7.

I would be quite wiling to say that this holds true anywhere in the solar system; a solar array on the surface of Mars has to deal with weather, gravity and day/night cycles that one in Martian orbit does not have to. Farther out, free space systems can scale in ways that planet based ones do not; a mirror array orbiting Uranus can be arbitrarily large, but one on Ariel will be limited in size as well as by the local gravity and day/night cycles.

For various reasons I actually think that the "solar" economy will be limited to the orbit of Mars, while any civilization settling around Jupiter will exploit the Jovian magnetosphere and deep space civilizations will use fusion energy fueled by 3He mined from the atmosphere of Uranus, but this is more of a personal evaluation and makes for an interesting setting for speculations.

I expect helium to separate out from oxygen be...

2011-07-09T08:35:55.313-07:00
I expect helium to separate out from oxygen because I've seen stories about how the thinners in contact cement will evaporate out and build up at floor level until they hit the pilot lights and then BOOM!

CJ, in such situtions, the flammable vapors were never mixed with the air to start with. There were macroscopic parcels of gas with different densities. You didn't have diffusive separation of gases well-mixed at the molecular level. Indeed, that situation can occur because diffusive mixing is also slow!

Consider that xenon gas is more than four times denser than air. Yet, the relative concentration of Xe in the dry air is constant below about 80 km (the homopause). The gravitational separation of gases at the molecular level is extremely slow, and the separate is entirely negated by even minimal mixing.

Hmm … We seem to be going in two different directi...

2011-07-08T16:47:47.637-07:00
Hmm … We seem to be going in two different directions with this thread. Is it about plausible futures or fictional futures? One vision is obviously more constrained than the other.

However, in either version of a grand space future, we have to think about economic motivations. Why are people traveling about the solar system in large numbers? Even assuming many inhabited bodies, does trade in actual goods and services justify very many flights? How often will the easy and inexpensive transfer of information be the more economical choice?

Re: Thucydides I agree that a balance must be str...

2011-07-07T23:57:53.150-07:00
Re: Thucydides

I agree that a balance must be struck between complexity and attainability. But within that balance is also a tradeoff between expense and efficiency. This means that energy is not automatically and necessarily cheaper in free space for any given amount of material and labor investment. Thinking that energy in space is absolutely more accessible is thinking at the level of toy problems handed out by physice professors, not at the level of real world engineering systems.

Tony I am going from the general principles here;...

2011-07-07T19:53:45.305-07:00
Tony

I am going from the general principles here; people with relatively modest technical capabilities can build mechanical items of various sorts, including heat engines. While it is true an alpha stirling engine built out of pop cans will hardly be efficient, it is still proof of principle that even people with limited access to materials can build a working engine.

Building solid state devices is simply orders of magnitude beyond the resources and abilities of the vast majority of people. (If you do have these abilities, then you will be in very great demand indeed).

And even highly complex devices have been built by model engineers; I have seen a Napier Deltic engine done in scale, which is perhaps the most complex engine ever put into production. http://craftsmanshipmuseum.com/tomlinson.htm

So the argument isn't really what is better, but what is possible to do. Obviously the end state will be somewhere in the middle, but to find the middle we need to look at each end of the bell curve as well.

=Milo= Tony: "The more efficient and u...

2011-07-07T09:49:44.990-07:00
=Milo=

Tony:

"The more efficient and useful a power source gets, the more complex and rare its key compnents are."

I think this is not so much a physical rule as it is an economic one - if a power source is both weaker and more expensive than available alternatives, then people would never use it, and so would come to think of that technology as a curiosity rather than a power source. The only power sources that are actually in use are the ones that are optimal in some manner (anything cheaper than it is also weaker, anything stronger than it is also more expensive).

This applies to all technology, by the way, not just power sources.

Milo- re: photovoltaics, mirrors, & aluminized...

2011-07-07T08:51:31.556-07:00
Milo- re: photovoltaics, mirrors, & aluminized plastic.

Whether plastic will be expensive depends on what bodies you are getting your raw materials from. If they are carbonaceous chondrite asteroids, there will be plenty of raw material for making plastic.

If you are digging up rock from the moon or mercury, then plastic will be hard to get, but aluminum foil for mirrors will be cheaper than photocells per m^2.

Re: Brian I'll only say that someone who beli...

2011-07-06T23:00:48.154-07:00
Re: Brian

I'll only say that someone who believes that NASA actually makes the rockets they use is beyond reason.

Re: Thucydides Energy is neither cheap or reliabl...

2011-07-06T21:26:24.027-07:00
Re: Thucydides

Energy is neither cheap or reliable if you're using Stirling engines, no matter how much sunlight you focus on them. In fact, you can't focus much sunlight on any given engine because it's got serious thermal and mechanical limitations. That's why they so quickly and easily shifted from reciprocating engines to turbines in the 20th Century.

But efficient turbines are complex, high precision machinery. You just don't ring up the corner shoppe to get delivery of however many you desire.

This, BTW, is an engineering principle that applies anywhere, anytime. The more efficient and useful a power source gets, the more complex and rare its key compnents are. TANSTAAFL.

Re: "photovoltaic" and "solar" cells, perhaps you need to read the first paragraph here:

http://en.wikipedia.org/wiki/Photovoltaic_cell

also, tony, "current or foreseeable material...

2011-07-06T20:59:33.131-07:00
also, tony,

"current or foreseeable materials technology is not up to giving you a workable reusable vehicle with a payload."

I will concede that NASA of 2011 is probably incapable of designing and implementing an SSTO rocketplane.

The mantle of NASA in 1969 -- the awesome trailblazer who leaves everybody else in their dust -- has been taken up by SpaceX et al.

How long, and how many people, did it take for NASA to accomplish a test flight/firing of Ares I? How long, and how many people, did it take SpaceX to get their rocket all the way into orbit?

SpaceX in 2011 = NASA of 1969.

SpaceX is flying the US Flag...Falcon 9 is an American accomplishment. but the flag happens to be flown by a private sector organization. That's how it is going to be in the future.

The times they are a changin'...

--Brian

Tony, sorry to bother you again! But, you are stil...

2011-07-06T20:32:34.211-07:00
Tony, sorry to bother you again! But, you are still not reading the Star Trek and Firefly references correctly! :-O Again, the point is, "a Star Trek future" is one in which billions of people live on Mars, various moons of gas giants, Venus, and planets orbiting other stars. It doesn't mean you have warp drive or anything like that. Although, don't forget that Einstein allows your starship to travel at 0.99999999999999999 * c. Like SSTO, it may be difficult from an engineering standpoint, but it is not impossible; it does not violate the laws of physics.

Now, if we rely on NASA to somehow create that ST/SW/BSG/FF future, using government employees as the populations of the planets etc., that is never going to happen, any more than the colonists at Jamestown were all enlisted in His Majesty's Royal Navy. The people who populate planets on Star Trek are not all (or even mostly) Starfleet members either.

What NASA can do, and should do, is advise, support, and accelerate the commercial exploitation of space. Sometimes that will mean building infrastructure intended to be used by the private sector, sometimes that will mean doing research, sometimes it will mean sending probes to unexplored places, sometimes it will mean doing emergency rescue. Those are all valid functions of government (imho).

But the people who do routine functions at sea, who colonize places, etc., are in the private sector, not government employees of any kind (not NASA government service employees, not astronauts).

I don't know how we got to the point that we think everything that is done in space should be done by NASA or the government. But it didn't happen that way in the frontiers on Earth, nor should we expect it to be done that way in the Final Frontier.

I don't look to the government for a Vision for colonizing and settling space any more than I look to them for a Vision on how to transport people from New York to London on a routine basis.

If you look to the government to settle space, the most you can hope for is research stations, like we have at the South Pole. Colonization and settlement is something that private individuals and groups do! Ad Astra. :)

--Brian

Although I never specified heat engines as the mea...

2011-07-06T19:57:39.363-07:00
Although I never specified heat engines as the means of generating energy in space, in principle I think this is actually a good idea.

Consider that I have an design for an alpha Stirling engine from Make magazine which I can build with my ten year old son. It uses Coke cans as the piston/displacers, coffee cans as the cylinders and various assorted pieces of tubing, wire coat hangers and scrap wood for the rest. Anything not in my garage is easily available at Canadian Tire or Wal Mart.

There is no way that I could possibly make photovoltaic cells, optical rectenna or devices using quantum dots in my garage (although weirdly it is possible to make a Farnsworth–Hirsch Fusor in a garage with slightly above average building skills; high school students can do this).

For a space civilization limited by lift constraints, repurposing items or building relatively simple devices may be more cost effective than importing more efficient devices from Earth or attempting to build/import a fab to build integrated circuits and photovoltaic cells. Space civilization might be shiny and bright on the outside, but resemble the interior of a tramp steamer on the inside while things get organized.

Anyway, as Jim Baerg said, concentrating light on photovoltaics is also a valid course of action, and minimizes the need for expensive and imported solar cells.

Finally, the availability of energy is pretty much the equivalent of wealth. Societies with access to cheap and readily available energy are far richer than societies that have limited access to energy. I see no real reason to assume this general rule will not apply in space as well.

I expect helium to separate out from oxygen becaus...

2011-07-06T14:48:49.598-07:00
I expect helium to separate out from oxygen because I've seen stories about how the thinners in contact cement will evaporate out and build up at floor level until they hit the pilot lights and then BOOM! And then there are stories about staying low to the ground in a fire because all the smoke rises. It would seem to me that a gas that is an eighth the density of oxygen would percolate out. Note that nitrogen is very close to the same density as oxygen and thus mixes well.

I'm not saying that helium must stratify out, I'm just saying that it isn't intuitive for it not to.

Byron: "I said that we're doubling th...

2011-07-06T12:03:02.469-07:00
Byron:

"I said that we're doubling the launch budget, not the launch rate. At some point, real mass production will occur. What if it's cheaper to make 60 mass-produced lanchers then 30 current designs?"

I understood what you said. But twice the budjet is only going to buy maybe a little bit better than twice the launch rate. In any launch campaign, the cost is in organizational work, not in hardware. Yes, a higher launch rate would allow for some sharing of resources, but not as much as people think. Most rocket models have to have dedicated pads/assembly-buildings/launch-ontrol-centers, and those pads/assembly-buildings/launch-ontrol-centers are often run at near maximum capacity by their operators. More rockets = more pads/assembly-buildings/launch-ontrol-centers = more pads/assembly-buildings/launch-ontrol-centers personnel.

"Maybe it would take tripling instead of doubling, but at some point, the cost would fall dramatically."

Let's look at a real high launch rate rocket, the R-7. In the last 54 years, 1740 R-7s have been flown, at an average rate of a little bit more than 32 per year. Most of those launches were under the command economy conditions of the Cold War Soviet Union. Yet today, with the development costs completely absorbed, and hardware coming at true unit prices, the commercial market only buys about 12 per year. (And it's important to remember that NASA is transitioning to a commercial customer model for LEO operations.) The last big post-Soviet year was all the way back in 1992, with 32 launches, almost all ordered and paid for by the Soviet government and flown out of sheer inertia while the post-Soviet government was concerned with other things.

In any case, a customer -- even the Russian government -- has to order an R-7 two years prior to the scheduled launch date. They just don't make and stockpile launchers, and wouldn't even at more than twice the launch rate, because R-7 components are made in the same old factories they always were. And those factories once easily supported more than twice the current launch rate.

In the US, the proportion of the rocket industrial base dedicated to NASA launches is maybe 15-20%. If we upped the NASA launch rate of medium lifters to twice or three times the current rate, we would have to proportionally expand the industrial base by expanding current rocket factories or build new ones, training work forces, and making the facility expansions at the Cape that have already been discussed. It might cost more than twice the money to increase the NASA launch rate by two.

As far as heavy lifters are concerned, the industrial base can easily support four Shuttle stack-sized launches in a year, and has in the past supported up to eight. So, given a Shuttle-derived heavy lifter (which seems to be the direction things are headed) it would seem that mo money = mo launches. But wiat just a minute...that heavy lifter hasn't been developed yet, so mo money actually doesn't mean much with heavy lift until we actually have a flight-qualified rocket.

I said that we're doubling the launch budget, ...

2011-07-06T11:08:09.358-07:00
I said that we're doubling the launch budget, not the launch rate. At some point, real mass production will occur. What if it's cheaper to make 60 mass-produced lanchers then 30 current designs?
Maybe it would take tripling instead of doubling, but at some point, the cost would fall dramatically.

WRT chemfuel rocketry costs and economies of scale...

2011-07-06T11:04:04.174-07:00
WRT chemfuel rocketry costs and economies of scale, I think the savings are only going to be marginal, because 30 or 40 launches a year rather than fifteen or so still puts rockets in the specialty item category. We have to remember that a Delta IV or Falcon 9 rocket is not a serial production item, but a design to from which individual examples are built for specific missions. doubling or even trippling the launch rate is not very likely to change that.

Comments on Rocketpunk Manifesto: Space and Heresy

SA Phil: "IS that a step towards the Rock...

(SA Phil) IS that a step towards the Rocketpunk i...

... random and unexpected shutdowns caused by c...

SA Phil: "I had to laugh about the refere...

(SA Phil) I had to laugh about the reference to R...

(SA Phil) RE: Energy on a space colony The initi...

I think that the purpose of the colony/outpost is ...

For the same amount of technical and economic cons...

Re; Thucydides With all due respect, you seem to ...

Thinking that energy in space is absolutely mo...

I expect helium to separate out from oxygen be...

Hmm … We seem to be going in two different directi...

Re: Thucydides I agree that a balance must be str...

Tony I am going from the general principles here;...

=Milo= Tony: "The more efficient and u...

Milo- re: photovoltaics, mirrors, & aluminized...

Re: Brian I'll only say that someone who beli...

Re: Thucydides Energy is neither cheap or reliabl...

also, tony, "current or foreseeable material...

Tony, sorry to bother you again! But, you are stil...

Although I never specified heat engines as the mea...

I expect helium to separate out from oxygen becaus...

Byron: "I said that we're doubling th...

I said that we're doubling the launch budget, ...

WRT chemfuel rocketry costs and economies of scale...