Saturday, May 14, 2011

A Little Blowup


As some of you probably noticed - especially if you tried to post a comment - Blogger had a bit of a blowup a couple of days ago.

Things are reportedly getting back to normal, and any vanished comments are supposed to reappear this weekend. Assuming no further crashes, feel free to use this as another open thread.



A star in Taurus suffered a much bigger blowup in 1054, producing the rightly celebrated Crab Nebula.

210 comments:

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Anonymous said...

When Blogger works right, it's fine; when it has a problem, it annoys to no end.

There were concerns about a star several thousand light-years away that could go supernova in the near future; normally the distance wouldn't be a source of concern, but it seems to be pointed in our general direction. Astronomers don't know whether the eventual gamma ray burst will pass close by, or hit us dead on. Anyone know more about that?

Going back to some earlier topics, I had an idea about a rocket engine that used a coil of copper wire inpregnated with positronium; it was fed into a device like a Hall thruster;the surface of the wire is viporized by an electric arc; the resultant plasma is then crushed by a magnetic field, the x-ray flux destablizes the positronium and the resulting gamma rays heats up the plasma to enormous tempatures and is ejected via magnetic nozzle. You can pump additonal propellents into the plasma stream to increase thrust (at the expense of ISP), or you can route the plasma into a verity of power generators. The positronium would come from a side reaction from a noval fusion reaction that helps power the future civilization in my story setting. My question is: does this sound plausible (given the handwave for the production of positronium), or is there some glaring problem I'm not seeing?

Ferrell

Anonymous said...

The one problem with that drive is that positronium will collapse really fast. The only way you could impregnate it is to fix the electron, but not the positron. This would still make the positronium unstable though, so you would have to handwave a way to stabilise the stuff, and then you would have to handwave a way to impregnate it, and then you start handwaving the whole drive, so you might as well just go with magical tachyon thrusters instead

Anita said...

Would appear the Crab Nebula still has heart burn.

From Science Daily: NASA's Fermi Spots "Superflares" in the Crab Nebula.

www.sciencedaily.com/releases/2011/05/110511165312.htm

Sabersonic said...

Well, might as well take this opportunity to ask these two tech idea questions.

1) Is there a Fusion version of the Nuclear Lightbulb?

2) In a Jet Engine, can plasma perform the combustor fuction on its own (i.e. without jet fuel)?

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Brian said...

Has anybody read Ark by Stephen Baxter? He has a degree in Mathematics from Cambridge, and one in aerospace engineering from Southampton University, so he knows his stuff. But, in this book, the Earth is slowing being covered by the oceans (every last meter of land is going to be covered), so they create a few ships so some people can survive, one of them is a starship.

Now, you would think that with present day technology, in this situation, what they would do is go to the Moon or Mars. But, the characters in the book feel that they don't want to try and keep an artificial environment on one of those two places going for thousands of years (until the waters recede on Earth).

So, instead, they create a warp drive, based on the Albuierre warp drive. We have all heard that it would take more energy than exists in the universe to create a warp bubble with that technique (or whatever), but in the book, Baxter claims you could create a very small warp bubble, barely large enough to hold a neutrino, using only the amount of energy released by the largest nuclear weapon ever detonated.

He claims in the book that, even though the bubble would be small in our universe, it could still have a very large internal volume, in higher dimensions and/or in its own universe, large enough to hold a starship.


They use antimatter to make enough energy for the warp bubble, collected at Jupiter. Supposedly there is a natural particle accelerator there (from the plasma channel between Juptier and Io). They get from Earth to Jupiter using an Orion drive (nuclear weapons propulsion).

So, do any of you guys think that is plausible? Baxter would know better than me, he has a degree in math from Cambridge.

Like I said...if I were him...I would just have had them go to the Moon or Mars. I'm more of a Mars fan, but in this case, the Moon might be best because it is closest, and supposedly they only had 15 years or so to get a colony set up before the world is completely flooded (state of Colorado was the largest bit of land not covered when they launched the spaceship). His characters in the book claim that there is no water on the Moon, but actually, spacecraft have discovered a lot of ice on the Moon, especially near the poles, which he should have known, since he wrote the book in like 2009.


What do you guys think??

Chris said...

Sabersonic:
2) In a Jet Engine, can plasma perform the combustor fuction on its own (i.e. without jet fuel)?

Sort of. A normal jet uses the air it intakes as the reaction mass, and the fuel is just to heat it up. If your fusion plasma is providing all the thrust it's just a fusion torch. If you're pulling fusion plasma for heat, it's the standard Brayton cycle and would work. Off the top of my head, your fusion plant would have to mass less than the jetfuel to be worth it. If you want it for an alternate mode, just realize it'd be less efficient (but multipurpose).

Anonymous said...

Other Anonymous said:"The one problem with that drive is that positronium will collapse really fast."

I thought that positronium was stable; why would it collapse quickly?

"The only way you could impregnate it is to fix the electron, but not the positron. This would still make the positronium unstable though,..."

I have no idea what you are talking about here. Infusing one substance into another is simply mixing the two. Given that positronium is suppose to be stable, it should act like any other element, until you purposely destabilize it.

What I'd like to know is if the copper plasma will absorb most or all of the gamma rays, or if most of the energy will escape? Do I need to tweek the destabilization method, or does it sound plausible? Or should I drop positronium and go with a psudo-atom of a balanced pair of mutually orbiting proton and anti-proton?

Sabersonic: if the plasma can get hot enough to ignite an oxygen/nitrogen fire, then yes, your plasma driven jet engine can work.

Brian: I think he just wanted to work a warp drive into his story.

Ferrell

Jim Baerg said...

Ferrell: "I thought that positronium was stable; why would it collapse quickly?"

Apparently you thought wrong.

From the wikipedia article on positronium:
"Positronium (Ps) is a system consisting of an electron and its anti-particle, a positron, bound together into an "exotic atom". It is unstable. The two particles annihilate each other to produce two gamma ray photons after an average lifetime of 142 ns in vacuum."

Milo said...

Ferrell:

"There were concerns about a star several thousand light-years away that could go supernova in the near future; normally the distance wouldn't be a source of concern, but it seems to be pointed in our general direction. Astronomers don't know whether the eventual gamma ray burst will pass close by, or hit us dead on. Anyone know more about that?"

You are probably talking about WR 104. See also here.

According to this, "Observations suggest significant variation in the jet angle from between 2 and 20 degrees.", which means that if the 30-40 degree value for WR 104's angle is accurate, then we're probably outside its beam path.

Anonymous said...

Ok, positronium is out; so what about the proton/antiproton psudo-atom? Does it last longer than 142 ns before it self-annihilates?

Ferrell

Anonymous said...

Well a quick visit to Wikipedia and a new plan for my compact super rocket; use Hadronic atoms where one of the electrons of the copper atom is replaced by an antiproton. Change the process that generates them into a complicated combined cycle of fission/fusion with the main reaction chain for energy but with the side reaction creating this exotic atom that can be later destabalized inside the bulk of the regular copper through relitively easy means, but not so easy as to risk accidental destabilization.

I think that I can get a 0.01g thrust from this antimatter-boosted rocket drive for several hundred hours; enough for reasonable trip times to planets at least out to Saturn.

I thought that positronium was stable because the last time I read anything about it, the article was about how the dominante atom in the universe, after the decay of protons, would be positronium. My mistake.

Ferrell

Tony said...

Ferrell:

"There were concerns about a star several thousand light-years away that could go supernova in the near future; normally the distance wouldn't be a source of concern, but it seems to be pointed in our general direction. Astronomers don't know whether the eventual gamma ray burst will pass close by, or hit us dead on. Anyone know more about that?"

If you're talking about Eta Carinae, it's possible that when it blows, it will generate a gamma ray burst. But as this image clearly shows, our solar system is significantly off the beam axis. The general gamma ray output may effect spacecraft and any human occupants, but that's about it.

Sabersonic said...

"If your fusion plasma is providing all the thrust it's just a fusion torch. If you're pulling fusion plasma for heat, it's the standard Brayton cycle and would work."-Chris

Actually I was thinking of something a little low in power output, something that would fit on a conventional aircraft design. I'm just wondering if the basic premise is possible since I heard of a Plasma Jet Engine for aircraft on a Sci-Fi show.

"if the plasma can get hot enough to ignite an oxygen/nitrogen fire, then yes, your plasma driven jet engine can work.
"
-Ferrell

How hot would the plasma need to be, even if the compressor design is utilized, and what would be the upper limit of plasma arcs powered by a generator onboard any possible aircraft?

And I'll take it that there are no designs of a fusion equivilent to the Nuclear Lightbulb?

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Sabersonic said...

"If your fusion plasma is providing all the thrust it's just a fusion torch. If you're pulling fusion plasma for heat, it's the standard Brayton cycle and would work."-Chris

Actually I was thinking of something a little low in power output, something that would fit on a conventional aircraft design. I'm just wondering if the basic premise is possible since I heard of a Plasma Jet Engine for aircraft on a Sci-Fi show.

"if the plasma can get hot enough to ignite an oxygen/nitrogen fire, then yes, your plasma driven jet engine can work.
" -Ferrell

How hot would the plasma need to be, even if the compressor design is utilized, and what would be the upper limit of plasma arcs powered by a generator onboard any possible aircraft?

And I'll take it that there are no designs of a fusion equivilent to the Nuclear Lightbulb?

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Sabersonic said...

Darn blogger won't let me post my earlier reply due to the HTML links I had in it. Oh well, third times the charm as they say.

"If your fusion plasma is providing all the thrust it's just a fusion torch. If you're pulling fusion plasma for heat, it's the standard Brayton cycle and would work."-Chris

Actually I was thinking of something a little low in power output, something that would fit on a conventional aircraft design. I'm just wondering if the basic premise is possible since I heard of a Plasma Jet Engine for aircraft on a Sci-Fi show.

"if the plasma can get hot enough to ignite an oxygen/nitrogen fire, then yes, your plasma driven jet engine can work."-Ferrell

How hot would the plasma need to be, even if the compressor design is utilized, and what would be the upper limit of plasma arcs powered by a generator onboard any possible aircraft?

And I'll take it that there are no designs of a fusion equivilent to the Nuclear Lightbulb?

And I think Ferrel meant WR 104, not Eta Carinae.

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Milo said...

Sabersonic:

"I'm just wondering if the basic premise is possible since I heard of a Plasma Jet Engine for aircraft on a Sci-Fi show."

During the Cold War, both the US and USSR speculated on fission-powered airplanes. In principle a fusion reaction should be able to do anything a fission reactor can. All jet engines essentially work on heat, so any sufficient heat source should do (although I'm not entirely sure - I'm not familiar with the workings of jet engines, but a cursory reading suggests that they normally combust their fuel inside the air to be expelled, which of course isn't an option for nuclear fuel). You could also make a turboshaft engine where all energy goes towards spinning a propellor. Overall though, a jet engine is simply a rocket engine that takes its reaction mass from the air intake rather than keeping it onboard, so any sufficiently miniaturizable thermal rocket design should also work on an airplane. The crucial question is if your fusion reactors can be scaled down to fit on an airplane - since fusion technology is mostly speculative and and science fiction work will have to make the details up, this is ultimately up to you.

A sufficiently powerful electric plant could presumably also power a completely electric engine. This would be more reminiscent of battery-powered model airplanes than anything, but if the fusion plant is powerful enough it could be a viable system for larger craft as well. Many solar-electric craft have already been flown, though not with fighter jet level performance.

The projects were scrapped when ICBMs were developed to fulfill the same strategic role more simply.


"And I think Ferrel meant WR 104, not Eta Carinae."

WR 104 and Eta Carinae are both supernova candidates at roughly the same distance from us. However, WR 104 might be pointed at us while Eta Carinae clearly is not.

Brian said...

Wikipedia says that new data indicates that WR 104 is 30 to 40 degrees away from pointing at us. :)

http://en.wikipedia.org/wiki/WR_104

Also see

http://www.universetoday.com/23342/wr-104-wont-kill-us-after-all/

:)

jollyreaper said...
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jollyreaper said...
This comment has been removed by the author.
Luke said...

Ferrel:

A proton/antiproton atom would decay even faster than positronium. Such an atom would occupy a much smaller space, so you can think about it as giving the proton and antiproton that many more chances in a given time to encounter each other and annihilate. Plus, the size of such an atom is not much larger than the proton and antiproton themselves - they will be practically touching the entire time.

Regarding the jet engine and alternate methods of powering it: A jet engine works like this - suck air in, compress air, heat air, let air expand out the back, make expanding air do work to both compress new air and whatever else you want it to do (run a generator, push an airplane, etc.). In the "heat air" step you can use any method you want to heat the air. Injecting and igniting fuel works well now because hydrocarbon fuel stores a lot of energy for a given mass and volume when it burns in oxygen, so burning kerosene cuts down on the weight a lot. If you have compact energy generating or storing systems, you could use them instead. For example, leak fusion plasma into the compressed air, or heat the compressed air with fusion neutrons, or discharge an electric arc across the air with power from a generator or stored energy ultra-super-mondo-capacitor or superconducting solenoid or whatever, or detonate an AIM pulse unit or high explosive charge inside the compressed air every so often, or shoot a laser or microwave beam into the compression chamber to strike a plasma spark and absorb the rest of the beam, or send sonic shockwaves ricocheting around in the compression chamber, or anything else you can think of. If your reactor or generator or ultra-super-mondo-capacitor or whatever is heavier than the kerosene you would use for fuel, it doesn't make much sense to use that instead of kerosene, which is why jet aircraft do use kerosene.

Tony said...

Luke:

" If your reactor or generator or ultra-super-mondo-capacitor or whatever is heavier than the kerosene you would use for fuel, it doesn't make much sense to use that instead of kerosene, which is why jet aircraft do use kerosene."

Slight quibble...

On Earth you are correct, but in othe contexts there could be economic reasons why you would want to use a non-fossil fuel power soruce. For example, in a space opera setting where you don't have gravity control, but you do have compact fusion generators, you'd want to use those for ground to space shuttles, because they could be used without significant ground infrastructure. Also, if you wanted to jet around in an atmosphere like Titan's or Venus's, you couldn't use combustion for power anyway.

UmbralRaptor said...

Er, you can use combustion for jetting around Titan. Granted it's a lot less efficient since you're lugging around liquid oxygen instead of kerosene...

Anonymous said...

Ok, my Super Compact Rocket Engine isn't going to work *sigh*...well, back the the drawing board! I guess for now I'll just use an ion-beam ignited fusion drive, until I can come up with some way to plausibly come up with a wire-fed high energy plasma drive.

Good to hear about WR 104 :)

On Titan, an internal combustion engine would use liquid oxygen as fuel and suck in the methane rich air of the moon.

Ferrell

Rick said...

That the Crab Nebula still hosts violent events is awesome but hardly surprising - sort of like a hurricane spawning tornadoes.


On jet engines, I'd add the proviso that jets (at least as we know them) involve direct contact between substantial quantities of heated air and turbine blades, etc.

Even setting aside all the other problems of fusion, I suspect that putting air in contact with a fusion plasma would simply quench the fusion plasma. It would be roughly like trying to run a conventional jet engine underwater.

Sabersonic said...

For the Plasma Heated (mind you, I didn't mean Fusion Plasma in my original inquiry, just the standard electrically generated Plasma Arc that many of us are familiar with) Jet Engine, it is theoredically plausible so long as said plasma heats the surrounding air high enough to cause thrust akin to conventional kerosene jet engines.

Granted, kerosene and other hydrocarbons such as petrolium are viable when local sources are willing to export said resource at economically reasonable exchanges, let alone political.

What I mean by political is that if a nation that's abundant in a resource that's essential to either heavy industry, electronics, or both, severely limits export of said resources as suggested By this blog entry for political gain and demands (and that any possible form of military action is unwise to secure said resource lest it leads to an international scandal and domestic unpopularity), then it might give a kind of incentive for nations that have space access technology to invest in off-world resource mining such as NEOs since it would be comparatively cheaper in comparison. Not exactly the "Earth Used Up" plot for mass colonization of space, but it just might fit the bill.

Though then again, I have been wrong before.

Which reminds me.

"It would be roughly like trying to run a conventional jet engine underwater." - Rick

Is there any benefit to directly heating the water in a Hydro Jet instead of just pumping the water out at high speed?

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jollyreaper said...

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

On January 1, 1957, the U.S. Air Force and the U.S. Atomic Energy Commission selected the Lawrence Livermore National Laboratory's (LLNL) predecessor, the Lawrence Radiation Laboratory, to study the feasibility of applying heat from nuclear reactors to ramjet engines. This research became known as "Project Pluto". The work was directed by Dr. Ted Merkle, leader of the laboratory's R-Division.



The "Tory-IIC" prototype
Originally carried out at Livermore, California, the work was moved to new facilities constructed for $1.2 million on 8 square miles (21 km2) of Jackass Flats at the NTS, known as Site 401. The complex consisted of 6 miles (10 km) of roads, critical assembly building, control building, assembly and shop buildings, and utilities. Also required for the construction was 25 miles (40 km) of oil well casing which was necessary to store the approximately 1,000,000 pounds (450,000 kg) of pressurized air used to simulate ramjet flight conditions for Pluto.

The principle behind the nuclear ramjet was relatively simple: motion of the vehicle pushed air in through the front of the vehicle (ram effect), a nuclear reactor heated the air, and then the hot air expanded at high speed out through a nozzle at the back, providing thrust.

The notion of using a nuclear reactor to heat the air was fundamentally new. Unlike commercial reactors, which are surrounded by concrete, the Pluto reactor had to be small and compact enough to fly, but durable enough to survive a 7,000-mile (11,000 km) trip to a potential target. The nuclear engine could, in principle, operate for months, so a Pluto cruise missile could be left airborne for a prolonged time before being directed to carry out its attack.

Anonymous said...

(SA Phil)

It would seem feasible to use a Nuclear Thermal Ram Jet/Scram Jet in conjunction with a Nuclear Thermal Rocket to make a Space Plane work.

Just switch from Air to hydrogen as a propellant once you were at a high altitude.

Tony said...

Rick:

"Even setting aside all the other problems of fusion, I suspect that putting air in contact with a fusion plasma would simply quench the fusion plasma. It would be roughly like trying to run a conventional jet engine underwater."

Isn't that the object of the exercise? One would use the fusion reactor ro generate plasma that would giv up it's heat to a mcuh larger volume of reaction mass, which would be expelled for thrust.

Winchell Chung said...

Sabersonic said...
1) Is there a Fusion version of the Nuclear Lightbulb?


I never saw such a design, and I've seen quite a few propulsion designs. I have my doubts, it was hard enough to prevent a fission reaction from vaporizing a transparent wall, a fusion reaction would just be that much worse.

Anonymous said...

S A Phil said:"It would seem feasible to use a Nuclear Thermal Ram Jet/Scram Jet in conjunction with a Nuclear Thermal Rocket to make a Space Plane work."

Except that it was found that the nuclear ramjet would produce huge quantities of fall-out in its exhast...Pluto's last design didn't even have a warhead, just used its exhast to contamanate huge swaths of the old Soviet Union.

Ferrell

Anonymous said...

(SA Phil)

Well yeah, that would be an issue.

Do you not have a similar problem with the most types of Fusion?

(neutron radiation that is)

Anonymous said...

SA Phil: With fusion plasma, the neutron radiation depends on the specific reaction and how you introduce the plasma into the air stream. Luke or Milo could tell you more (and in greater detail), then I can.

Ferrell

Luke said...

SA Phil:

The type of fusion that is most likely to be practical (D-T) will produce an enormous number of high energy, highly penetrating neutrons. These will stream from the reactor in much greater intensity than from a fission reactor of equal power and irradiate everything around them. You do not get fall out in the exhaust - once the reactor leaves you don't have any more neutrons irradiating the area. Neutrons can activate materials that they hit (making them somewhat radioactive for a few days to months), but unlike radioactive particles shot into the exhaust stream you don't get atmospheric activity that gets spread over a wide area (or more properly you get minimal atmospheric activity - most isotopes in the air can absorb a neutron or two without becoming radioactive, and those that do become radioactive after the absorption of one neutron are not likely to absorb a neutron). So you get a pulse of radiation as the fusion jet flies overhead, and low level local radioactivity that lingers for a short while.

The only other vaguely plausible fusion reaction (D-3He) will give you about as many neutrons as a fission reactor, but without the fission reactor's radioactive contamination (although you will get some neutron activation, as discussed above). For a given reactor technology, you will also get about 80 times less power with D-3He than with D-T (which may mean a net loss of power if you need to supply power to keep the reactor going).

Luke

Luke said...

Minor correction - D-D is also plausible, but offers no benefit over either D-T or D-3He (it is as hard to ignite as D-3He and puts out lots more neutrons).

KraKon said...

Just catching up...

KraKon said...

There

Anonymous said...

(SA Phil)

Luke,

Thanks.

So basically it sounds like a fusion liftoff vehicle in an atmosphere could be a problem.

Since you would be flying through water vapor, dust, etc and irradiating those as you go.

Milo said...

Tony:

"On Earth you are correct, but in othe contexts there could be economic reasons why you would want to use a non-fossil fuel power soruce."

Kerosene doesn't have to be a fossil fuel. Developing a renewable biofuel with similar chemical characteristics as kerosene would - in the time frame we're discussing - be easier than inventing a completely revolutionary engine. Even if we don't get exactly kerosene, then redesigning a combustion engine to use some other fuel would be easier than switching to some other principle besides combustion.


"Also, if you wanted to jet around in an atmosphere like Titan's or Venus's, you couldn't use combustion for power anyway."

You could if you carried your own oxygen (while still using the native atmosphere for reaction mass). This is in no way unfeasible. But you're right that this would require a change to the engine designs.



UmbralRaptor:

"Er, you can use combustion for jetting around Titan. Granted it's a lot less efficient since you're lugging around liquid oxygen instead of kerosene..."

Ferrell:

"On Titan, an internal combustion engine would use liquid oxygen as fuel and suck in the methane rich air of the moon."

Heh, that's a good point. The methane in Titan's atmosphere makes a decent fuel, so you would only need to carry something for it to react with.

But even in a totally inert atmosphere, you can just carry kerosene and oxygen in separate fuel tanks.



SA Phil:

"Do you not have a similar problem with the most types of Fusion?"

Umm, no. Fusion doesn't generate anywhere near the radioactive fallout that fission does.

Neutrons are somewhat problematic, but the threat is mostly confined to the immediate environment of the reactor while it's running, not to anywhere the reactor has flown past in the last few months.

There is some permanent radioactivity due to neutron activation, but that's still minor compared to a fission exhaust.

And some fusion reactions are aneutronic, or mostly aneutronic (making what remains easier to shield against). Deuterium-helium, in the latter category, has a very good energy density.



Luke:

"So you get a pulse of radiation as the fusion jet flies overhead,"

Which brings to mind the whole "time, shielding, distance" doctrine of radiation safety. How far overhead does a fusion reactor has to be in order to not pose a health hazard to people on the ground despite it not having good shielding?

Tony said...

Milo:

"Kerosene doesn't have to be a fossil fuel. Developing a renewable biofuel with similar chemical characteristics as kerosene would - in the time frame we're discussing - be easier than inventing a completely revolutionary engine. Even if we don't get exactly kerosene, then redesigning a combustion engine to use some other fuel would be easier than switching to some other principle besides combustion."

"Fossil fuel" in the sense I was using it is shorthand for "organic compound burned in oxygen". It comes from US Navy nuclear engineers calling oil or JP burning ships "fossil fuelers". They'd still call them fossil fuelers if they burned wood or cow sh!t.

Having said that, replacing even a significant fraction of current petroleum usage with biofuels is going to involve burning food. I've got problems with that, and I don't think I'm the only one.

Anonymous said...

(SA Phil)

How do you shield the area around the Fusion reactor?

I can see a shadow shield for the crew of the vehicle or even shielding a whole compartment.

But the reactor itself can't be shielded on the scale of a launch vehicle - it would melt, would it not?

You would need some kind of open cage design?

-----
Possibly those things could be designed around.

But otherwise - that is why I was speculating on the piggyback aircraft / launch vehicle idea.

Anonymous said...

(SA Phil)

Bio-kerosene might not be as bad as Ethanol.

Kerosene is nearly diesel. You can make Bio-Diesel with organic waste. You dont need anything that is actually food quality.

Jim Baerg said...

Milo: "Kerosene doesn't have to be a fossil fuel. Developing a renewable biofuel with similar chemical characteristics as kerosene would - in the time frame we're discussing - be easier than inventing a completely revolutionary engine."

It doesn't have to be a biofuel either. See this proposal for making fuels from CO2 extracted from air plus water & an energy source. http://www.lanl.gov/news/newsbulletin/pdf/Green_Freedom_Overview.pdf
I don't see any reason that something of the sort can't be done, but I'll believe the cost estimates when they've got a working facility. However, at least it doesn't involve burning food.

We might want to go with a different fuel than gasoline or kerosine though if we are making the fuel from something other than petroleum. Apparently dimethyl ether (DME) burns very cleanly in diesel engines & a spill is harmless aside from the fire hazard. We might as well shift to something cleaner if we have to change fuel sources.

Also see the notion of ammonia as a fuel. http://www.nh3fuelassociation.org/

DME or NH3 would work reasonably well with existing technolgies, unlike eg: hydrogen or some yet to be invented super battery.

Luke said...

Milo:

How far overhead does a fusion reactor has to be in order to not pose a health hazard to people on the ground despite it not having good shielding?

From Wikipedia, a GE CF6-80C2 Brayton high-bypass turbofan jet engine puts out 44.7 MW. If we assume that our fusion jet has the same heat output, then you end up with about 450 MW of neutrons (making the assumption here that the neutrons contribute very little to heating the air in the compression chamber - probably a good assumption since 14 MeV D-T fusion neutrons are very penetrating).

A dangerous radiation dose is about 1 Gy. 10 Gy is quite lethal. 0.1 Gy leads to mild radiation sickness. I am not going to worry about chronic radiation poisoning such as increased cancer risk in this analysis. 1 Gy is an absorbed dose of 1 J/kg. Approximating an adult human as 100 kg and 0.5 m^2 of cross sectional area, and figuring that hydrogenous stuff like the human body is much better at stopping neutrons that metals and composites like a jet turbine so that all the incident flux is absorbed by the body*, then 10 seconds of hovering at 100 m altitude will deliver a dose of about 20 Gy, which will kill a person within days.

In level flight at an altitude of 100 m and a speed of 300 m/s (just below the speed of sound), an exposed person on the ground would receive a dose of nearly 2000 Gy.

At higher altitudes the air itself starts to add shielding. If you assume half of the neutron flux is attenuated every 500 meters or so, you will not be terribly wrong. A fusion jet cruising along at a stratospheric altitude of 10 km would deliver something like 20 Gy without atmospheric shielding, including the air the dose goes down by a factor of something like 2^20 ~ 1,000,000. So at many kilometers altitude fusion jets are probably safe.

* This approximation might be off by a factor of 2 or 3 at 14 MeV, but not 10 or 100.

Luke said...

Tony:

replacing even a significant fraction of current petroleum usage with biofuels is going to involve burning food.

We don't eat switchgrass or Jatropha or hybrid poplars, nor do we eat corn stover, yard waste, or logging slash. Switchgrass and Jatropha grow where it is not possible or economical to grow food crops; the corn stover, yard waste, logging slash, restaurant food waste, and the like you might as well use for biofuel, it certainly is not displacing anything from our food supply. And then there are algal biofuel reactors. How a tub of tubes full of salty green pond scum in the middle of the desert in the American Southwest interferes with getting food on my table, I cannot fathom.

Milo said...

Luke: So if I understand this correctly, the shielding afforded by air molecules is a bigger factor in protecting you than the distance itself?

Luke said...

Milo:

Sort of. There is a geometric 1/r^2 term and an attenuation exp(-r/A) term (r is distance, A is an absorption length - the exp(-r/a) part is mathematically equivalent to halving the dose at a distance of A ln(2), so A ln(2) corresponds to the roughly half a km given above). You have to take both into account - at 450 MW the attenuation term alone (equivalent to a beam of neutrons perfectly aimed at the target) would give you a dose of 450 Gy/s even with a factor of 1,000,000 for attenuation.

Also note that the attenuation of a factor of 2 at every half kilometer is very approximate, and small differences here can have a significant effect at a fixed distance - if the neutrons actually attenuated by a factor of 2 every 600 meters instead of every 500 meters, at 10 km the neutrons would have attenuated by a factor of 10,000 instead of 1,000,000. On the other hand, keeping the distance the same multiple of attenuation lengths - 12 km rather than 10 km in this example - gives the same attenuation factor.

So I just looked at the actual nuclear data rather that relying on memory that was a few years old. Using the actual total cross sections for neutrons at 14 MeV (1.6 b for both N-14 and O-16) and the density of sea level air, I get an attenuation distance A of about 116 meters (so you lose half your incident flux every 80 meters). Now we get to the complicated part - most of those neutrons are not lost, they are scattered and keep most of their incident energy. You will need several scatterings before the neutrons lose enough energy to make much of a difference (when the energy gets low enough, the rate of scattering increases significantly so that the neutrons more or less get stopped for long enough to get absorbed). On the other hand, when the neutrons scatter, they end up going in a random direction. This means that past a few hundred meters, you need to include the diffusion of the neutrons into your model, which makes it even more complicated. This is usually where I stop trying to do the analysis with pencil and paper and go to computer simulations made for radiation transport. In any event, at distances of several km attenuation, diffusion, and geometric dispersal all combine to reduce the dose to something that is probably manageable (again, neglecting chronic exposure issues).

Luke

Anonymous said...

(SA Phil)

Luke, Thanks. Sounds like a lot of radiation then.

So much so that even in Tony's shielded "8%" version - it would be too much. At least for D-T Fusion.

Which implies that a fusion launch vehicle is problematic -- and not just the fusion tech.

Anonymous said...

(SA Phil)

Back to fission for a moment - the reason it is unsutable is because they are open core and lead to fallout exhaust.

What about closed core fission designs. How plausible would that be for a launch vehicle?

You could use intake air for propellant at low altitudes, tanked propellant at high altitudes to orbit.

Tony said...

Luke:

"We don't eat switchgrass or Jatropha or hybrid poplars, nor do we eat corn stover, yard waste, or logging slash. Switchgrass and Jatropha grow where it is not possible or economical to grow food crops; the corn stover, yard waste, logging slash, restaurant food waste, and the like you might as well use for biofuel, it certainly is not displacing anything from our food supply. And then there are algal biofuel reactors. How a tub of tubes full of salty green pond scum in the middle of the desert in the American Southwest interferes with getting food on my table, I cannot fathom."

You have to think in terms of systems, Luke. Stuff that grows on bad ground (wild grasses), or requires significant processing to extract reactable organics (wood), requires significant infrastructure investment and shipping water to the desert (algae farms) are all marginal energy sources. It turns out that the highest energy yield biofuels are in fact food crops. They convert relatively easily into alcohol, they grow on accessible, easy to cultivate and harvest lands, and they require a minimum of added energy for high yield.

Even with government susidies, the only biofuels that come close to being practical are American corn and Brazilian sugar cane. And that's burning food.

Anonymous said...

(SA Phil)

Again I think there should be a distinction between Cetane rated fuels and Octane rated fuels

Tony you seem to be talking more about Ethanol.

Bio-Diesel is a bit different.

As far as Ethanol I agree with you, at least near future. All the dreams of non-food quality sources seem to not have worked as well as the invisioners hoped.

Tony said...

SA Phil:

"Tony you seem to be talking more about Ethanol.

Bio-Diesel is a bit different."


You still need vegetable oil or animal fat feedstock. Vegetable oil takes, well...oily vegetation. That means fatty plants, and those are generally used for food. Likewise, due to their high energy concentrations, animal fats are synonymous with food, in almost any form you find them.

Luke said...

Tony:

Stuff that grows on bad ground (wild grasses), or requires significant processing to extract reactable organics (wood), requires significant infrastructure investment

So does petroleum-based oil.

and shipping water to the desert (algae farms)

You can pump up water from aquifers unsuited to agricultural use (due to salt content) for algae.

Even with government susidies, the only biofuels that come close to being practical are American corn and Brazilian sugar cane.

Currently. In a decade or so, I'm not so sure.

Tony said...

Luke:

"So does petroleum-based oil."

Let me make explicit what was implicit: on a per kilowat hour basis. Petroleum is much more concentrated energy. When using it, we're leveraging millions of hour/acres of insolation, further concentrated by millions of years of gelological pressure. I've personally seen both grass fires and burning oil fields. You can take my word for it that petroleum is more energetic than vegetation.

"You can pump up water from aquifers unsuited to agricultural use (due to salt content) for algae."

You can desalinate water. It adds to the energy cost of agriculture, but given the current state of aquifers everywhere, I'm pretty sure that will happen long before we use that water to grow pond scum for burning.

"Currently. In a decade or so, I'm not so sure."

Always "[i]n a decade or so". That's another assertion I'd love to have a dollar for every time I heard it.

Anonymous said...

(SA Phil)

My point was it is easier on a relative basis to produce a bio-diesel than an ethanol from vegetable waste.

Bio-diesel is a backburner solution not because has all the same problems as ethanol, but rather as long as you are making gasoline you are going to have fuels at the diesel end also. (refinery realities)

So you wouldn't say produce both bio-diesel and gasoline. You would need to pair it with increased ethanol.

That was why when they were tossing around the E22 flex fuel plan they were suggesting a 50/50 bio-diesel/Diesel mix for California diesel only. (In one proposal)

Tony said...

SA Phil:

"My point was it is easier on a relative basis to produce a bio-diesel than an ethanol from vegetable waste."

Who told you that? As previously mentioned, biodiesel feedstocks have to contain a high concentration of lipids. High concentrations are found in seeds, not in stalks. Seeds are product, stalks are waste.

Anonymous said...

Tony,

Who told you that?

----
The Alternative fuels guys

SRL
Ford Motor Company
Circa 1998

You forget I worked in Diesel Development for a while.

Prior to that I did a little bit with the Flex Fuel and other projects.

(SA Phil)

Tony said...

SA Phil:

"You forget I worked in Diesel Development for a while.

Prior to that I did a little bit with the Flex Fuel and other projects."


Okay...and it never occurred to you to ask where the lipids were going to come from in wheat or corn chaff?

Tony said...

For that matter, where were the precursor sugars for ethanol going to come from in chaff? They don't make white lightning out of straw, you know.

Nothing personal, Phil, but were they really getting away with that in a company full of college educate people?

Anonymous said...

(SA Phil)

I already said I agree with you on the Ethanol thing.

Your definition of "waste" might be a lot narrower than the people actually designing these fuels however.

No one at Alt Fuels ever said -- "here is a corn stalk, I can make fuel out of it."

With your current definition you have set up a straw man argument. (heh heh)

Milo said...

Tony:

"Always "[i]n a decade or so". That's another assertion I'd love to have a dollar for every time I heard it."

We are talking about technology that would be available to people living in an extraterrestrial colony. It's possible that we'll perfect affordable space travel before we develop efficient biofuels, but to my ears the latter objective sounds easier.

Tony said...

SA Phil:

"With your current definition you have set up a straw man argument. (heh heh)"

May the Basement Cat take you!

Seriously, we grow plants in order to harvest their lipids, sugars, and fibers. I don't know of much agricultural waste that has significant energy value.

Anonymous said...

(SA Phil)

I believe an alternative definition of "waste" is:

Anything which might normally be thrown away.

By that definition there is plenty of energy value in plant waste.

Of course it could be argued that in every sector of modern life we throw away vast amount of things which have significant value.

That will probably not be true in the mid-future.

In the mid-future however you could also have gene-engineered plants that will grow almost anywhere and produce the right combination of ingredients to make bio-kerosene.

Luke said...

Tony:

Let me make explicit what was implicit: on a per kilowat hour basis. Petroleum is much more concentrated energy. When using it, we're leveraging millions of hour/acres of insolation, further concentrated by millions of years of gelological pressure. I've personally seen both grass fires and burning oil fields. You can take my word for it that petroleum is more energetic than vegetation.

This makes no sense. The rate of burning of the raw source material has no relevance to the energy content of the processed fuel. Crude oil needs to be chemically broken up and put back together again to make it useful, so does biomass. At this point it is not clear which will end up taking more infrastructure, because biofuel tech is not yet mature.


You can desalinate water. It adds to the energy cost of agriculture, but given the current state of aquifers everywhere, I'm pretty sure that will happen long before we use that water to grow pond scum for burning.

You need water for any sort of energy source, from petroleum extraction and processing, to nuke plants, to manufacture of solar panels. An algal bio-reactor is no different, and with such a bio reactor you could use poor quality water.

Algae is a very promising biofuel source. It is not perfected yet, but to discount it is pure folly.

Always "[i]n a decade or so". That's another assertion I'd love to have a dollar for every time I heard it.

And I'd love to have a dollar for every idiot who was caught flat footed because they thought nothing was going to change.

biodiesel feedstocks have to contain a high concentration of lipids. High concentrations are found in seeds, not in stalks. Seeds are product, stalks are waste.

There are ways of doing it. Worst case scenario is to break it up into syngas and reconstruct your fuel. Better is to use catalysts to break up the cellulose and possibly the lignin and turn it into hydrocarbons.

For that matter, where were the precursor sugars for ethanol going to come from in chaff? They don't make white lightning out of straw, you know.

Cellulose is a sugar polymer. Break it up, and you have sugars.

Seriously, we grow plants in order to harvest their lipids, sugars, and fibers. I don't know of much agricultural waste that has significant energy value.

All cellulosic plant products have about 20 MJ/kg of energy content. We are now figuring out how to use it.

Tony said...

Re: Luke

When you're 46 like me, and everything that you thought would happen for sure in the last 20 years is bad joke, come tell me then about biofuels and every other wild scheme you believe in.

Luke said...

Tony:

What a sad world you must live in. I'm 7 years younger than you, and many of the things I dreamed about as a child and young adult have already come spectacularly true, along with a host of other really awesome stuff that I never even expected. So while I pity you and your universe, I'm glad it is not the one I live in.

Tony said...

Luke:

"What a sad world you must live in. I'm 7 years younger than you, and many of the things I dreamed about as a child and young adult have already come spectacularly true, along with a host of other really awesome stuff that I never even expected. So while I pity you and your universe, I'm glad it is not the one I live in."

The last 20 years has been "spectacular" in terms of dream realization? I think that's all we really need to know, isn't it?

Tony said...

Seriously, Luke, just what is it that you do?

Anonymous said...

Hey guys, when Rick named this entry "A Little Blowup" he didn't mean between the commentators... :>

Anyway, What we use to power cars, ships, planes, etc here on Earth will be different from simuler vehicles on other worlds; Titan can us internal combustion engines with liquid oxygen in the tank instead of gas, but Mars will need other solutions; airless moons, minor planets, large asteroids will need something different again. It might be fun to come up with vehicles for these differnt enviornments; what does everyone else thing about that?

Ferrell

Jim Baerg said...

Ferrel: "What we use to power cars, ships, planes, etc here on Earth will be different from simuler vehicles on other worlds;"

In _The Case for Mars_ Zubrin figured the best power source for Martian rovers would be methane-oxygen combustion engines & the power to make methane & oxygen from CO2 & water would come from a small nuclear reactor. It sounds likely to me.

Tony said...

Ferrell:

"Hey guys, when Rick named this entry "A Little Blowup" he didn't mean between the commentators... :>"

Sorry. But there's very obviously a disconnect that's hampering communications with somebody I should have more in common with. I'm past the disagreement and I'm just trying to figure out what the disconnect is.

Tony said...

Jim Baerg:

"In _The Case for Mars_ Zubrin figured the best power source for Martian rovers would be methane-oxygen combustion engines & the power to make methane & oxygen from CO2 & water would come from a small nuclear reactor. It sounds likely to me."

For at least the first decade os Mars visits, Zubrin was figuring on bringing the hydrogen along to make the methane, since there was no guarantee that sufficient water would be at the landing site. of course, I've always wondered about that from a practical standpoint. Aside from the superior storability of methane, is there a real advantage to producing it? Does a methane molecule reacted with oxygen realize a higher energy release than for molecules of hydrogen>

Milo said...

Ferrell:

"It might be fun to come up with vehicles for these differnt enviornments; what does everyone else thing about that?"

More interesting than what kind of propulsion you use is what kind of vehicle you're propelling in the first place. You can't have an airplane on an airless world. On Mars, there's enough air for some aerodynamics, but you'll need different designs than on Earth (different air density, different gravity).

If you live in domed cities, then travel between the domes will require either pressurized vehicles or subways running through pressurized tunnels (and the latter is only suitable for charted routes, not exploration). But inside the domes, wherever there's enough space to use vehicles at all, you'll be able to use more normal urban vehicles as we know them on Earth.

Barring a massive terraforming effort, though, Titan is the only other place where a boat will be useful. (Submarines might be worthwhile for exploring Enceladus and Europa, but surface ships need not apply.)

In places with light gravities, "bounciness" would be a serious problem, where driving hard enough over a bump on the ground can launch you quite far into the... umm, not air since there's no air, but off the ground (where you can't control the vehicle). At the very least, being able to land safely from an unexpected bounce would be a design factor. Wheels and tires may look different.

In places with very light gravities, you may be better off gripping onto the ground through some means rather than using wheels. (Can't use suction cups in vacuum, though!)

My final thought is that we're fairly familiar with shapes of both artificial vehicles and naturally evolved animals adapted to travel through liquids or gasses, but I have no idea what would work well for moving through a supercritical fluid. Of course, all supercritical fluids have ridiculously high pressures, so just keeping your vehicle intact will pose design constraints.



Tony:

"For at least the first decade of Mars visits, Zubrin was figuring on bringing the hydrogen along to make the methane, since there was no guarantee that sufficient water would be at the landing site."

You would, of course, be wanting to recycle your combustion products. Rather than venting them through an exhaust pipe, you'll try to capture them and store them in a seperate tank until you can carry them back to the nuclear reactor where you'll reprocess them into fuel.


"Aside from the superior storability of methane, is there a real advantage to producing it? Does a methane molecule reacted with oxygen realize a higher energy release than for molecules of hydrogen?"

According to this, methane produces 55.6 kJ/g, while hydrogen produces 143 kJ/g, so hydrogen is the clear winner. However, a gram of methane is easier to store than a gram of hydrogen. By volume, at normal pressure/temperature, methane gives 37.8 kJ/liter and hydrogen gives 10.8 kJ/liter. If you can compress the hydrogen, things potentially become different (but then, if you could compress hydrogen, you could also compress methane).

For what it's worth, carbon is more available on Mars than hydrogen, so the only significant cost in making methane is that of the energy you're pouring in.

Sabersonic said...

Wow, never thought my innocent little question could spark such a debate on alturnative fuels.

Speaking of questions:

"I never saw such a design, and I've seen quite a few propulsion designs. I have my doubts, it was hard enough to prevent a fission reaction from vaporizing a transparent wall, a fusion reaction would just be that much worse. " - hell Chung

So I'll take it that there's no way for the thermal energy of nuclear fusion to heat up remass without it having all of said thermal energy comming out of the back end of a rocket nozzel like a bad Bell Grande? Granted, there's the idea of moderating the heat exchange to managable levels but then again it could be argued that it woudl be no better than nuclear fission.

And I'll take it that heating water in a hydrojet like heating air in a jet engine isn't going to be that efficient/has a whole host of problems that make it problematic at best?

And speaking of problematic ideas, I'll take it that the whole resource Embargo and/or limited trade for political gain of a nation instead of the whole troupe of "Earth Being All Used Up" is just as bad a motivator for space exploitation, correct?

- Hotmail Address
Gmail Address

Thucydides said...

Specific Energy Density (MJ/kg) of hydrogen is 120, but hydrogen is difficult to use due to is being a deep cyroghen or needingto be highly compressed to use as a fuel. Hydrogen also embrittles metal, seeps out through the smallest gaps of pores and is generally a pain in the behind.

Hydrocarbons have varying energy densities, Gasoline is @ 45 Mj/kg while Diesel is @ 48. Hydrocarbons are solids and liquids at most sensible temperatures and are relatively non toxic, something to consider inside a self serve gas station. if we go by volumetric energy density then Hydrogen comes off very badly; 8.5 MJ/L compared to 32 with my car and 40.3 for diesel.

Most syngas and synfuel schemes fall apart when the truth comes out at last and it takes almost as much energy to convert as you could get a cold one for you.

Thucydides said...

? Blogger is changing the posts?

The last paragraphs should read:

Hydrocarbons have varying energy densities, Gasoline is @ 45 Mj/kg while Diesel is @ 48. Hydrocarbons are solids and liquids at most sensible temperatures and are relatively non toxic, something to consider inside a self serve gas station. if we go by volumetric energy density then Hydrogen comes off very badly; 8.5 MJ/L compared to 32 MJ/L for gasoline and 40.3 for diesel.

Most syngas and synfuel schemes fall apart when it takes almost as much energy to convert raw materials into synfuel as you could get out of the synfuel.

Rick said...

it takes almost as much energy to convert as you could get a cold one for you.

I don't know how the hell that happened, but after reading this thread I certainly feel like reaching for a cold one.

Hey guys, when Rick named this entry "A Little Blowup" he didn't mean between the commentators... :>

Thank you, Ferrell. It seems like several people could stand reaching for a cold one at this point - the substance of this thread is fascinating, but the needless aggravation sux.

Fundamentally there is merit to both arguments being made, but they are inherently talking past each other to a degree - which is no excuse for a sniping tone on anyone's part.

Lots of extraordinary progress is being made in these technologies, but there is also an awful lot of vaporware out there, stuff that has been 10 years away for 20 years.

The bottom line, so far as I can see, is that regardless of 'peak oil,' we're certainly near the end of plentiful cheap oil. So long as oil was inherently cheap the motivation to pursue alternatives was limited, but as the underlying cost of getting at oil rises, there will be major investment in alternatives.

This is doubly fortunate, given that we'd need to shift over even if there was plenty of easy-to-tap oil still out there.

Many of the proposed techs may not pan out, but some of them probably will. Humans are omnivores, but our diet is not just about energy, and there is likely an awful lot of stuff that we can't eat, but can economically burn.

If this is not the case, things will get very, very bad in this century, and space travel will be the last thing on anyone's mind.

Anonymous said...

Milo: reading your thoughts about vehicles for light or very light gravity worlds brings to mind a mechanical Gecko...as amusing as that image is, it is based on a real-world walking machine developed and used in Oregon for low-impact logging.

Ferrell

Anonymous said...

Hmm...a replacement for oil...well, biodiesal or genetic engineered bio-oil plants; methane or methane derived fuels; mixtures of nitrogen compounds or some other chemical fuel; synthetic hyrocarbons; or, very dense batteries.

All of these have both pros and cons and I don't see any clear advantage of any of these over petrolium.

Ferrell

Thucydides said...

The best replacements for hydrocarbons are....

hydrocarbons.

The energy density, the ability to remain solid or liquid at normal temperatures, the ease of handling and relatively low toxicity of hydrocarbon fuels make them the energy choice of the future, just as they were the energy choice of the last century.

How we continue to get hydrocarbons is an interesting problem, advanced production techniques like Hydro Frakking are raising the amount of oil and gas that can be produced from existing fields, while weird and wonderful schemes from Methane Hydrates to using genetically engineered bacteria to produce oil analogues (Joule Energy) will be tested for viability.

The other big breakthrough I would expect is some really high density means of storing electricity, since current methods are quite limited (think of the difference between the mass of batteries needed to get a GM "Volt" to run for 40 miles vs the mass of gasoline needed to run the same car 300 miles. The same comparison can be made for the Toyota Prius which despite marketing hype by GM uses very similar hybrid technology with a different weighting between electric/gas power modes).

These are the two big drivers of technology and economics that I can foresee in the near to mid future.

Anonymous said...

(SA Phil)

I think the bio fuels angles came in as a response to provide a source of easy to use chemical rocket fuel (using kerosene and oxygen) without the old oil angle.
------------
------------

In response to Thucydides about Electric vehicles/Hybrids - I have two comments -

First the mass of the battery is reusable, so a direct apples to apples comparison of mass of fuel doesnt really apply for a Earth based land vehicle, really.

For anything in space though...

---
Secondly, the Prius and the Volt are not really all that similar.

The Volt is the Hybrid in the original use of the term. An electric drivetrain that uses a fossil fuel motor to recharge during operation.

The Prius is actually a vehicle with an adjustable powertrain. It has both an electric drive and a gasoline drive motor - and a transmission that can take advantage of one or both. It is only a Hybrid in the current larger sense of the term. In 1995 for example we would have called it a dual drive vehicle instead.

The fancy transmission Toyota came up with for Prius to make it all work was a bit of a surprise really. The idea of dumping cost and warantee headaches INTO the transmission of all things was anathema to the normal way vehicle planners thought at the time.

Thucydides said...

The Volt also uses its IC motor to directly drive the wheels, so can be compared to a Prius, the main differentiation being what proportion of effort is derived from the IC or the electric engine.

The hype of the Volt being a serial electric vehicle where the IC motor did not drive the wheels was a bit odd, since serial electric only makes sense in large vehicles like railway locomotives, huge dump trucks used in strip mines or the Maus MBT which weighed in at 100 tons. Now that it is just an "ordinary" hybrid in today's sense of the word, then sensible comparisons can be made and sensible engineering decisions can be incorporated into the next generation (assuming it lasts long enough to need another generation).

Anonymous said...

(SA Phil)

Hmm I was under the impression they had leveraged the EV1 concept work. Which was an entirely electric powertrain.

It looks like instead, you are correct and I was wrong- they decided to go with this "powersplit" idea.

Serial Hybrids (as the term now seems to be) were the primary direction for most companies in the 1990's.

The Idea was - electric powertrain which can easily use different sources such as:

GM tossed around
*2 stroke Gas
*4 stroke gas
*bigger battery
*Fuel cell

Ford had
*Turbo diesel
*CNG/LP
*Fuel Cell

Mercedes was focussing on Fuel Cells. We were supposed to see a production fuel cell Mercedes in '03.

---------
An interesting tidbit that.

It makes the Volt's dismal sales look even more sad.

Anonymous said...

(SA Phil)

The other side was a cost thing.

To do this dual drive stuff you need a specialized transmission.

Which doesn't make a whole lot of sense for a vehicle that isn't going to sell very well.

Although I suppose GM already had to develop it for their other hybrids.

--
The EV1 instead had no transmission. It had 4 wheel motors with no mechanical differential at all.

They predicted 400,000 miles with zero maintenance for the electric drive components.

Thucydides said...

One of the big drivers of things is the sunk costs and associated infrastructure of existing systems.

IC engines have been around for more than a century so keeping it around for motive power and generation of energy for the batteries is a no brainer.

Fuel cells usable in cars are either PEM types which need pure hydrogen to generate electrical energy, or SOFC's. You now need to deal with two expensive and finicky technologies; PEM's need platinum to work while bulk Hydrogen production on the scale needed would have huge technical hurdles, not to mention the technology needed to store and transport the stuff safely. SOFC's can use hydrocarbons, but need special materials to run the internal reaction at @ 800 C, plus need to be pre heated before they can work.

Of course even if you solve these problems, where is the army of mechanics and techs who can fix them on the road?

Thucydides said...

Oh, the dismal sales probably have to do with the @$40,000 price tag rather than anyone actually doing one to one comparisons with the Prius.

Even the Prius is something of a vanity car, it is "only" $10,000 less to buy than a Volt but is the same size as many cars that sell in the $20,000 range.

Jim Baerg said...

Milo: If you live in domed cities, then travel between the domes will require either pressurized vehicles or subways running through pressurized tunnels.

Pressurized subways seem kind of pointless to me. They would just add air resistance to impede fast travel. Pressurized vehicle on some sort of railway (Maglev?) would be the way to go for routes with enough traffic to justify the cost of building something more expensive than a dirt road. On really low gravity worlds, maglev to hold the vehicle *down* might be useful.

Anonymous said...

Jim Baerg said:"Pressurized subways seem kind of pointless to me. They would just add air resistance to impede fast travel. Pressurized vehicle on some sort of railway (Maglev?) would be the way to go for routes with enough traffic to justify the cost of building something more expensive than a dirt road. On really low gravity worlds, maglev to hold the vehicle *down* might be useful."

Hmmm...makes me wonder what a locomotive would look and operate like on Mars or Titan...

Ferrell

Anonymous said...

=Milo=


Ferrell:

Just like on Earth? You wouldn't exactly be able to vent steam into the air without air, but we haven't used steam locomotives in quite a while. Most modern locomotives don't really have any part of their engine visibly exposed to the outside, so even if some of the design details were different, you wouldn't notice.

Terrain also isn't relevant because you'll be clearing it and laying tracks anyway. The only thing you can't change is gravity.

Anonymous said...

Milo; actually, I was just thinking it would be amusing to see a locomotive chugging away on Titan or Mars...instead of some super-high-tech transportation system that people usually imagine.


Ferrell

Anonymous said...

(SA Phil)

RE: space locomotives

Modern trains are still water cooled I beleive. The Diesel engines use air/water heat echange radiators like cars do.

So a train on mars might need a much larger radiator to compensate for the thinner atmosphere.

While one on the moon might need radiators more like a space craft has.

Nuke/electric trains would be effecitive, assuming you had a colony that needed that kind of capacity.

Nuke/electric would be pretty effective on Earth too .. if anyone would ever let them be built.

Tony said...

On an airless or non-oxygen atmosphere planet, I think I'd use electric trains, even over long distances. If I had to, I'd install solar or RTG powered booster stations at intervals along the line to keep operating current at useful levels.

WRT nuclear power on the locomotive itself, I think one would run into power/weight issues. Also, mobile reactors are a serious safety issue, especially moving through communities.

Anonymous said...

Tony,

WRT nuclear power on the locomotive itself, I think one would run into power/weight issues. Also, mobile reactors are a serious safety issue, especially moving through communities

------------------

A train can mass considerably more than a submarine.

Nuclear Submarines come close to population centers all the time.

Nuclear weapons are handled near population centers as well. I had a friend who loaded nuclear weapons into B52's in Stutgartt at the height of the cold war, they then flew the nuclear weapons over population centers.

I see no reason it could not be done except for "soft reasons" like people not trusting civilans with nuclear power like they do the military, etc.

On a risk basis, its probably significantly lower than pumping flamible gas through aging steel pipes under most of our major cities.


(SA Phil)

Tony said...

SA Phil:

"A train can mass considerably more than a submarine."

And less than 5% of that mass is in propulsion. A nuclear submarine probably has a good 30% or more of it's mass in Propulsion plant.

"Nuclear Submarines come close to population centers all the time."

Yeah, a few score of them do, and they dock at naval bases. That's not the same thing as several thousand, running through people's backyards.

"Nuclear weapons are handled near population centers as well. I had a friend who loaded nuclear weapons into B52's in Stutgartt at the height of the cold war, they then flew the nuclear weapons over population centers."

Do you really think an essentially inert nuclear weapon is the same thing as an operating nuclear reactor? Seriously?

"I see no reason it could not be done except for "soft reasons" like people not trusting civilans with nuclear power like they do the military, etc.

On a risk basis, its probably significantly lower than pumping flamible gas through aging steel pipes under most of our major cities."


Fukushima Daiichi was a static site and was hardened against every conceivable natural and manmade disaster. They didn't concieve of everything. After that experience, I don't think any rational person wants nuclear reactors riding the rails around their country. Hysteria and ignorance no longer need apply as excuses among nuclear enthusiasts (at least the realistic ones). It's quite clear now that nuclear power is a lot more risky than we thought. We make that Devil's bargain for nuclear subs and aircraft carriers, for good and sufficient reasons. We may even make that bargain for civilian power generation for a while longer. Heck, we may even expend our use of nuclear power for that purpose. But mobile reactors on railroads? that's literally crazy.

Anonymous said...

(SA Phil)

RE: Tony's objections

An inert nuclear weapon is potentialy more dangerous than a well designed nuclear reactor.

You cant hijack the nuclear reactor and use it to make a nuclear bomb.

Had the Japan nuclear reactors not overheated there would have been *no* danger. It is possible to design reactors with passive cooling. Those in Japan required substantial active cooling.

---------
I already accounted probable public dislike for the idea in my conditionals. It is a "soft objection" in that we do plenty of things far more dangerous every day in our society, however they have better PR.

-------
As to the mass situation it is really not necessarily a good one. The Submarine also has to deal with water resistance. A V8 engine that gets 15 miles a gallon in a Pickup truck might be lucky to get 2 miles per gallon in a similar mass boat.

You would have to look at the specifics of the reactor you wanted to use as well as the requirements of the train.

(SA Phil)

Tony said...

SA Phil:

"An inert nuclear weapon is potentialy more dangerous than a well designed nuclear reactor.

You cant hijack the nuclear reactor and use it to make a nuclear bomb."


The misappropriation of a nuclear weapon can be guarded against. (Trust me, I know what I'm talking about when it comes to special weapons security.) Mobile reactors, especially in the complex operational environment of railroading, would almost certainly be involved in serious accidents periodically.

"Had the Japan nuclear reactors not overheated there would have been *no* danger. It is possible to design reactors with passive cooling. Those in Japan required substantial active cooling."

You won't have reliable passive cooling in mobile applications. Such systems require large containments and reservoirs of cooling water that weigh as much ore more than the reactor, which have to be arranged for gravity feed (for fail safe reasons). Even if you took the hit of carting around the cooling water on top of an oversize locomotive, your first derailment would totally invalidate your passive cooling doctrine.

"I already accounted probable public dislike for the idea in my conditionals. It is a "soft objection" in that we do plenty of things far more dangerous every day in our society, however they have better PR."

Risk and cost aren't the same thing. We do a lot of stuff daily, like mine and burn coal, that have roughly calculable human and environmental costs, because we have plenty of experience with it. And through experience we know the risk of paying those costs is unity. The cost of a nuclear meltdown is literally incalculable, because all meltdowns are different, as are public and private reactions to them. The statistical universe isn't large enough (yet). But we do know that the risk of at least one meltdown in a given century is, as far as we know unity, because we've had two in the last 25 years.

"As to the mass situation it is really not necessarily a good one. The Submarine also has to deal with water resistance. A V8 engine that gets 15 miles a gallon in a Pickup truck might be lucky to get 2 miles per gallon in a similar mass boat.

You would have to look at the specifics of the reactor you wanted to use as well as the requirements of the train."


It actually depends on whether you can make a power reactor that generates only a few thousand horsepower, and then fit it in a railroad locomotive form factor.

Jim Baerg said...

If we didn't already have the very practical technology of overhead power lines for electric railways, I would go for nuclear locomotives. However, the combination of stationary nuclear reactors with electric railways is far more practical.

Tony "The cost of a nuclear meltdown is literally incalculable"

We have had the worst possible nuclear reactor accident at Chernobyl. The result was several dozen direct deaths & at most a few thousand cancer deaths (depending on your assumptions about the effect of low level radiation). Trivial compared to the harm from coal burning.

Anonymous said...

=Milo=



SA Phil:

"Nuke/electric trains would be effecitive, assuming you had a colony that needed that kind of capacity."

You are unlikely to have a nuclear plant onboard a train. More likely is electric cables suspended along the tracks which the train draws power from, like with many trams.



Tony:

"Fukushima Daiichi was a static site and was hardened against every conceivable natural and manmade disaster. They didn't concieve of everything."

And even though it was hit by a disaster vastly larger than anyone had planned for, they still managed (with some effort) to retain control of it, and the total incidence of health consequences from radiation poisoning from this incident is zero. Considering that the tsunami was a serious catastrophe that killed numerous people and caused incredible damage, the Fukushima reactors have clearly held up better than the rest of Japan.



SA Phil:

"An inert nuclear weapon is potentialy more dangerous than a well designed nuclear reactor."

Only if someone is malicious enough to deliberately arm it. It is highly, highly unlikely to go off accidentally. (Never say never, but it's about as close as it can get.)

Thucydides said...

Using nuclear reactors in locomotives is crazy. It isn't the reactor itself which is the problem in terms of power/weight, but the conversion machinery.

Even very small Thorium salt reactor proposals are outweighed by the network of plumbing needed to raise steam and generate mechanical or electrical energy. Very small reactors can be efficient and lightweight if you are only interested in the thermal energy with no other conversion steps, this is a NERVA engine, which is of limited use to railway engineers ;)

And of course mobile nuclear reactors are involved in accidents at a far greater rate than civil reactors are involved in melt downs and accidents, the sea floor is littered with two American and several Russian nuclear reactors from sunken submarines, and at least one Russian liquid metal reactor is "frozen" at the dock (or wherever they eventually disposed of it) when the crew allowed the operating temperature to drop below the point the metal coolant solidified. I'm pretty sure this sort of calculation has dampened any enthusiasm for nuclear powered container ships or supertankers, despite any theoretical economic advantages they might have.

Anonymous said...

Very small reactors can be efficient and lightweight if you are only interested in the thermal energy with no other conversion steps, this is a NERVA engine, which is of limited use to railway engineers ;)

=========

A reciprocating steam engine is just a steam rocket that captures the mechanical energy for use to turn a wheel.

So I "limited use" isn't really true.

As long as the reactor and the associated equipment can have a rough parity with a diesel engine and associated equipemnt (including fuel) it could be made to work.

Sure the idea of using it may or may not make sense -- but it could be made to work from a "can it be made to go" standpoint.

If you could make a Nucelar airplane and Nuclear Thermal lift vehicles are possible it can definitely be done on a train.

As for Nuke Electric - it should also be possible. The problem with Nuke Electric spacecraft thrust wouldnt exist - since you have friction availible.

(SA Phil)

Anonymous said...

Tony,

Risk and cost aren't the same thing. We do a lot of stuff daily, like mine and burn coal, that have roughly calculable human and environmental costs, because we have plenty of experience with it. And through experience we know the risk of paying those costs is unity. The cost of a nuclear meltdown is literally incalculable, because all meltdowns are different, as are public and private reactions to them.
--------------

Coal is a good one. ~4000 people die every year due to coal.

So in the last 50 years of peaceful nuclear energy use, roughly 6 times as many people have died because of coal. That Includes Chernobyl.



(SA Phil)

Tony said...

Milo:

"And even though it was hit by a disaster vastly larger than anyone had planned for, they still managed (with some effort) to retain control of it, and the total incidence of health consequences from radiation poisoning from this incident is zero. Considering that the tsunami was a serious catastrophe that killed numerous people and caused incredible damage, the Fukushima reactors have clearly held up better than the rest of Japan."

SA Phil:

"Coal is a good one. ~4000 people die every year due to coal.

So in the last 50 years of peaceful nuclear energy use, roughly 6 times as many people have died because of coal. That Includes Chernobyl."


"We have had the worst possible nuclear reactor accident at Chernobyl. The result was several dozen direct deaths & at most a few thousand cancer deaths (depending on your assumptions about the effect of low level radiation). Trivial compared to the harm from coal burning."

Cost isn't just figured in human lives. In fact, given certain accounting assumptions, human lives are almost meaningless. Now, I wouldn't go that far, but a money value can be placed on a human life. And doing so, the number of lives lost to nuclear meltdowns is almost certainly marginal to the loss of productivity for decades of a large portion of the Eastern Ukraine, and the loss of a large portion of a Japanese province for who knows how long, the loss to Japanese coastal fisheries of unknown scope for an unknown length of time, and the opportunity cost of mitigating the damage. Coal is expensive in human and environmental terms, but I'm not at all convinced it's quite that expensive.

Tony said...

SA Phil:

"A reciprocating steam engine is just a steam rocket that captures the mechanical energy for use to turn a wheel."

No it's not. It runs at a totally different pressure and temperature. It also recovers and reuses its working fluid, rather than tossing it away as a reaction mass.

"If you could make a Nucelar airplane and Nuclear Thermal lift vehicles are possible it can definitely be done on a train."

Non sequitur. Rockets and jet engines are highly sophisticated artifacts, but they're ultimately simpler in operation than power generating rigs. They really are two entirely different technologies.

Anonymous said...

Tony,

No it's not. It runs at a totally different pressure and temperature. It also recovers and reuses its working fluid, rather than tossing it away as a reaction mass.

======

What is the pressure and temperature of my nebulous steam jet/rocket?


Or my nebulous steam piston?


Yes, I was counting on saving reaction mass to compensate for the added machinery of the piston.


(SA Phil)

Anonymous said...

(SA Phil)

A Diesel Piston engine isnt all that disimilar to a jet engine either.

It uses Air as reaction mass, heated and expanded by the combustion of the fuel to drive the piston.

Its just an Air Pump.

A jet is just pumped air.

Tony said...

"What is the pressure and temperature of my nebulous steam jet/rocket?"

Relatively low pressure rockets run at about 40 bar and 2500 F.

"Or my nebulous steam piston?"

You'd do better with a superheated steam turbine, which runs at a whopping 270 bar, but only about 1100 F.

NB: the high pressures in steam turbine technology are the result of a closed cycle and a high equipment mass. An open cycle steam plant as light as a rocket or jet engine, running at only 1000-1200 F would have a very low operating pressure and consequently low thrust.

Anonymous said...

(SA Phil)

That one flew right over your head.

How is it you get to decide the parameters of the steam rocket that I was comparing the steam piston to? I was speaking in the abstract.


Some alternative parameters -->

A steam rocket is any steam exhaust source that produces steam at a measurable pressure.

A steam piston is any piston that I can move with steam.

Tony said...

SA Phil:

"A Diesel Piston engine isnt all that disimilar to a jet engine either.

It uses Air as reaction mass, heated and expanded by the combustion of the fuel to drive the piston.

Its just an Air Pump.

A jet is just pumped air."


Quibble: the reaction mass in air breathing, fossil fuel engines is actually a mixture of combustion products and air.

Much more important and to the point, a diesel engine does work through a mechanical or electrical transmission, driving some kind of machine in frictional contact with an external medium (e.g. rails/roads/water). A reaction engine (air-breathing jet or liquid/solid/nulear/electric rocket) does work by directly expelling exhaust products and/or a non-burning reaction mass at high temperature. I really don't see that much in common, except at a highly conceptual and not very practical level.

Anonymous said...

(SA Phil)

Air is the largest part by far. Diesels usually run air fuel mixes from 20:1 to 100:1.

-----
The comparison I was making was on the conceptual level.

Thus the fact they are similar on a conceptual level was the point.

If you think that is a useless comparison. Oh well. What else is new?

Tony said...

SA Phil:

"That one flew right over your head.

How is it you get to decide the parameters of the steam rocket that I was comparing the steam piston to? I was speaking in the abstract.

Some alternative parameters -->

A steam rocket is any steam exhaust source that produces steam at a measurable pressure.

A steam piston is any piston that I can move with steam.

Air is the largest part by far. Diesels usually run air fuel mixes from 20:1 to 100:1.

-----
The comparison I was making was on the conceptual level.

Thus the fact they are similar on a conceptual level was the point.

If you think that is a useless comparison. Oh well. What else is new?"


I didn't miss anything. I'm just aware that as an engineer one is not allowed to select arbitrary parameters and assume that a machine can be made to perform to them. Engines that work against a medium through mechanical transmissions are not in the same realm as reaction engines. The fact that examples of each can use air as an oxidizer for fuel combustion and for moving mechanical parts is irrelevant and even misleading. For example, a diesel engine is manifestly not an air pump. When the air leaves the cylinder, it ceases to do work. The work is done by generated electricity or a mechanically driven wheel of some type.

Thucydides said...

Diesel engines are also dissimilar to jet engines on a very fundamental level: Diesel engines use the Diesel cycle to generate power from combustion, while jet engines (even ones attached to mechanical transmissions) use the Brayton cycle.

Different thermodynamic cycles provide far different outcomes, even if you are using the same fuel (JP-8 can burn in a diesel engine, or both jets and diesels can run on Kerosine), or even similar mechanical innards. Just compare various factors like thermodynamic efficiency, power/weight ratios or throttle response between a Diesel engine, a Stirling engine and a reciprocating steam engine all using JP-8 as fuel and sized for the same power output.

Quick comparisons can be made between marine diesels and the Kockums Stirling units installed in some Swedish submarines, and triple expansion steam engines with similar power outputs powered ships until the 1950's if you want to look at hard numbers.

Tony said...

I wasn't quite complete when I said air in a piston engine's exhaust doesn't do any work. You can use it to spin a turbocharger or power an engine brake. But those aren't required to make the engine function.

Anonymous said...

Tony,

For example, a diesel engine is manifestly not an air pump.

=========
Wow there are a lot of Engine designers who would be surprised to hear this!

Since that is what it is often referred to .. in Engine development.

(SA Phil)

Anonymous said...

Diesel engines are also dissimilar to jet engines on a very fundamental level: Diesel engines use the Diesel cycle to generate power from combustion, while jet engines (even ones attached to mechanical transmissions) use the Brayton cycle.

==========

They both are using expanding air. Air that is expanded by combustion.

I have not once gone beyond pushing of a piston or air out the back of the jet.

The rest is being added for some unknown reason just for argument's sake.

(SA Phil)

Tony said...

SA Phil:

"Wow there are a lot of Engine designers who would be surprised to hear this!

Since that is what it is often referred to .. in Engine development."


Then I would have to say, wow, there are a lot of automotive engineers who are incredibly sloppy in their terminology. I mean, I can see that at the the most basic level an internal combustion engine moves a fluid just like any pump. But the purpose is entirely different. When a fluid leaves a canonical pump (of whatever design) it is considered to have further use, otherwise you wouldn't use a pump to move it. In a piston engine the whole point is to create rotary motion for subsequent use by an electrical generator or a drive train. The movement of air through the engine is not a component of the engine's purpose. If you showed me a diesel engine and told me to point at the air pump, I'd point at the blower, not the cylinders.

"They both are using expanding air. Air that is expanded by combustion.

I have not once gone beyond pushing of a piston or air out the back of the jet.

The rest is being added for some unknown reason just for argument's sake."


The reason is known, and it's not for the sake of argument. The reason is establishing a sense of clarity about what is happening. Rotary motion in a piston engine is not the same thing as thrust in a reaction engine.

Anonymous said...

Tony,

The reason is known, and it's not for the sake of argument. The reason is establishing a sense of clarity about what is happening. Rotary motion in a piston engine is not the same thing as thrust in a reaction engine.

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

So basically you take my statement, decide for yourself on the context of my statement, and *then* explain to me why I am wrong.

Another Strawman.

-------
I explained my actual context and was ignored.

(SA Phil)

Tony said...

SA Phil:

"So basically you take my statement, decide for yourself on the context of my statement, and *then* explain to me why I am wrong.

Another Strawman.

-------
I explained my actual context and was ignored."


As near as I can tell, your context was that a steam engine was a captured rocket. Since I don't believe that for one second, your context is invalid to me, and apparently Thucydides as well.

A steam engine moves a heated fluid from hear to there and extracts rotary motion out of it at some point. A rocket releases heated fluid and extracts work directly from the release. They are similar in that they use heated fluids, but they are not the same kind of machine. That's the context that I see, and it applies equally well to the forced comparison between jet engines and diesels.

Anonymous said...

Tony,

A steam engine moves a heated fluid from hear to there and extracts rotary motion out of it at some point. A rocket releases heated fluid and extracts work directly from the release
----------------------

===========

The work done by the expanding air in the piston engine is done to the piston. The expanding air pushes it.

The work done by the expanding air in the rocket is done out the back of the rocket.

Its still just action/reaction Newtonian physics.

It doesnt diverge until the piston transfers mechanical energy to the crankshaft.

(SA Phil)

Tony said...

SA Phil:

"The work done by the expanding air in the piston engine is done to the piston. The expanding air pushes it.

The work done by the expanding air in the rocket is done out the back of the rocket.

Its still just action/reaction Newtonian physics.

It doesnt diverge until the piston transfers mechanical energy to the crankshaft."


Jeepers! Any engine that relies on combustion is the same engine if you look at it like that. It's reductio ad absurdum to go that far. But if you look at engines as a power producing unit, the difference is elementary -- one produced thrust from exhaust gasses while the other produces rotary motion and exhaust gasses with no signifcant power.

Anonymous said...

Tony,

Jeepers! Any engine that relies on combustion is the same engine if you look at it like that. It's reductio ad absurdum to go that far.
===========

If you say so. your label doesnt change anything though.

=========
one produced thrust from exhaust gasses while the other produces rotary motion and exhaust gasses with no signifcant power.
==========

They both produced thrust from exhaust gasses.

In the piston engine the thrust was applied to the piston. Without that thrust there is no rotary motion.

The Exhaust gasses that leave the piston engine have been robbed of much of their energy.


(SA Phil)

Tony said...

SA Phil:

"If you say so. your label doesnt change anything though."

I was simply stating a fact, not applying a "label".

"They both produced thrust from exhaust gasses."

Exhaust gasses leaving the engine produce thrust? You want to try that on for size with the engine designers at your day job?

"In the piston engine the thrust was applied to the piston. Without that thrust there is no rotary motion."

Inside the piston, during the power stroke, the gasses aren't exhaust.

"The Exhaust gasses that leave the piston engine have been robbed of much of their energy."

That's why they don't contribute to power the way gasses leaving a turbojet do. But, to reiterate, when they're actually producing power, they're not exhaust.

Anonymous said...

I wish I hadn't brought up locomotives in space...so what other vehicles would we have on other worlds; like Luna, Callisto, Mars, or Titan. Besides next gen moonbuggies and those surface skimming transports, is there any other vehicles? I know that there is the possibilities of airplanes and airships on Mars, but would we need boats on Titan? or even submarines?

Ferrell

Anonymous said...

=Milo=


Ferrell:

"I know that there is the possibilities of airplanes and airships on Mars, but would we need boats on Titan? or even submarines?"

Titan has bodies of liquid. Therefore there is a potential use for liquidgoing vehicles. There will probably exist overland routes between most locations as well, but we know from Earth's example that people will often prefer going by sea even when a land route is available, and that even lakes and rivers can be worth building ferries on. If there are more than a handful of people on Titan, they will find some use for boating.

Furthermore there is one important application that will need submarines: namely, scientific research. There is the potential for a lot of interesting stuff under Titan's waves, and the only way we'll be finding out about it is to send a vehicle that can get there. (A robotic probe will do.)

Thucydides said...

Ferrell

Submarines will be useful on (or under) Europa. Most types of mechanical traction used on Earth should be usable on the surface of other planets or moons with suitable materials/modifications to account for local conditions. The Moon rover isn't too different from a dune buggy on Earth (substituting batteries and an electric motor for the VW flat 4 is perhaps the biggest difference at the highest level, and of course a VW "Bug" isn't built of aerospace materials by an aerospace contractor), and similar vehicles could work on almost any low gravity world.

Any world with an atmosphere can support aerostats or aerodynes designed for the local gravity and gas pressure, or allow aerocapture and aerobraking of incoming spacecraft.

On a more speculative level, if conditions are very different from Earth, then different solutions will have to be arrived at. Planets with or embedded in strong magnetic fields might be able to take advantage of electromagnetic induction, as a possible advantage.

WRT the great engine debate going on upthread, yes on a trivial level all heat engines work through the expansion of gas, but the different thermodynamic cycles extract the energy in different manners, giving different results. While you can use JP-8 to power a boiler, there are no aircraft powered by triple expansion steam engines turning propellers, few diesel powered aircraft but plenty of turboprops (comparing apples to apples). There are very good reasons for this...

Anonymous said...

Tony,

Exhaust gasses leaving the engine produce thrust? You want to try that on for size with the engine designers at your day job?

Inside the piston, during the power stroke, the gasses aren't exhaust.

-----------

The difference you are harping on here is semantics

The expanding gasses inside the piston are no different from the expanding gasses leaving the rocket.

If you call them "exhaust" or not its a meaningless label at that point.

They *are* "exhaust gasses" visavis a direct comparison with a jet/rocket.

Keep in mind, I did not anywhere say the exhaust gasses *leaving the piston engine* produce thrust. You said that I said that so that you could sound all incredulous.

(SA Phil)

Anonymous said...

WRT the great engine debate going on upthread, yes on a trivial level all heat engines work through the expansion of gas, but the different thermodynamic cycles extract the energy in different manners, giving different results. While you can use JP-8 to power a boiler, there are no aircraft powered by triple expansion steam engines turning propellers, few diesel powered aircraft but plenty of turboprops (comparing apples to apples). There are very good reasons for this...

==========
Please note I did not say they all have similar types of performance.

I only ever meant that the principle used to push the piston is the principle used to push the rocket.

jollyreaper said...

Random thought: Windows 8.

http://tech.slashdot.org/story/11/06/02/0437233/Windows-8-Previewed-At-D9

Gets into our talk of prognostication. I don't think anyone here will argue that the mouse and keyboard are the be-all and end-all of computer interfaces. It's certainly possible that a better idea is out there just waiting to be invented. We've been waiting for it for decades. We may have several more decades to wait.

The GUI we've grown used to might have room for improvement but everything we've seen as improvements offer more drawbacks than benefits. It's truly a bloody mess.

Certainly we haven't seen the cyberdecks that might have seemed like a reasonable prognostication for 2011 back from the early 80's. The hard drives are bigger, the graphics prettier, but they're still doing the same old thing. As far as businesses go, I haven't really seen a true need for an upgrade since the late 90's. Certainly the software is getting bloatier and slower but there's been nothing since the arrival of the Internet in broad use that screams out "Dude, you need to upgrade." Windows 2000 and Office 2000 were pretty much all anyone needed and anything new added in the later versions of Office could have just as easily been done on the older systems.

The only real need to upgrade from late 90's systems is about multimedia and gaming -- compelling arguments for marketing perhaps but not for the average secretary worker bee. I couldn't run HD video on my 1999 rig. Going past 65k rows in Excel is nice but I question whether they couldn't have added that feature long ago.

I'm still waiting for the next big thing that makes me take back those words, something so clearly superior in the business world that I'd be happy to chuck the Win2K box in the dumpster and embrace the new shiny.

This isn't quite the Decellerando but maybe approaching the feature per horsepower asymptote? 2011 machine is x times more powerful than 1999 machine but the typical software is pretty much doing the same old crap, we're not seeing productivity gains to match the power.

(Again, I'm talking for business use. I game and watch HD video on the computer under my telly. Couldn't do HD anything with my 1999 machine and certainly not modern games. But those aren't business apps.)

Tony said...

SA Phil:

"The difference you are harping on here is semantics...

Keep in mind, I did not anywhere say the exhaust gasses *leaving the piston engine* produce thrust. You said that I said that so that you could sound all incredulous."


No, I was comparing apples to apples, which you were not. During a piston engine power stroke, the expanding gas is not exhaust. It's a working fluid. The work is done during combustion.

In a jet engine, all of the work is done post combustion, both in spinning the turbine that powers the compressor and in producing thrust.

Whatever claims you wish to make, that's not a semantic difference in objective analysis of the power cycles.

Tony said...

jollyreaper:

"This isn't quite the Decellerando but maybe approaching the feature per horsepower asymptote? 2011 machine is x times more powerful than 1999 machine but the typical software is pretty much doing the same old crap, we're not seeing productivity gains to match the power."

It's doing the same old stuff, but more of it per second. Wearing my database administrator hat, I can tell you that we routinely process SQL scipts in milliseconds that would have taken seconds or even minutes ten years ago. The rise of the data-driven, content-rich sites that are everywhere today is a direct consequence of improved computing power, no matter how mundane the interface might seem.

Look at the standard business application interface a few years ago. It had 10-20 text entry fields and drop down boxes, plus four or five buttons. Today, with internet technology and quicker raw data processing, we moved the business interface off of the clerk's desktop and onto the customer's personal computer, and with a richer, more interactive experience.

Anonymous said...

Tony,

The work is done during combustion

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

Nope -

The combustion occurs, the gasses expand, they push the piston.

The work is still done "post combustion"

Because the kinetic energy is a result of the combusition. Not a parallel process to it.

You can literally measure the time it takes inside the cylynder with the right equipment.


(SA Phil)

Tony said...

SA Phil:

"Nope -

The combustion occurs, the gasses expand, they push the piston.

The work is still done "post combustion"

Because the kinetic energy is a result of the combusition. Not a parallel process to it.

You can literally measure the time it takes inside the cylynder with the right equipment."


You're correct -- as far as you go. But the heated gas still does no work exiting the engine. In fact, you can make a case that it exerts a parasitic drag on engine output power as the exhaust is pushed out of the cylinder during the exhaust storke. Aside from waste heat (which exists in all heat engines) the gasses in a jet only do work after combustion, either in driving the turbine or producing thrust.

In any case, the point I was making is that you really have to make comparisons of work at similar points in the process. IOW, what does X do at Point Y. In a turbojet, at the point you measure engine power output, you are measuring reactive thrust. In a piston engine, at the point of engine power output, you are measuring rotational energy.

Anonymous said...

Tony,

You're correct -- as far as you go. But the heated gas still does no work exiting the engine. In fact, you can make a case that it exerts a parasitic drag on engine output power as the exhaust is pushed out of the cylinder during the exhaust storke.

---------

Sure - this is true.

I was comparing what happens in the cylinder to the rocket only.

Basically that it is the same principle - utilizing the kinetic energy of expanding gasses.

The rest I believe was a mis-explanation/misunderstanding of what I meant.

(SA Phil)

Tony said...

SA Phil:

"I was comparing what happens in the cylinder to the rocket only.

Basically that it is the same principle - utilizing the kinetic energy of expanding gasses.

The rest I believe was a mis-explanation/misunderstanding of what I meant."


Now that makes more sense to me.

Entre nous, I would have made the point something like this:

You can think of a jet or rocket engine as a piston not confined by a cylinder.

Jim Baerg said...

Re: vehicles on Titan

The thick atmosphere will make air transport much more practical than on Earth. The pressure is about 1.5earth atmospheres & that combined with the low temperature makes the density over 4 times earth's atmosphere. So airships would carry 4 times the cargo for a given volume of lifting gas. The lifting gas would be hydrogen since there is no ambient oxygen to support combustion.

Heavier than air flight would also be much easier. Apparently the thick air & low gravity mean strap-on wings would allow human powered flight. However, I wonder how clumsy the insulating suit would have to be.

Anonymous said...

=Milo=


Jim Baerg:

"So airships would carry 4 times the cargo for a given volume of lifting gas."

Umm, wouldn't the airships also be under high pressure and low temperature? Unless they're hot air balloons, of course.

Jim Baerg said...

Yes. The hydrogen in the airship would be at 1.5 atm pressure & a bit under 100 K temperature. So there would be more hydrogen per unit volume of airship. The saving would be in the amount of structural material for the airship to carry a given amount of cargo.

Heavier that air vehicles might still be the better way to go. It depends on how strong & gusty the winds are on Titan. The greater vulnerablity of LTA craft to turbulence is a major problem for them on earth.

Anonymous said...

Hmm...helicopters on Titan; they would work at least as well as on Earth, they have relatively long range compared to trucks or crawlers, can get to many areas unreachable by other means, also they could be used for rescue of explorers. Actually, pretty much any vehicle that would work on Earth, (with suitable modifications), would work on Titan. That should simplify designs for Titan vehicles somewhat.

Ferrell

Tony said...

Helicopters on Titan should get more lift than on Earth, because the atmosphere has a pressure of 1.5 bar at the surface. Of course, they'd fly slower due to increased drag...

Thucydides said...

By the time we actually get to Titan, we may have totally different ideas about what constitutes effective travel arrangements.

Moravec rotating tethers picking up and dropping payloads on the surface might make sense if most of the human activity is in space among the Saturnian moons rather than on the surface, since the main thrust of any activity on the surface would be to get to and from orbit, to use a somewhat improbable example.

Anonymous said...

(SA Phil)

Youd need to cart around Oxygen for all these Titan vehicles, or else use some other type of engine.

Anonymous said...

SA Phil said:"Youd need to cart around Oxygen for all these Titan vehicles, or else use some other type of engine."

If you have people on board, you'd need to carry oxygen anyway; plus, you can get(literally) water from rocks on Titan, hence oxygen. Living, and getting around on, Titan might be easier than getting there.

Ferrell

Anonymous said...

(SA Phil)

Actually you'd need a lot of oxygen though

For example a gasoline car engine is basically set up to run 14:1 A/F

20% of the 14 is oxygen so you would need over twice the oxygen that you would fossil fuel in a Earth like vehicle operating in an atmosphere that lacked oxygen.

Perhaps you could do with a bit less, but it still would probably change your design parameters some. A lot more Tankage required than on Earth.

Jim Baerg said...

BTW Airships on Titan would have further advantage over Airships on Earth.

The low temperature means that the nitrogen & methane in the air will liquify under a litte extra pressure, so a Titan airship can change its buoyancy by pumping air into a lightweight ballast tank.

Thucydides said...

I would hope that we are using fuel cells or some related technology to drive vehicles by the time we get to Titan.

No moving parts and high levels of efficiency in converting the chemical energy of the fuel to electrical energy are quite desirable attributes of conversion systems in any setting, and Solid Oxide Fuel Cells (SOFC's) can directly use hydrocarbon fuels. Once that technology matures I think it will start displacing IC engines in many applications.

Tony said...

If you're using fuel cells or IC, wherever you get your oxidizer, the real power source is defined by how you get your electricity. The oxidizer is just a means of storing energy, to be liberated when the oxidizer is reacted with the fuel. (The fuel is also an energy storage medium in fuel cells -- just as it is on Earth.)

WRT, tethers or other means to get on and off the surface, those are orthogonal to the problem of actually getting around on the surface once you are there.

Anonymous said...

=Milo=



Ferrell:

"plus, you can get (literally) water from rocks on Titan, hence oxygen."

There's oxygen in the rocks, but you need to split it, which costs a lot of energy. If you have something that can generate that energy it'd make more sense to use it for propulsion directly. Unless you're manufacturing the oxygen in stationary bases and carrying the final product.

Atomically speaking oxygen is cheap to get, everywhere. (On worlds where rocks aren't made of dihydrogen monoxide, they're largely made of silicon dioxide.) The problem is how you're planning to carry it in your vehicle.

Anonymous said...

Tony,

If you're using fuel cells or IC, wherever you get your oxidizer, the real power source is defined by how you get your electricity.
=========

Not in this case? - since they were talking about vehicles operating in an atmosphere.

An IC engine wouldnt need much electricity for motive power in that scenario. (A gasoline ignition/injection system is about a 25 watt draw, Diesel unit injector solinoids are around 100 watts). A simple Alternator works there.

(SA Phil)

Anonymous said...

(SA Phil)

How omnipresent is the Methane in Titan's atmosphere?

For example is it like oxygen or Carbon Dioxide in our atmosphere?

If it is you could make an Internal combustion engine that carried no fuel at all, Only Oxygen. It could mix the oxygen into the atmophere it sucked in from outside and then burn the ambient mehtane that way.

Anonymous said...

SA Phil: the methane in Titan's atmosphere is closer to 70% to 90%, if I remember correctly. A 9% methane to air mix will burn, here on Earth; I'm not sure what the correct mix would be on Titan...

Anyway, even if you use electric vehicles to get around, you still need a powerplant to charge the things, and a methane-fired plant would be a natural on Titan.

Ferrell

Thucydides said...

An IC engine turning a mechanical transmission like a conventional car or truck on Earth will use a very small fraction of the energy to actually turn the wheels (up to 66% of the fuel energy is blown out the exhaust or the radiator). Adding a generator that then powers electric engines in the wheels instead of a mechanical transmission adds conversion steps and more losses. A fuel cell converts the chemical energy of the fuel to electrical energy in one step (and usually at very high efficiencies like 60% or more) which can then go straight to the electric motors and other systems. The end result is a vehicle which can go two or three times as far using the same amount of fuel.

SOFC's can use hydrocarbons directly as fuel, and atmospheric oxygen as the oxidizer here on Earth, one rigged to run on Titan might draw atmospheric methane from a vent and add LOX from an on board source to power the vehicle.

While a tether might be orthogonal to the idea of moving on the surface, a space based civilization might view the idea of surface transport as anachronistic to their needs. One thing which has come up in the past on these boards is we often try to apply 20th and 21rst century tropes to the PMF (or even the implausible mid future); the future is the same, only more so.

I'm just trying to see what is possible outside the box.

Anonymous said...

=Milo=



Ferrell:

"A 9% methane to air mix will burn, here on Earth; I'm not sure what the correct mix would be on Titan..."

Keep in mind that you most likely wouldn't be using pure-methane-to-Earth-air, but rather Titan-air-to-pure-oxygen. Titan's atmosphere is 1.4% methane and 98.4% nitrogen, which is below your 9% mix even before adding oxygen, but now you can add a larger amount of oxygen than Earth's atmosphere has to make up for that.


"Anyway, even if you use electric vehicles to get around, you still need a powerplant to charge the things, and a methane-fired plant would be a natural on Titan."

Not unless you have a source of oxygen. If you need to make your own oxygen by splitting rocks, then methane-oxygen combustion is only a power storage mechanism, not a power source, and so useless for a power plant.

Power plants will most likely be nuclear (fission or fusion). Solar just doesn't work well this far out, even before accounting for the haze.



Thucydides:

"While a tether might be orthogonal to the idea of moving on the surface, a space based civilization might view the idea of surface transport as anachronistic to their needs."

Unless space travel is very cheap, people will try to move around without it when they just need to go somewhere else on the same world.

Unless all human presence on a world is limited to a small region, in which case people might simply not care much about travelling to the rest of the planet (but on the rare occasions that they do need to go there, they'll prefer to travel by surface if they can).

Note that newly started colonies are more likely to be limited to a small region (people will only start spreading out when they've used the area they have to its limit) while research outposts are less likely to be such (scientists will probably want to study a variety of locales to get a better picture, and will spend a lot of their time doing field work).

But for the most part using space travel to move across a planet/moon feels like using a jumbo jet to travel to another location in the same city.

Jim Baerg said...

SA Phil
How much methane in Titan's atmosphere.

It looks rather marginal for running combustion engines. About 1.6% combustible gasses.

http://en.wikipedia.org/wiki/Atmosphere_of_Titan#Composition

Tony said...

SA Phil

"Not in this case? - since they were talking about vehicles operating in an atmosphere.

An IC engine wouldnt need much electricity for motive power in that scenario. (A gasoline ignition/injection system is about a 25 watt draw, Diesel unit injector solinoids are around 100 watts). A simple Alternator works there."


On Titan, you have to separate the oxygen from water or some other oxide before you can use it in an IC engine. So, in fuel cycle terms, the oxygen is really just a storage medium for a portion of the electrical energy used to separate it.

The so-called "hydrogen economy" has the same problem, BTW. Since there's no free hydrogen in the Earth's atmosphere, the fuel cycle relies on electrical power for electroysis of hydrogent from water. The hydrogen itself is just an energy storage medium.

Tony said...

Thucydides:

"While a tether might be orthogonal to the idea of moving on the surface, a space based civilization might view the idea of surface transport as anachronistic to their needs. One thing which has come up in the past on these boards is we often try to apply 20th and 21rst century tropes to the PMF (or even the implausible mid future); the future is the same, only more so.

I'm just trying to see what is possible outside the box."


That's fully appreciated, but sometimes there simply is no outside to the box. A rotating tether is a megastructure, even on the scale of a moon like Titan. It can only be brought into synchronization with a few spots on the surface of the staellite, and then only at or close to the equator. (For convenience's sake -- you could work out different orbits and different conincidence points, but it would be an exercise in celestial gymanastics far more complex.) Anyplace else you want to go on the body, you have to find a different means.

Anonymous said...

(SA Phil)

It might be possible that ~1.4-1.6% could work with sufficient pressure.

Might be hard to get a dynamic range like you see in most current IC engines but we have run engines in vehicles pegged at over 100:1 A/F during testing.

Maybe it could "cruise" (light engine load) on the atmospheric methane, and then used stored methane to accelerate (higher engine load)

=======

Would it take more power to crack the oxygen then you would get from burning the Methane in an IC engine?

If it would then IC engines (or fuel cells) would be used for mobile sources only - basically as has been mentioned.

However if you can make the oxygen and burn the mehtane and come out ahead somehow, you could use a combusion engine as your power plant also.

Tony said...

SA Phil:

"However if you can make the oxygen and burn the mehtane and come out ahead somehow, you could use a combusion engine as your power plant also."

The Gods of Thermodynamics respond with a resounding "NO!". Taking oxygen (or anyo ther chemical) out of a given compound in an environment costs you energy to push it "uphill" away from the prevailing chemical equilibrium in that environment. You always spend more energy doing that than you can extract from the oxygen reacting with other chemicals in the environment.

The reason we get more energy out of petrochemicals that we invest in them is that the energy was already put in by the sun growing the precursor biologicals, and then by gravity in compressing them. If we had to make gasoline, diesel, or kerosene out of raw elements, we'd need an energy source first to separate the elements, and then more energy to combine them into hydrocarbons. And we'd never realize as much energy at the output end as we put in.

Anonymous said...

(SA Phil)

The Methane however is already "made"

So the question refers to the oxygen.

I have no idea where you get the oxygen from on Titan.

If I have a burnable fuel lying around then everything is how easy it is to get the oxygen.

Tony said...

SA Phil:

"The Methane however is already "made"

So the question refers to the oxygen.

I have no idea where you get the oxygen from on Titan.

If I have a burnable fuel lying around then everything is how easy it is to get the oxygen."


I understood the context. The point I'm making is that the oxygen is not freely available in the atmosphere. (In fact, no chemical that can react with other chemicals in an environment is freely available -- it reacts and forms compounds.) You have to electrolyze oxygen out of water ice (after investing energy to liquifying the ice). The energy you invest in that is more than the energy you get out of burning the oxygen with methane.

Anonymous said...

Well, obviously I was mistaken about the percentage of methane in Titan's atmosphere. Someone asked where oxygen would come from on Titan; water ice is apparently a major component of rocks there, much like fieldspar is here on Earth. Water would be a very valuable produce on Titan and so well worth the cost of mining and cracking...while methane powered vehicles should be practical for surfave travel on Titan, large scale methane-fired powerplants would only be used for secondary or emergency power. I guess that I either didn't make myself clear, or let my enthusiasm get the better of me. :*

Ferrell

Anonymous said...

(SA Phil)

Everything seems to come back to some sort of nuclear power (fission or fusion)

Since fission is so much "Easier", Fissionables do become a sort of colonization related McGuffin to any setting that doesnt have Mr Fusions.

Jim Baerg said...

Given, off Earth habitats & no fusion, I could see fissionables mined in the inner solar system being traded for volatiles from the outer solar system.

If fusion works but has a large minimum size then fission might still be used a lot for smaller power sources & neutrons from D-D fusion would be used to breed Pu239& U233 from U238 & Th232.

Anonymous said...

(SA Phil)

It looks like according to wiki its 4.9% mehtane at lower altitudes, with liquid mehtane pools (of whatever size) and rain.

It also has wind, so depending on need you could possibly do Wind Power based electricity if you are fission-phobic.

Anonymous said...

=Milo=



Tony:

"The Gods of Thermodynamics respond with a resounding "NO!". Taking oxygen (or anyo ther chemical) out of a given compound in an environment costs you energy to push it "uphill" away from the prevailing chemical equilibrium in that environment. You always spend more energy doing that than you can extract from the oxygen reacting with other chemicals in the environment."

I'm not 100% sure of this. The reaction SA Phil is proposing is, in effect,
2*H2O + CH4 -> 3*H2 + CO2
(Sorry about ugly formatting, Blogger doesn't allow subscripts.)
I don't know if that reaction is exothermic or endothermic (if it's endothermic, then it most likely won't work at all since your oxygen will prefer to bond back with the hydrogen rather than the carbon), but it would at least require someone actually familiar with chemistry to determine - it's not obvious at a glance that it wouldn't work, as would be the case if the left and right sides were identical.

Nevermind that, I'll try to read up on chemical thermodynamics myself and see if I can do the math.
Apparantly the quantities we need are called "enthalpies of formation", which are:
Water: -285.83 kJ/mol
Methane: -74.85 kJ/mol
Hydrogen: 0 kJ/mol (per definition)
Carbon dioxide: -393.51 kJ/mol
(Source.)

Our reaction then becomes
(2*-285.83 + -74.85) - (-393.51) = -253 kJ/mol
Which is endothermic, meaning that it won't work. Too bad.

Anonymous said...

Internal Combustion engines and windmills...sounds like the 1930's; except for those airtight buildings with airlocks. :) Yeah, wind-turbines would be a viable source of power for small scale outposts. Are there any potential electricity or heat producing processes that use nitrogen, ethane, methane, or any other commonly found substances on Titan that don't envolve combustion or finding deposits of fissionable ores? If not, then we need to come up with a hirarchy of power production for Titan outposts if we are going to have long term human habatats on that world.

Ferrell

Anonymous said...

=Milo=



We are going to need fusion power in order to even reach Titan before the crew dies of boredom. (Maybe fission, if your boredom tolerance bar is exremely high.) By the time we have enough traffic to establish long-term habitats, energy isn't going to be what we're worrying about.

Thucydides said...

From a PMF perspective, people might not actually be all that interested in the surface of planets.

Building a radiation shielded structure in space uses a common template that works virtually everywhere in the Solar System. Vacuum is a perfect insulator and the rotational velocity can be adjusted to whatever internal gravity you chose. Life support machinery will have the same parameters, the only real variable will be what you use as a power source and the size of your radiators.

In the inner Solar System, solar energy is pretty abundant, and in the outer Solar System, nuclear energy will work. (Actually, solar will work so long as you can build and support really huge collectors, and size won't be much of an issue in a free flying colony structure).

Planetary structures will have to contend with gravity, thermal loads, day/night cycles, atmospheres etc., and each one will be a unique engineering problem. I suppose there will always be people who won't mind such things, and there may be things you can't mine from asteroids or comets that require a dedicated surface installation. My thinking is if the majority of people in the PMF are dedicated to living and working in space, then far less attention will be paid to issues like living and working on the surface of planets and moons.

Anonymous said...

=Milo=



The ocean is a rather simple environment compared to the land (at least if you're interested in the surface rather than what's underneath). It's flat, water doesn't change temperature quickly. But most people don't live on ships. Hmm, why?

Tony said...

Milo:

"Our reaction then becomes
(2*-285.83 + -74.85) - (-393.51) = -253 kJ/mol
Which is endothermic, meaning that it won't work. Too bad."


It has to be endothermic, from basic principals. We know that electrolyzing hydrogen out of water, then reacting it with oxygen in the Earth's atmosphere is endothermic at the fuel cycle level. Burning the oxygen from electrolysis with methane from Titan's atmosphere would have to be as well.

Anonymous said...

I'm pretty sure that there are plenty of scientists, and others, who would not want to go all the way to Saturn's orbit and not land on Titan (or any of it's other moons). Anyway, whatever means of providing power to local off-world outposts are eventually used, we'll have to come up with a design fairly soon because we'll either be there in a few decades or we won't be going anywhere beyond orbit for the rest of this century, at least.

Ferrell

Anonymous said...

=Milo=



Tony:

"It has to be endothermic, from basic principals. We know that electrolyzing hydrogen out of water, then reacting it with oxygen in the Earth's atmosphere is endothermic at the fuel cycle level."

Chemically speaking, the energy change of the reaction you describe is zero, since the start and end products are identical:
2*H20 + O2 -> 2*H2 + 2*O2 -> 2*H20 + O2
(You did specify a different O2 at the end than at the beginning, not that it matters.)
In practice it would be slightly endothermic due to efficiency losses, but in theory, with a good reaction cycle, these losses could be kept pretty small.


"Burning the oxygen from electrolysis with methane from Titan's atmosphere would have to be as well."

No, the analogy would only hold if you electrolyzed water and then used the oxygen to burn the hydrogen you got from the electrolyzation. Or if you electrolyzed methane and then reattached the hydrogen to the carbon (I think that's called "reducing").

SA Phil's reaction ended putting the oxygen in a different place than it started.

Thucydides said...

Combining tropes a bit, I could see the space faring civilization setting up power satellites in orbit and using them to drive orbit to ground SSTO traffic.

Since the spaceers would be used to living and working in habs and spacecraft of various types, using a vehicle similar to a Myrabo "lightcraft" would allow them to directly access whatever place of interest they want from orbit, then take off once they are done.

Tony said...

Milo:

"In practice it would be slightly endothermic due to efficiency losses, but in theory, with a good reaction cycle, these losses could be kept pretty small."

You're missing the point. If you rely on reactants from electrolysis to power electrolysis, you'll electrolyze fewer reactants per cycle, until you just run out of reactants to generate power. And there's heat loss in every step of the process. The end products aren't "identical". There's a "+ electricity" term at the start and a "+ heat" term at the end. That means you have to input energy to crack the water into oxygen and hydrogen. Then, when you recombine them in a reaction, you get heat out and slightly less water and hydrogen than you put in.

"No, the analogy would only hold if you electrolyzed water and then used the oxygen to burn the hydrogen you got from the electrolyzation."

When you use electrolyzed hydrogen in a non-cryogenic fuel cell (as in a car), you react it with air, not stored oxygen. The oxygen is discarded or put to some other use. In the context of Titan, the oxygen from electrolysis would be used to combust with methane in the "air". The hydrogen would most likey be discarded as a waste product.

Anonymous said...

Tony: "When you use electrolyzed hydrogen in a non-cryogenic fuel cell (as in a car), you react it with air, not stored oxygen. The oxygen is discarded or put to some other use. In the context of Titan, the oxygen from electrolysis would be used to combust with methane in the "air". The hydrogen would most likey be discarded as a waste product."

Umm, no, that's not how a methane/oxygen combustion works; the products are water, CO2, and leftover methane; in an atmosphere with nitrogen there is also Nitrios Oxide compounds made as minor byproduces. Also,
"You're missing the point. If you rely on reactants from electrolysis to power electrolysis, you'll electrolyze fewer reactants per cycle, until you just run out of reactants to generate power. And there's heat loss in every step of the process. The end products aren't "identical". There's a "+ electricity" term at the start and a "+ heat" term at the end. That means you have to input energy to crack the water into oxygen and hydrogen. Then, when you recombine them in a reaction, you get heat out and slightly less water and hydrogen than you put in."
is correct, but only if you don't replenish your stock of chemicals; you're talking about a closed system, and not an open system that would more likely be used in such a setting. Since no reaction is entirely free from entropy, this whole discussion is a bit beside the point.

Anyway, just getting from point A to point B kinda defeats the purpose of exploring all the terrain between...;)

Ferrell

Tony said...

Ferrell:

"Umm, no, that's not how a methane/oxygen combustion works; the products are water, CO2, and leftover methane; in an atmosphere with nitrogen there is also Nitrios Oxide compounds made as minor byproduces."

I was talking about hydrogen from the electrolysis portion of the fuel cycle being a waste product. I wasn't even thinking about the products of combustion in an oxy-methane burn. They're irrelevant to the discussion.


"Also, [a description of the ins and outs of the fuel cycle] is correct, but only if you don't replenish your stock of chemicals; you're talking about a closed system, and not an open system that would more likely be used in such a setting. Since no reaction is entirely free from entropy, this whole discussion is a bit beside the point."

I was discussing something worse than a closed cycle. I was pointing out the physical impossibility of a self-powering cycle based on using oxidizer bound up in chemical compounds.

Anonymous said...

Tony said:"I was discussing something worse than a closed cycle. I was pointing out the physical impossibility of a self-powering cycle based on using oxidizer bound up in chemical compounds."
And this is relavant to either reality or fiction, how? I suggest that we drop this bit of round-and-round and instead move on...how about we try to come up with a concept of a Titan base instead?

I vote for inflatable modules with ice-rock domes built over them. A mission/core module, two lifesupport/crew quarter modules, two support modules, and then a seperate power plant/industrial module and another seperate module for vehicle storage and a 'native enviornment' lab. The seperate modules would be accessed by semi-buried tubes. Each module would be dropped from orbit and the aeroshells would be reused to build various storage. Your turn :)

Ferrell

Tony said...

Ferrell:

"And this is relavant to either reality or fiction, how?"

ganbatte!

Anonymous said...

=Milo=



Ferrell:

"Anyway, just getting from point A to point B kinda defeats the purpose of exploring all the terrain between...;)"

No-one said point A and point B had to be very far apart.


"I vote for inflatable modules with ice-rock domes built over them."

You have to be careful with that - human habitats are going to be artificially heated to Earthlike levels rather than Titan ambient temperature. You'd need very good insulation between your hab and the ice walls to keep them from melting.


"and another seperate module for vehicle storage and a 'native enviornment' lab"

Why not just do the "native environment" work outdoors? If you want just a little control over the environment - say, keeping Titan's atemospheric composition and temperature, but preventing wind or rain from knocking around all your testing equipment - then you can accomplish that with relatively simple makeshift constructions, which don't need to match anywhere near the stringent building codes of an airtight pressurized habitat.

Thucydides said...

If we have an established civilization in space, then so long as they have the desire to do so, they can land habs on the surface wherever they choose. Any qualified space structure should have the ability to survive surface conditions with some tweaking of the thermal control system (i.e. radiators sized for the conditions).

Anonymous said...

=Milo=



Besides a different thermal control system, you need:
- (If the space structure is designed for zero-gravity:) A firmer structure capable of bearing the walls' weight.
- (If the space structure is designed for spin-gravity:) A completely redesigned floorplan which treats the "floor" as being flat rather than a cylinder on the outer edge of the station. A torus station simply can't be landed on a planet without the majority of it being oriented completely wrong. All of it, if you don't want it to roll around.

I don't think either is necessarily very difficult, especially given the raw materials you're building the walls from are so much cheaper on a planet, rather than relying on the occasional asteroid you can catch at great expense in delta-vee.

Anything else important?

Anonymous said...

Milo said:"You have to be careful with that - human habitats are going to be artificially heated to Earthlike levels rather than Titan ambient temperature. You'd need very good insulation between your hab and the ice walls to keep them from melting."

You'd need to have them thermally insulated anyway; the domes are there to protect the inflatable manned modules from wind-blown debris and whatnot. The 'native enviornment' lab module is just an inflatable garage, not a full-habatat-type structure. Other labs or warehouses could be built from the aeroshells' parts. Besides, as someone else said in an earlier thread, the space between the dome and modules could be filled with an inert gas, like argon.

So, what's your design?

Ferrell

Tony said...

Thucydides:

Any qualified space structure should have the ability to survive surface conditions with some tweaking of the thermal control system (i.e. radiators sized for the conditions).

Sorry, but that's a non-sequitur. Unless we're talking operatic torch propulsion, spacecraft structures are going to be optimized for microgravity (or at most milligravity) and vacuum operations. They won't necessarily be structurally sound for landing accelerations or shock loads. Likewise, there's no reason that space structures would be made out of materials and/or euqipped with coatings designed to be durable in planetary atmospheres. Also, "tweaking of the thermal control system" is a non-trivial act.

Thucydides said...

I'd make the case that a qualified space hab is optimized for providing a comfortable 1 G environment for the inhabitents, which would require the ability to take acceleration stresses while hanging from a frame or tether. Since the crew needs to be protected from solar and cosmic radiation, the external shell will be made of some fairly strong and high density material to stop primary radiation, absorb any secondary radiation and maintain structural integrity in a one G environment.

For small moons, asteroids and similar environments, this might be enough to qualify. I envision power and environmental control as being a sort of "plug in" system, perhaps best pictured as umbilicals leading to the central ship/colony structure. On the surface, the umbilical can be connected to a nuclear reactor, remote power target or whatever else is desired, similarly, heat rejection will be done through off board radiators or heat exchangers.

The space civilization will be concerned with modular structures and easy to use and understand interfaces (perhaps standardized across most of the Solar System) to promote economy, saftey and ease of use.

Tony said...

Thucydides:

"I'd make the case that a qualified space hab is optimized for providing a comfortable 1 G environment for the inhabitents, which would require the ability to take acceleration stresses while hanging from a frame or tether."

You said "qualified space structure" (not "hab"). I don't know what you do for a living, but in engineering -- and technology in general -- when one say something is "qualified", one means that it has been designed, built, and tested to meet its mission requirements. There are many different potential mission requirements for space structures, even if you're just limiting the conversation to habitable ones. Designing them all to a single (ridiculously overbuilt, for most applications) standard is simply not going to happen.

For example, why armor the whole thing against radiation? Just build a storm shelter -- maybe not even in the main hab, but as a supplementary module. Why make all habitations sturdy enough for 1 g accelerations? It's not settled, but it's highly unlikely that humans need a 1 g field for long term health. It had certianly better not be the case if you want to settle the Moon and/or Mars.

In short, there's no minimum habitable space structure standard beyond holding a few psi atmospheric pressure. Everything else is negotiable, based on application.

"I envision power and environmental control as being a sort of "plug in" system..."

Now this has some merit, but no more than it already does on Earth. And we know from Earth experience that environmental systems can vary widely, depending on application, from simple residential systems set on a concrete pad next to your house, to complex integrated building systems that cost millions and have be designed into the structure as an integral system.

"The space civilization will be concerned with modular structures and easy to use and understand interfaces (perhaps standardized across most of the Solar System) to promote economy, saftey and ease of use."

But to no greater a degree than we standardize building practices to day. A stick-built house is not built like a high-rise hotel. A surface module for Titan would not be built like a hab module for orbital work.

Rick said...

Regarding habs, spin is a big unknown - health may require close to 1 g, or just enough to produce significant physiological down-ness ... or somewhere in between.

For habitation periods up to a few months (e.g., for travel), you can skimp on shielding except for a storm cellar. But for habitation over a year, GCRs rack up a substantial dosage, and you had better have substantial all-round shielding (unless a nearby planet provides it for you).

All of this said, a surface hab on (say) Titan has substantially different requirements from a space hab, and will pretty much have to be independently designed.

The same (unfortunately) goes for surface shuttles - Luna, Mars, and Titan have sufficiently different requirements that you'll need distinct vehicles. Probably Europa and Callisto, too. And needless to say, Earth.

It was a lot more convenient in the old days, when Space Patrol ships could land anywhere so long as they had enough delta v in their tanks.

Anonymous said...

=Milo=



Tony:

"For example, why armor the whole thing against radiation? Just build a storm shelter -- maybe not even in the main hab, but as a supplementary module."

How large is your hab? If you're actually trying to build a city in space, then I doubt several million people will be willing (or even able) to file in an orderly manner into the storm shelter every time a storm warning sounds. You could put a personal storm cellar into everyone's basements, but that would be highly inefficient.

Any place rated for long-term habitation by layman civilians should be designed so you don't need to take constant proactive action to keep from dying.

Plus while cosmic rays are the most intense during a solar storm, ordinary solar wind and galactic cosmic rays also need to be accounted for. That'll require some shielding.



Rick:

"Regarding habs, spin is a big unknown - health may require close to 1 g, or just enough to produce significant physiological down-ness ... or somewhere in between."

You know, one of these days we should try actually launching a donut station and see how gradually varying the spin rate affects people's health.

What would be the minimum size for a spinning habitat that doesn't make you dizzy from Coriolis effects, and how does it compare to the sizes of stuff we've already launched into space?


"All of this said, a surface hab on (say) Titan has substantially different requirements from a space hab, and will pretty much have to be independently designed."

Titan wouldn't actually need much shielding, since Saturn's magnetic field (I think) and Titan's atmosphere should do a decent job of filtering out cosmic rays. It's the Titanian atmosphere and climate that you have to watch out for.


"It was a lot more convenient in the old days, when Space Patrol ships could land anywhere so long as they had enough delta v in their tanks."

That's not completely unreasonable - if you're rated for landing on a high-gravity world, then you should be able to do just fine on a low-gravity world too. The biggest source of trouble will be landing on atmospheric versus non-atmospheric worlds (the former can use aerobraking, but also has to cope with overheating and drag, plus atmospheres can cause trouble through their different compositions and temperatures), and landing on worlds with surfaces that have trouble standing up to the heat of a rocket exhaust or the weight of a ship (such as I imagine the supposed ice surfaces of Enceladus and Europa). For stuff landing on Earth or Titan, you could also design it to splash down onto water, something that won't work anywhere else. But we still have plenty of objects that are essentially similar in nature with just slightly differing sizes.

Gas giants are entirely different. I see them as an entirely different class of object from rocky planets/moons. (I would really like a convenient term for "Rocky object large enough to be rounded by its own gravity.", so something that would include Earth, Mars, Titan, and Ceres, but not Phobos, Saturn, or Neptune.)

And of course, Venus will always be difficult to deal with, but that has nothing to do with spaceships. It's hostile even after you've landed.

Rick said...

What would be the minimum size for a spinning habitat that doesn't make you dizzy from Coriolis effects, and how does it compare to the sizes of stuff we've already launched into space?

Via Atomic Rockets, SpinCalc provides a nifty little sim, and some discussion.

But it seems that the Coriolis aspect is not really known - there have only been a few tests, obviously limited since they were in a 1 g field to start with, and coming up with different results.

Shorter answer: A spin test hab shouldn't need to be outrageously big, but we won't really know till we try it.

Tony said...

Milo:

"How large is your hab?"

In the context of the sidebar I'm engaged in with Thucydides, something small enough to land whole on a planet or satellite. IOW, not very big.

"Plus while cosmic rays are the most intense during a solar storm, ordinary solar wind and galactic cosmic rays also need to be accounted for. That'll require some shielding."

This falls under the point I was making about building for the specific application, not for some generalized set of requirements. In an interplanetary transfer hab occupied by people going one way only once in their lives, there's no reason not to rely on the storm shelter, and every economic reason to make most of the hab as light as possible.

Anonymous said...

=Milo=


I do agree that a one-way spaceship, a multi-use spaceship, and a stationary, umm, station, all have different design parameters.

In the case of a one-way spaceship I probably would design it (or at least the hab and power plant parts) to be able to land on the intended destination planet and serve as a landbound base of operations thereafter - while a structure suited for both space and surface use would obviously have more costly engineering requirements than one limited to one or the other environment, it's still lighter than carrying a separate surface-use habitat that you don't get any use of until you arrive, and the people on your one-way ship are going to need something to live in once they reach the end of their trip.

Although I suppose your "people going one way only once in their lives" doesn't imply the ship is single-use. It could be a reusable passenger liner that's just expensive enough that most people can't afford more than one trip.

Thucydides said...

Since what seems to be desired is a place to live and work after travelling to and then landing on the planet, I have something like the Mars Direct ship in the back of my mind, which is a "tuna can" with one or two levels to live in and the rest of the structure devoted to the various systems to keeping everyone alive and working in space.

Since it is launched from Earth and travels in space for several months to get to Mars, it is "qualified", but I should perhaps use different terminology. Since the example is Titan, I would guess that the Mars Direct design would still be in service with suitable updates, and instead of spinning on the end of a tether connected to the Mars insertion stage it can be attached to a framework connected to a more powerful core module to get from point a to b.

Remember my premise is most human activity will be done in space, not the planets, so it would be natural for designers to adapt space structures rather than custom building. The areoshell and engine for the Titan hab would be different than ones for Mars, but the hab itself would be largely the same.

Tony said...

By the time most people living off the Earth are living in space, There will be literally hundreds, if not thousands, of variations on the basic air-filled can. For the next several hundred (perhpas several thousand) years, living in space is going to be something you do out of justifiable necessity. That means exploring and not much else. Planets just have too much to offer to make living in space worthwhile for more than a very few, and then only on a temporary basis.

Tony said...

Milo:

"Although I suppose your "people going one way only once in their lives" doesn't imply the ship is single-use. It could be a reusable passenger liner that's just expensive enough that most people can't afford more than one trip."

Considering who is likely putting up the money, one trip, one way, from the Earth to somewhere else, will probably be free. And if the trip isn't that far -- say Earth to Mars -- there's no point in spinning or heavily shielding the passenger hab(s). They're only doing this once in their live's, for a few months, and they're not even paying (except of course with the rest of their lives on the frontier -- but who gives a crap about that?).

Rick said...

Surely two-way travel will precede one-way travel! Early exploratory missions will go, hang around for a while, then come back. At a later stage, permanent outposts will be established, with ships rotating crews in, and back home.

In this scenario, any one-way trips are quite accidental - people who die during the mission.

Yes, it is possible to make social assumptions under which deep space missions are undertaken on a one-way 'kamakaze' basis, but this probably falls into heroic/dystopian Romance rather than PMF scenarios.

In the third stage of development, some people choose to defer their return passage, signing up for repeated tours of duty.

The really challenging transitions in this type of scenario are retirement and families. Whoever (Earthside) is paying the bills is probably happy to have productive crew re-up. Retirees and kids are non-productive, but still have upkeep costs. Until these costs are low enough to be paid from savings or salaries, you can't make the jump to proto-colonization.


As for surface v space, I think that will be on a case by case basis. What is the additional cost of reaching the surface (and getting back), what is the additional cost of operating there, and how do these stack up against the costs/constraints of teleoperating from orbit?

Putting it another way, a surface base on Mars is a LOT easier than one on Venus, and not even applicable to Jupiter. (Balloons in the clouds are a whole 'nother set of tradeoffs.)

Tony said...

Rick:

"Yes, it is possible to make social assumptions under which deep space missions are undertaken on a one-way 'kamakaze' basis, but this probably falls into heroic/dystopian Romance rather than PMF scenarios."

Prior to the late 19th Century, immigrating to America or Australia was pretty much a one way proposition, except for the very richest persons. Immigrating to Mars will be even more expensive, so it will be a one way trip for everyone, except for maybe a political junket of two or three politicians once or twice a decade. I don't perceive anything particularly Romantic or heroic/dystopian in that. It's just economics.

"The really challenging transitions in this type of scenario are retirement and families. Whoever (Earthside) is paying the bills is probably happy to have productive crew re-up. Retirees and kids are non-productive, but still have upkeep costs. Until these costs are low enough to be paid from savings or salaries, you can't make the jump to proto-colonization."

IMO there won't be any real retirement -- just decreasing or altered utility for people as they get older. And families will be welcome, but only to the degree they produce useful contributors and not idle mouths. No liertarian paradise on Mars or Ceres -- only serious (small "p") puritanism and social control will keep society moving forward.

"As for surface v space, I think that will be on a case by case basis. What is the additional cost of reaching the surface (and getting back), what is the additional cost of operating there, and how do these stack up against the costs/constraints of teleoperating from orbit?"

I don't think one builds an industrial base somewhere where people won't benefit. So when you start colonizing the surface of Mars, for example, that's where the industrial base will be built. Building it in space is harder in absolute terms and removes the industry from its resource base. There's no real choice to be made.

Anonymous said...

=Milo=



Tony:

"Considering who is likely putting up the money, one trip, one way, from the Earth to somewhere else, will probably be free."

Supply and demand.

That depends on how many people want to go, and how much of an economic or scientific payoff Earth is expecting.

If the number of people interested in a one-way voyage to Mars exceeds the number of people that can fit on the ship (yes, the first number may not be very large, but the second number is also not going to be that big), then those spots will be selected based on either who is willing to pay the most, or who has demonstrated the talents necessary to be a competent pioneer, or some of both.

As long as anyone is willing to pay the price, the organization owning the ship might as well ask for one to recoup (some of?) their costs.

And why wouldn't people pay, anyway? Earth money is likely to be worthless on Mars, until such a time that travel becomes easy enough for regular trade shipments. So you might as well fork over your entire fortune, beyond what you can spend on lightweight trinkets and tools that you can afford to bring to Mars, unless you had some next of kin that you were really dying to leave your inheritance to (pun intended).


"Prior to the late 19th Century, immigrating to America or Australia was pretty much a one way proposition, except for the very richest persons."

Tellingly, in both cases the immigrants were initially criminals and outcasts, and other people only started immigrating once the outcasts had managed (out of necessity) to build something at least vaguely livable to immigrate into.


"And families will be welcome, but only to the degree they produce useful contributors and not idle mouths. No libertarian paradise on Mars or Ceres"

Wait, weren't libertarians capitalists? "If you don't do anything useful you don't get paid, and then you starve." seems pretty accurate.

Anonymous said...

=Milo=



Rick:

"Surely two-way travel will precede one-way travel!"

Well, some people people actually have seriously proposed one-way travel preceding two-way travel, even with groups too small to form a sustainable colony. (Must get awfully lonely.) I don't agree with those proposals, mind.

When I favor one-way ships for initial colonists, it's not because of the lack of availability of two-way options, but because of the much larger requirements compared to other space missions (you need a lot more people, and they need to carry enough tools to build a functioning industrial civilization in a hostile environment, and the vast majority of the mass on the ship is stuff that you need to land on the planet anyway so you might as well just land the ship itself), requirements that are likely to be fairly unique so after your colony ships completes its mission, you aren't likely to need another ship of the same type anytime soon (and this allows you to skimp on launch capability).

Once the colony is properly established, further immigration would be on more ordinary two-way passenger liners. Perhaps most individual passengers only hitch a ride in one direction, but the ship itself gets reused.


"Retirees and kids are non-productive, but still have upkeep costs."

Simple solution: tell astronauts they're not allowed to have kids until they start growing their own food. Now the upkeep costs are the colonists' problem, not yours.


"Putting it another way, a surface base on Mars is a LOT easier than one on Venus, and not even applicable to Jupiter."

If there is a serious interest in a crewed scientific outpost on Venus, then I would expect it to be an orbiting station or survey ship (the latter is able to return to Earth/wherever under its own power when its mission is done). I don't expect Venus to be targetted for large-scale colonization until the development of magitech.

But for colonists, the question isn't whether a surface hab is always better than a space hab. It's just where you can find some planets/moons where a surface hab works better than an orbital one. If so, colonists will aim for those worlds and ignore the others.

In my opinion, good candidates for colonization are: Luna, Mars, most gas giant moons (exceptions are Io for lacking water, Enceladus and Europa for having icy surfaces, Titan for having a human-unfriendly atmosphere and far too much unique charm to be visited as anything except a nature reserve, and perhaps Triton for simply being too far away and there being no good reason to go there - which still leaves 13 moons if I counted right, although you're likely to settle only a few of those at first), and perhaps some dwarf planets if you get strapped for space (again, Kuiper belt objects have desirable compositions but are too far away).

Thucydides said...

The dystopian one way colonization miodel is Australia; which was used as a dumping ground for the criminal elements that English society wold rather not have running around underfoot. Jerry Pournelle extended this trope in the CoDominium stories, which had BuReloc shipping entire ethnic communities, political exiles and other assorted "undesirable" elements (undesirable to the ruling elites of the CoDominium anyway) to distant solar systems.

Of course, trying to do something like this today would both break the bank and be a death sentance to all the transportees, since very few would have the expertise to even plant and operate simple gardens (much less the various technical systems) and members of the criminal class would not have the mental skill sets to patiently work at things so they keep going. If they form roving bands of brigands to steal from the rest, the situation gets even worse in short order. Now some Earthy polities would see this as a feature, not a bug, but fortunatly we don't live in any of these places. It is still cheaper to tkae people out and shoot them anyway.

The situation with the Americas was a bit different. Early colonization was essentially a land grab/gold rush to cash in on easily avalable resources. Later groups of settlers like the Puritains may be considered "outcasts", but still had enough wealth and ability to finance their own expeditions to seek out places where they could practice their beliefs free of persecution. These settlers were content to have self contained settlements with limited economic exchange back to the Old World, which may describe the situation for early colony efforts.

The final waves of colonization were sponsored by elements in the New World seeking cheap labour, creating new markets or to solidify their claim(s) to the territory. The Canadian settlement of the Praries fulfills all three categories, the farmers were sought from Eastern Europe to create the bread basket of the Empire, create an inland market for business in Ontario and Quebec and prevent the Americans from settling and claiming the territories for themselves. Had the British and Dominion authorities had some more time and resources, they would also have liked to flood the Oregon territory with "British" settlers to extend their claim from British Columbia, but for various reasons this project never really got off the ground. (They also missed the boat when the Tsar of Russia put the Alaskan territory on the block; evidently Americans have always been better at land speculation [heh]).

Some elements of the settlement of the New World may describe the situation leading to colonization and settlement in space, the gold rush/land grab trope is pretty common in stories based on the mining of McGuffinite, and should the ability to create self contained colonies become cheap in relative terms I can't see why some groups might not decide to strilke out on their own to practice their religious, social, political or economic beliefs free of interference from their neighbours.

Anonymous said...

Milo: the nearest dwarf planet is Ceres; with the recent finding of water ice in the deep craters on the poles of Mercury, permanent outposts on Ceres may be much more doable then was previously thought. A trip of three or four months to get there, with a (desidedly) little world at the end to live off of now seems like a good prospect for an early exploration destination.


Ferrell

Anonymous said...

=Milo=


Ferrell:

"the nearest dwarf planet is Ceres; with the recent finding of water ice in the deep craters on the poles of Mercury"

Yeah, the problem is that neither of those places have any appreciable advantage over, say, Luna, which is in the same "bland ball of rock but with usefully large supplies of water in the poles" ballpark, with the very significant advantage of proximity. Mercury might be useful if you really love solar power, but I feel solar power doesn't have enough advantages over fission/fusion to be worth settling such a difficult location for (particularly since cooling a hab will be harder than warming one). Settling on Ceres won't make it appreciably easier to access other, smaller, asteroids for mining.

Luna has the advantage of proximity. Mars has the advantage of what looks like a richer world (some atmosphere, even if it's not enough, probably some other stuff), one that actually had liquid water in the distant geologic past, which incidentally also makes it interesting to scientists, and is the next largest place after Earth (already settled) and Venus (unsettlable without magitech), which might interest you depending on what you're after. Most gas giants give you several moons at once for cheap, and most of them also have places of scientific interest (Io, Europa, Enceladus, Titan, maybe Iapetus if you're easily amused...), and larger proportions of (frozen) water than more inward bodies - Jupiter and Saturn will likely be settled for these reasons alone, while Uranus is only interesting if helium-3 is an important MacGuffinite. Saturn's moon Mimas also has both the lightest gravity and the best sky view of any object in the solar system, which is likely to appeal to most of the kind of people who think that colonizing space is cool in the first place.

Ceres? No reason to go there, at least unless we're really strapped for land and have exhausted all other options.

Jim Baerg said...

"Ceres? No reason to go there"

Maybe not Ceres, but determining which asteroids are the sources of the nickel iron meteorites will tell us where to go for siderophile elements, so we have catalysts for our chemical industries & fuel cells.

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

If you've seen my comments on some earlier threads you already know I regard those as one of the less implausible McGuffinites for going into space.

Rick said...

Prior to the late 19th Century, immigrating to America or Australia was pretty much a one way proposition, except for the very richest persons. Immigrating to Mars will be even more expensive

I believe that classic immigration - wherever on the scale of voluntary to forced - has generally been associated with 'cheap land.' Which you won't have in space, short of magitech.

So I would argue for a different model, where permanent settlement is a byproduct of other activities, and 'immigration' is a sub-case of 'travel.'

(So long as deep space travel is Horribly Expensive, you won't have an awful lot of immigrants!)

Anonymous said...

Milo said:"Ceres? No reason to go there, at least unless we're really strapped for land and have exhausted all other options."

I disagree for one importaint reason; research and exploration. (yeah, I know, it sounds like two) Besides the reasons Jim stated, having a 'base camp' in the asteroid belt will help with logistics while exploring them; also, you can practice your techniques for building outposts on the moons of Jupiter and Saturn, but only going about an AU from Earth instead of several.

Ferrell

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