Remember the Bob Zubrin who cast scorn on the idea of propellant depots?
Well, now he has a new proposal:
Zubrin’s concept is, at its core, a space access subsidy program. Rather than spend billions on new launch vehicles, he envisions NASA instead spending a modest amount of money—he suggested $1.2 billion a year, about six percent of its current $18.5-billion annual budget—buying the most “cost-effective” launch vehicles available. That cost effectiveness would be some function of its price and payload capacity; Zubrin has a particular preference for SpaceX’s proposed Falcon Heavy, which could launch up to 53 metric tons into low Earth orbit (LEO) for as little as $80 million a launch.
NASA would then, in turn, resell that launch capacity to itself, other government agencies, and the private sector, at the artificially low price of $50 per kilogram, or about $2.65 million per fully-loaded Falcon Heavy. Those launches, he said, would take place on a regular schedule, regardless if the capacity on each vehicle is fully subscribed. “You don’t hold the train in the station until it fills up,” he explained. Any excess capacity would be filled with consumables like water, oxygen, and propellant, which could be stored on orbit for use by any interested parties.
Emphasis mine.
In what does he propose to store the propellants, if not depots?
I should note, though, to be fair, that he wrote the PJM stuff a few weeks ago, so it’s possible he’s changed his mind.
Used that Jedi mind trick on him, you did.
Used that Jedi mind trick on him, you Elon did.
Oh well. My strike through of “you” was stripped by the html filter.
Anyway, this is a good idea – IMHO – and if at some point the US government sold what consumables were placed on orbit to 3rd parties perhaps the taxpayers could recoup some or all of the launch costs paid to SpaceX.
Not very gracious, Simberg. I like Zubrin’s idea and I’m glad he’s proposing. I’m glad he’s implicitly advocating for propellant depots too.
All of that is way more important than whether you just scored a point in an internet debate.
mrmandais,
Umm… no. Zubrin has a history of taking credit for other people’s ideas and should be called on it.
http://www.youtube.com/watch?v=zNCrMEOqHpc
Doesn’t this cut ‘private’ sales of Falcon? Do I understand SpaceX sells for $80 M and NASA for $2.65 M? Wow! NASA eats $77.35 M which means we tax payers eat it?
Sounds worse than than High Speed Rail. I see no need for NASA to get involved. This is a gross distortion of the private market.
The stages of evolution of a new idea:
“That’s stupid, it’ll never work.”
“OK, the numbers say it could be made to work, but why bother?”
“Let me tell you about this brilliant idea I just had!”
I was told back when I was getting into this business that there is no limit to what you can accomplish if you don’t care who gets the credit. It’s very true.
Ideas are negentropic: the moment someone tells me their great idea, it becomes my great idea. The ability to realize the idea is what translates into the credit that matters: payday.
NASA would then, in turn, resell that launch capacity to itself, other government agencies, and the private sector, at the artificially low price of $50 per kilogram, or about $2.65 million per fully-loaded Falcon Heavy.
Though such a subsidy might look good in the short term, it would put back further improvements in launch systems, we’d be stuck with Falcon heavy like we were stuck with the Shuttle, and you could bet that the costs of producing the Falcon Heavy would steadily rise as a result of the inefficiencies you always get with monopolies.
Doesn’t this cut ‘private’ sales of Falcon? Do I understand SpaceX sells for $80 M and NASA for $2.65 M? Wow! NASA eats $77.35 M which means we tax payers eat it?
I agree that this sounds like a bad idea. It would in effect get rid of one set of monopoly providers (ULA) and replace it with another, while at the same time undercutting any other company from ever being able to establish a market for itself. Ultimately, subsidizies always distort the market and tend to bite taxpayers in the butt.
I was laughing my butt off, I had just read the pj debate the night before and then was reading space review monday morning and I was thinking .. “didn’t zubrin just try and rake Rand over the coals on depots?” So I reread the debate and thought Zubrin should be a politician.
It almost seems his positions are on a ‘felxible path’ regarding which target audience he is addressing.
FWIW, Zubrin was promoting a “transorbital railroad” that would launch “space-storable propellants” back in October.
He was for propellant depots before he was against them.
Like I said, he is on a flexible path!
I am not sure that he actually contradicts himself at all, he is only for depots that enable a flags and footprints mission to Mars, he is against any depot plans that do not – he does not like distractions from his core obsession. He supports any idea as long as it supports his Mars obsession.
Personally I am driven by the desire to scale up humanity into space. And so I have next to no interest in Mars and an intense interest in sustainable economic paths into space (I still do not get why Elon is interested in Mars, he seems reasonably perceptive in other regards). Zubrin seems devoid of any interest in economic sustainability and I personally see him as mostly a completely useless distraction with a perhaps negative influence on space settlement, much like NASA.
Zubrin cares nothing for “how” to get there, only the destination. He fails to recognize the economic disadvantages of gravity wells on top of gravity wells. He disassociates economics from human expansion.
Or what Pete said. (Geez – 2 min late….)
In what does he propose to store the propellants, if not depots?
Spacecraft should fit his (and my) purposes.
This propellant depot idea seems to have gained an importance in peoples minds way beyond any reality, all it does is store propellent, the stuff still has to be brought up to orbit, and then it has to be transferred to some vehicle to do anything useful. It’s like obsessing over the diesel tank out back and forgetting about the tankers that fill it and the trucks that empty it.
No one has forgotten about the tankers that fill it. They are, in fact, a key feature, in that they will compete for business and drive down launch costs.
Spacecraft should fit his (and my) purposes.
If you are proposing that the propellant will be transferred from a launcher directly into a spacecraft, then it is serving at least part of the function of a depot (a place to allow the accumulation of propellant).
Absolutely, and you could call it a makeshift depot. I would reserve the word depot for a system that is dedicated to the function of storing and transferring propellant and such systems would likely use cryogenic propellants, at least for the applications we care about. A refuelable spacecraft would deal with Zubrin’s objections against both unproven technologies and against distractions that might cause his quest for Mars exploration to be delayed, quixotic though his quest may be.
Zubrin has a history of taking credit for other people’s ideas and should be called on it.
I have yet to see any evidence that Zubrin is taking credit for inventing the propellant depot. Put up or shut up.
Though such a subsidy might look good in the short term, it would put back further improvements in launch systems, we’d be stuck with Falcon heavy like we were stuck with the Shuttle, and you could bet that the costs of producing the Falcon Heavy would steadily rise as a result of the inefficiencies you always get with monopolies.
The idea has its problems, but this isn’t one of them. The Transorbital Railroad isn’t an extended cost-plus contract for X launches every year. Its a fixed-price contract put out to bid yearly. You’d select two or three of the least-cost/most reliable providers each year. Zubrin is just using the Falcon Heavy as an example of a likely winner.
New launcher development would be actually be spurred because there would be a substantial customer for cheaper/better launch services.
That said, a much better approach would be to take Zubrin’s yearly $1.2 billion and use it to directly subsidize pounds to LEO (Zubrin’s scheme is an indirect subsidy). The way it works is, at the end of each year the G-11 in charge of all this tallies up the total useful pounds to LEO equivalent put there by US persons, divides it into the $1.2 billion figure, and then writes each payload owner a check depending on the total mass they launched. Advantages are two-fold: first, Zubrin’s system breaks down once mass to orbit exceeds the number of launches he has arranged to buy. There’s a huge knee in the growth curve where all of sudden costs go from $50/kg to $2000/kg, which is crazy. A direct pounds-to-orbit subsidy is much smoother. It automatically self-adjusts to reduce the subsidy per pound as total launch increases. The other advantage is that NASA isn’t having to make high-profile make-or-break decisions about which launcher is the best each year. Instead, the customers would each get to decide on the launch system, which probably would lead to more efficient results in the long run and would allow for more risk-taking.
It’s like obsessing over the diesel tank out back and forgetting about the tankers that fill it and the trucks that empty it.
The whole point (OK most of it) is precisely to provide a market for those tankers at no extra cost to NASA. Consequently the private sector would be able to make a profit on R&D of small RLVs, which would lead them to develop the RLVs, which would lead to cheap lift ($100-$1000/kg), which would lead to both large scale government funded exploration and commercial development of space. The stakes couldn’t be higher.
And ‘forgetting about’ it means leaving it to the private sector, so NASA cannot muck things up. It’s a crucial feature not a bug. I would argue that all R&D and infrastructure development (cryogenic depots, NTR, NEP, tethers etc) could be indirectly financed this way. The way to develop a transport infrastructure is to provide demand for transportation services and to ensure fair, competitive and redundant procurement of those services. The market cannot provide the demand (yet), but NASA could (but stubbornly won’t) and NASA couldn’t deliver an economical transportation infrastructure (yet stubbornly insists it can – at your expense) but the market can. Let each side do what they’re good at and let both sides prosper.
My point wasn’t that fuel depot/s aren’t useful, or essential, but rather that they’re surely only a small part of space exploration, they have no function other than to support other space operations, but people seem to be turning them into an ends in themselves, surely if you’re going to Mars, or back to the Moon to stay you first draw up your mission architecture and propulsion systems and then, way down the list of priorities there’s: fuel depot 350km orbit capacity: X tons H2, Y tons O2.
It all looks a bit like the thinking that gave us the Shuttle, lets build this fantastic launch vehicle, with all these abilities, and then maybe someone’ll think of how it’s to get us to…
The transcontinental raliroads where spurred on by offering favorable loan rates and title to lands along the route. We can’t offer title to anything beyound the occupied orbital slot but NASA could guaranty a market for 200~300 MT of Lox/LH per year at $2500 per kg. That should be enough to support five or six missions per year of a space tug the size of ULA’s ACES 41 and give launch providers an incentive to lower their costs.
I ment to say the $2500 per kg was for delivery to some pre determined orbital depot location, may be ISS adjacent.
My point wasn’t that fuel depot/s aren’t useful, or essential, but rather that they’re surely only a small part of space exploration, they have no function other than to support other space operations, but people seem to be turning them into an ends in themselves, surely if you’re going to Mars, or back to the Moon to stay you first draw up your mission architecture and propulsion systems and then, way down the list of priorities there’s: fuel depot 350km orbit capacity: X tons H2, Y tons O2.
I do think you’re missing the point. Under the Apollo approach, you launch everything you need for the mission on one gigantic and gigantically expensive rocket. For each KG of payload you actually deliver to LEO (much less to the moon or Mars), you need about 15-20 KG of rocket and propellant at the launch pad. From LEO, you need a lot of propellant to mount a deep space mission. Eliminating the need to launch all of that propellant at once, you eliminate the need for the gigantic and gigantically expensive rocket. Propellant depots can radically lower the cost of deep space missions. This drives the architecture for the mission.
Depots also make possible space tugs which could radically reduce the cost of putting payloads into GEO. From memory of an old article, a Proton booster can put 20 metric tons into LEO (say a space station module) or 2 metric tons to GEO. Those other 18 metric tons are taken up by an upper stage and its propellant. The Proton is severely disadvantaged by the latitude of its launch site but those are the numbers I remember. Now, the customer for the launch only cares about getting his 2 ton payload to GEO. Suppose he could launch it to LEO on a smaller, less expensive booster. Once there, a space tug could rendezvous and dock with the satellite and take it to GEO. Once it releases the satellite, it does a big burn to lower the perigee and uses aerobraking to lower the apogee until it returns to its parking orbit to await the next launch. The tug is refueled from the depot and is fully reusable. The launch customer doesn’t have to buy a bigger rocket than what is needed to lift the payload to LEO, and the biggest factor driving the cost of the tug services is the cost of getting the propellant to LEO. Since you’re routinely delivering propellant on ordinary boosters, you’re increasing your launch rate which is one of the biggest factors in reducing costs to orbit.
Larry, GEO transfers for satellites using a chemical rocket propelled reusable space tug is not a very convincing argument.
Rockets can get about half their LEO into a geosynchronous transfer orbit, then the satellites use on board propulsion to circularize their orbits into GEO. The problem with using space tugs in the way you’ve described is that after you’ve boosted the extra mass of the space tug itself to GEO, and then returned it to LEO, you’ve actually used more mass than you would using the present method. You mention aerobraking but that saves little mass when the heat-shield (admittedly it could be fairly light compared to re-entry shields) has to do the round trip as well, and of course the aerobraking maneuver is another complication. Then you have to service the tug, even my car needs servicing every two or three years.
It seems the more practical route to save propellant getting satellites to higher orbits is to use solar electric systems, more time, less mass.
MPM @ 2:45 The market cannot provide the demand (yet), but NASA could (but stubbornly won’t) and NASA couldn’t deliver an economical transportation infrastructure (yet stubbornly insists it can – at your expense) but the market can. Let each side do what they’re good at and let both sides prosper.
Well said!
And so I have next to no interest in Mars and an intense interest in sustainable economic paths into space (I still do not get why Elon is interested in Mars,
Because Elon served on the Mars Society’s steering committee. That’s why he started SpaceX in the first place. Everything else is a means to the end. (Fortunately, he has chosen more rational means than Zubrin has.)
The real question is: how do you later transition from artificial low cost space access to real low cost space access. If your answer is “you don’t” then you’re missing the point. The purpose of a launch subsidy like this would be to create the market demand for which low cost space access would service. So do you just cut everyone off after 10 years? Do you have a law which says the government price will never be lower than any market price?
When you answer that question I’ll comment on whether or not I think its a good idea.. after some due consideration.. but right now the idea is half-baked.
Trent,
I had an idea similar but structurally different to Zubrin’s once. NASA buys a bulk amount of modular medium lift launches, and then resells each launch for individual cost in the bulk buy. Then the market can access launch costs at high system flight rates without there being actual consolidated demand yet. NASA only pays the difference between actual usage, and arbitrary procurement rate, and can use the difference for its own purposes, notionally storing hypergolic propellant at strategic space nodes for future exploration use when it builds up over time, like how a dripping faucet can fill a bathtub.
The subsidy ends when actual demand meets arbitrary procurement rate, or NASA terminates the experiment when it doesn’t or the program doesn’t work for them anymore. NASA would get a reasonably good deal for its exploration missions, while boosting domestic flight rates and lowering costs for other users of space launch.
NASA would not be setting and subsidizing an arbitrary low launch cost that may not be sustainable without subsidy, but rather, subsidizing a high flight rate system whose costs would be real at that arbitrary flight rate. When actual demand meets that flight rate, then the system is able to accommodate it without NASA support.
Example:
NASA buys 52 flights a year of Falcon 9(with F9H being able to service existent market beyond F9 capacity)*
Let’s say F9** sells for 55 million now, but if NASA bought 52 of them a year, it would cost less by some amount. Let’s say 40 million apiece. NASA would sell each flight for 40 million, and eat the launches unsold.
NASA/Broker resells flights: Some for COTS, Some for GEO Market, some for DoD missions, Some for NASA Science, Some for prospective new industries hopefully enabled by lower launch costs. Even the existing markets collectively have substantial demand.
NASA uses excess flights for exploration purposes. A hypergolic space economy ideally, similar/identical to what Martijn Meijering talks about. Hypergolic propellant has the advantage of being able to be stored for many years in space, and thus serves as a good filler payload when there aren’t enough real payloads.
NASA only pays for the launches beyond actual usage, and from that gets a good deal for its incidental exploration usage. As actual usage appears or increases, NASA can either phase out arbitrary rate procurement or keep it to backstop system health or keep expanding the arbitrary rate.
*Actually, I’d start things off by competing a billion or two between prospective launch providers for establishing their high flight rate modular medium lift contender.
**What NASA would procure would not be launch vehicle per se, but a payload envelope to given parameters, which then could become a standard. Payloads could build to this standard.
I call the idea, Consolidated Multi Launch Corp., or The Hypergolic Space Economy.
NOFBX is a possible candidate to fuel a Hypergolic Space Economy.
“The statements against propellant depots are no longer operative.”
libs0n,
that’s a good architecture. I like my alternative better, because it allows the commercial market to explore the reusables, small launch, and heavy launch space. But yours isl pretty sensible and sellable. It sounds more politically doable than Zubrin’s plan or my alternative.
Trent Waddington,
see my alternative transorbital railroad architecture above. The subsidy (on a per kilogram basis) inherently decreases as flight rates increases. When you’re reaching the point where you’d want to cut off subsidies (probably the magic number of $100/kg or thereabouts), the subsidies are no longer that significant anyway. But I’d favor baking the $100/kg cut-off into the cake to start with.
I can forgive Mr. Zubrin (years ago at the Smithsonian A&S museum bookstore I covered up “The Case for Mars” with “The High Frontier”). I think the idea is for us to move in some, if any direction. In the 90’s that direction still involved the Space Shuttle/ISS etc.
Mr. Zubrin is still talking about NASA, however. If the government is going to do ‘not’-depots, why not stand up that US Space Guard (Orbital Guard)? Can NASA really administrate something like this even at all? Should it? Well, no, it shouldn’t.
The Hypergolic Space Economy.
Nice phrase! I’d avoid emphasising the word hypergolic though, since it draws attention to a somewhat desirable but not at all crucial feature. The crucial properties are being capable of being transferred and stored in space with existing technology. Storable or non-cryogenic may be a better word, although even deep cryogenics will eventually be storable too. As Bill White rightly points out NOFBX could be a candidate, as well as HAN, DMAZ, hydrogen peroxide, and various alcohols and hydrocarbons.
(Deep) Space Propellant Economy perhaps?
Starting with refuelable storable spacecraft in high energy orbits (primarily L1/L2, perhaps MEO / GEO) would be a significantly smaller challenge than first generation cryogenic depots in LEO, yet not much less capable.
Sounds like carbon trading, but using propellant instead of carbon.
“That said, a much better approach would be to take Zubrin’s yearly $1.2 billion and use it to directly subsidize pounds to LEO (Zubrin’s scheme is an indirect subsidy).”
Better yet.
Suppose NASA wants to explore the moon. It starts buying rocket fuel delivered to the Moon. It spends 200 million per year until the time it launches crew to the moon.
The result will be that NASA’s Manned lunar exploration will cost about 1/2 of what it would cost without having rocket fuel on the Moon.
So NASA spends a couple billion and saves couple tens of billion.
If NASA does use all the rocket fuel, it sell it to anyone- at same cost it spent for it, or maybe at 1/2 the price.
The first rocket fuel shipment will pay twice as much per lb of rocket fuel, and it will test storing hydrogen in the dark craters of the Moon.
The next hydrogen shipment isn’t paid this twice rate, but first LOX’s first shipment would get twice the price. As would other selected fuels, such kerosene.
The first shipment must provide evidence that, that fuel can be safely stored on the lunar surface.
So, the base rate for shipping rocket fuel to lunar surface should be say $20,000 per lb, or 40 million per ton. So per year NASA gets 2/12 tons. And in 10 years gets 25 tons- enough rocket fuel for about 4 crew returns or if have 2-4 crew per trip, then 8 to 16 total crew returned.
Each year it could take a bid, if no one offers to deliver or fails to deliver the rocket fuel, then money should transferred to the next year.
I guess if you want 5 tons a year, and perhaps want rocket fuel delivered to Mars you could instead spend around 400 million per year.
Launching the propellant to LEO or L1/L2 instead of the lunar surface is much less of a challenge and will therefore likely lead to reductions in launch prices more quickly. Of the two L1/L2 is more useful for applications, while LEO is more convenient for launchers. In addition L1/L2 could help stimulate development of the in-space part of a transportation infrastructure.
(partial repost coming up)
For the past thirty years NASA has been spending ~$3.5B/yr on launches. Unfortunately, that money was all spent on a single launch vehicle, the Shuttle. I would like them to continue to spend that much money on launches, but this time competitively.
But $3.5B/yr worth of launch services requires a large tonnage of payloads, even at today’s launch prices. That tonnage cannot consist of spacecraft, since that would be far too expensive. Commodities like propellant for exploration or water for radiation shielding are ideal, since they are both cheap and needed in large quantities for exploration.
If this is to happen quickly enough to satisfy the porkmeisters, then it will have to be done with storable propellant or water. This might lift everybody’s boat and help open up space for mankind in the process.
You would still need a spacecraft or transfer stage to consume the propellant or to contain the water. Fortunately a large pork spacecraft is being built as we speak, namely Orion/MCPV. If we were to take its service module and avionics and give it bigger fuel tanks we could build a hypergolic transfer stage out of it. It could be a 21st century beyond-LEO Agena.
A later incarnation could serve as a propulsion module for a Nautilus spacecraft and remain useful for high Mars orbit insertion, trans-Earth injection and insertion into high Earth orbit, probably L1/L2 even until long after we had cryogenic depots.
Removing NASA from the crew launch and return business would have another desirable side-effect, it would remove a dangerous threat to commercial crew. The crew module part of Orion could still be turned into a commercial crew taxi (with no special privileges over the others), thus potentially building on past investments and satisfying some of our friends in Congress. This would only happen if LM so decided and if it won a contract. There would be nothing wrong with such an Orion Light or Agile Orion and it could be used for commercial purposes too.
The hypergolic Orion-derived transfer stage doesn’t completely solve the spacecraft problem, since you probably want to move an unmanned science payload on it. Where would we get the money for such a spacecraft? I think NASA’s SMD could be the answer.
Until NASA HSF itself has an immediate purpose for the propellant launched using its budget, it could sell the propellant to the highest bidder, perhaps both in LEO and at L1/L2, but probably only the latter. If Discovery and New Frontiers class missions were to be provided with hypergolic transfer stages as government furnished equipment this would facilitate their role as a propellant buyer. This would establish competition both on the launch services side and on the science mission side and maximise the additional science return on top of the strategic value of investing in cheap lift.
This should have a major impact on the cost of science missions. In addition to getting a free transfer stage from L1/L2 and very cheap, highly subsidised propellant at L1/L2, even the launch costs for the spacecraft itself would drop significantly as EELV launch prices would automatically come down because fixed costs would now be divided over more launches.
In addition the projects could focus their time, money and energy on their science missions instead of innovation in propulsion / aerobraking etc by using brute force solutions with cheap subsidised propellant. The innovative role could be left to the market which would want similar (but not identical) innovations for RLVs and would be able to afford them.
In order to generate enough missions soon (hypergolics don’t boil off but politicians might like to see results they can sell to the public), NEOs and main belt asteroids may provide interesting targets. There are many of them, they are of intrinsic scientific interest and in the long run they could be interesting for their resources.
Maybe you could get economies of scale on the spacecraft side too, either by longer production runs or even propulsive return of the spacecraft (say for sample return to L1/L2) or by having a common ground segment.
“Launching the propellant to LEO or L1/L2 instead of the lunar surface is much less of a challenge and will therefore likely lead to reductions in launch prices more quickly. Of the two L1/L2 is more useful for applications, while LEO is more convenient for launchers. In addition L1/L2 could help stimulate development of the in-space part of a transportation infrastructure.”
Yeah launching to LEO or L-1 could better in terms of lowering launch costs. But having rocket fuel at the Moon would make a NASA lunar manned mission cheaper, so it’s better for NASA.
If you doing a manned mission to Mars or the Moon having rocket fuel at their surfaces will significantly lower the program costs.
In other words if you gave the rocket fuel for free to NASA in LEO or L-1 and compared that to NASA paying $20,000 for rocket fuel at lunar surface, buying the rocket fuel would be a bigger reduction in the program cost.
Having rocket fuel on the surface is a value to NASA and a value to anyone thinking of doing any kind of operation on the Moon.
A comparable value would be the ability to use a fully fueled lunar lander.
If anyone puts rocket fuel in L-1, then someone should be to start a business of using a reusable lunar lander/return- and so have the same thing.
But for NASA until someone is providing a lunar lander, simply having rocket fuel at the lunar surface is the cheapest option.
In addition having rocket fuel at the lunar surface could have other purposes other than just being used by a ascent vehicle.
So if NASA wants to go to the Moon [and they want to get there is the shortest time into the future]. The cheapest, quickest and most certain way of doing a manned lunar programs- is buying rocket fuel on the Moon.
Same applies with Mars.
You’re actually making a strawman, albeit I don’t think deliberately.
Hydrogen is utterly stupid to try to store for extended periods, especially in space. Methane and Oxygen have much better “shelf life”, but not as good an ISP. RP1 is room temperature, and used by the Falcon series. So if you want to depot oxygen and RP1 – that doesn’t invalidate Zubrin’s just criticism of hydrogen storage.
It still leaves my issue with a propane tank on a shooting range with so much space junk, but that’s my beef, not his.
“You’re actually making a strawman, albeit I don’t think deliberately.
Hydrogen is utterly stupid to try to store for extended periods, especially in space. Methane and Oxygen have much better “shelf life”, but not as good an ISP. RP1 is room temperature, and used by the Falcon series. So if you want to depot oxygen and RP1 – that doesn’t invalidate Zubrin’s just criticism of hydrogen storage.
It still leaves my issue with a propane tank on a shooting range with so much space junk, but that’s my beef, not his.”
The dark craters of the Moon temperature is at Hydrogen’s critical point temperature to be liquid:
Hydrogen 33.24 K 12.797 atm [about 188 psi]
http://www.engineeringtoolbox.com/critical-point-d_997.html
So 33.24 K equals -239.91 C
“The craters’ towering rims block the sun from reaching their centres, like the long shadows cast by tall buildings at dusk. In this permanent darkness, they stay at a constant -240 °Celsius – more than 30 °C above absolute zero and 10 °C cooler than Pluto’s dayside, which was measured at -230 °C in 2006.”
http://www.newscientist.com/article/dn17810-moon-is-coldest-known-place-in-the-solar-system.html
So it could be possible to store Hydrogen in the Moon’s dark craters.
And should able to take hydrogen gas at around say 300 psi, and liquify it by allowing it to cool on lunar craters. Or inject liquid hydrogen into say 100 psi gas, in tank that can withstand high pressure, and let it cool in craters.
Therefore it might possible to store liquid hydrogen in dark crater on the Moon for decades, without boil off and without refrigeration.
How much gear/energy would it take to store hydrogen as a pressurized gas instead, and only liquify it on demand? Yes, I know it’s both complex and a fair chunk of energy – but it should be necessarily less than mining it from ice, hydrolyzing it and -then- liquifying it.
“Or inject liquid hydrogen into say 100 psi gas, in tank that can withstand high pressure”
My bad- that wouldn’t work.
You need to pressurize it.
Heh, that’ll teach me to not refresh first 😀
Still curious how much heat dumping capacity a simple one cubic meter lunar pit would end up actually managing at, say, 100K (as opposed to my first-order calcs).
I just read his transcontinental railroad model for space expansion.
http://www.washingtontimes.com/news/2011/may/24/treating-space-like-the-american-west/
One problem with this metaphor: the Western end of the railroad was as easily settled as the eastern end. I learned from Sid Meier’s Railroad Tycoon that a railroad isn’t worth it unless:
a) There has to be commercial activity at both Points A and B;
b) Point B has raw materials that Point A can exploit profitably via rail line.
Question for history buffs: didn’t the British have a major rail boondoggle in India where rail was built well in excess of the demand for such transport?
Still curious how much heat dumping capacity a simple one cubic meter lunar pit would end up actually managing at, say, 100K (as opposed to my first-order calcs).
In addition in terms of mass when you split water you get a mass of hydrogen per 8 masses of Oxygen [hydrogen is 16th the mass but there 2 hydrogen for each Oxygen- H2O]
Specific heat hydrogen 175K 13.12 kJ/kg.K
Water at −10 °C (ice)[20] solid 2.11
Without trying to figure it out, I would say need around a ton or 2 of frozen dirt to chill a ton of hydrogen. Or 1 ton of water [ice] chills ton of hydrogen.
Or If water is 10% of mass of dirt- the dirt you dig up to mine the water will chill the hydrogen. Or by pressurizing the hydrogen you should have enough heat to warm dirt so can remove the water- though you will need addition energy.
Not sure, what asking but if you are mining water, you will have no shortage of cold.
The coldness of dark craters isn’t a problem for a person to walk around in- other than you might have cold feet [and that’s unlikely] a person in spacesuit in dark crater will need a cooling system- just as you do in sunlit areas on the moon.
Machines digging stuff and hauling stuff is different matter. Machines aren’t evenly warmed like a human body [nor are they in pressurize spacesuits] a machine’s engine in a dark crater could be hotter than engine running on earth, but all kinds of other things which aren’t generating heat could get extremely cold.
But things which aren’t in contact with cold material, will take a long time to cool