Author Topic: Methalox ISRU on the Moon?  (Read 22294 times)

Offline Pipcard

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Methalox ISRU on the Moon?
« on: 04/07/2016 06:38 am »
The Moon is known to hold deposits of water ice, probably in permanently shaded craters. This is thought to be something that can be processed into hydrolox propellant. ULA plans to use that as part of their CisLunar-1000 vision.

But long-term storage of liquid hydrogen is difficult because of boiloff and hydrogen embrittlement. This has led SpaceX to choose methane over hydrogen for its future launch vehicle(s). Methane is "space storable," and does not require as much specialized equipment for zero boil-off capability. If it were possible to develop methalox ISRU for the Moon, there would also be better synergy with propellant manufacturing systems on Mars.

It has been said that
According to LCROSS, the main component of lunar ice is carbon monoxide, then water, then CO2. Lunar poles ISRU is quite similar to Mars ISRU in that sense.

The lunar cold traps could accumulate other cometary volatiles besides water.

LCROSS ejecta:
N   6.6000%
CO   5.7000%
H2O   5.5000%
Zn   3.1000%
V   2.4000%
Ca   1.6000%
Au   1.6000%
Mn   1.3000%
Hg   1.2000%
Co   1.0000%
H2S   0.9213%
Fe   0.5000%
Mg   0.4000%
NH3   0.3317%
Cl   0.2000%
SO2   0.1755%
C2H4   0.1716%
CO2   0.1194%
C   0.0900%
Sc   0.0900%
Ch3OH   0.0853%
S    0.0600%
B   0.0400%
P   0.0400%
CH4   0.0366%
O   0.0200%
Si   0.0200%
As   0.0200%
Al   0.0090%
OH   0.0017%

As you can see, there's some carbon. Lots of nitrogen too. If the volatiles kicked up by LCROSS came from the same source as the ice sheets detected by mini-SAR radar, there may be abundant carbon compounds there as well as water.

But the issue is that the Sabatier Reaction that is a part of Mars ISRU requires carbon dioxide (which was a much smaller component of the observed ejecta), and carbon monoxide is a waste product (because it was the result of obtaining oxygen from the CO2). I do not know everything about chemistry, so is there any way to turn CO (and hydrogen electrolyzed from water) into methane/LOX propellant?
« Last Edit: 04/07/2016 06:52 am by Pipcard »

Offline Robotbeat

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Re: Methalox ISRU on the Moon?
« Reply #1 on: 04/07/2016 04:11 pm »
Combine it with some of the output oxygen from electrolyzing the water. This still works out because usually you want a fuel-rich mix anyway.
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Offline savuporo

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Re: Methalox ISRU on the Moon?
« Reply #2 on: 04/07/2016 05:30 pm »
Methane is "space storable,"

Can you cite a reference ? Because currently it is not, and as far as i know, not in the foreseeable future. See the reference chart from Handbook of Space technology, ISBN: 9780470697399

Also, there are previous threads on this.
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Offline Robotbeat

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Re: Methalox ISRU on the Moon?
« Reply #3 on: 04/07/2016 07:00 pm »
Methane is "space storable,"

Can you cite a reference ? Because currently it is not, and as far as i know, not in the foreseeable future. See the reference chart from Handbook of Space technology, ISBN: 9780470697399

Also, there are previous threads on this.
It indeed is. You store it in the shade. If your vehicle is a cylinder, have the long axis of the cylinder point toward the Sun. Make sure you use emissivity-optimized paint.

There is no single "temperature" in space. Although you do have to go to extremes to keep hydrogen and helium from boiling off, it's not terribly difficult to keep methane and oxygen from doing so. Note that spacecraft normally get pretty cold in space already, to the extent that hypergolic fuels actually need to be actively heated to prevent them from freezing.
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Offline Doesitfloat

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Re: Methalox ISRU on the Moon?
« Reply #4 on: 04/07/2016 07:01 pm »
https://www.nasa.gov/feature/in-space-manufacture-of-storable-propellants

Above is link to NASA site for" In-Space Manufacture of Storable Propellants"
Updated Feb 2016

Site lists the following as propellants:
Hydrogen
Oxygen
Methane
Methanol
Dimethyl Ether
Hydrogenperoxide

Offline savuporo

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Re: Methalox ISRU on the Moon?
« Reply #5 on: 04/07/2016 07:39 pm »
https://www.nasa.gov/feature/in-space-manufacture-of-storable-propellants

Above is link to NASA site for" In-Space Manufacture of Storable Propellants"
Updated Feb 2016
NASA website also has blog posts about other futuristic stuff, like NIAC interstellar propulsion studies. Just because that blog post from a SBIR company  ( that to date, has not actually flown anything to space ) is published on nasa.gov does not change the current state of the art in space technology.

There is a long way to go before either LOX or Methane can be classified as space storable propellants.
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Offline Robotbeat

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Re: Methalox ISRU on the Moon?
« Reply #6 on: 04/07/2016 08:19 pm »
https://www.nasa.gov/feature/in-space-manufacture-of-storable-propellants

Above is link to NASA site for" In-Space Manufacture of Storable Propellants"
Updated Feb 2016
NASA website also has blog posts about other futuristic stuff, like NIAC interstellar propulsion studies. Just because that blog post from a SBIR company  ( that to date, has not actually flown anything to space ) is published on nasa.gov does not change the current state of the art in space technology.

There is a long way to go before either LOX or Methane can be classified as space storable propellants.
Nope. In your opinion alone.
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Offline Lar

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Re: Methalox ISRU on the Moon?
« Reply #7 on: 04/07/2016 08:48 pm »
Although I tend to give Robotbeat a bit more credence here "you're wrong" ... "no, you're the wrong one", "no you" tends to be quite boring.  Rather than argue about who said what was storable and when, perhaps it would be more instructive to discuss for all our edification what exactly the criteria for storables are.

I had thought that any propellant that could be stored, without suffering boiloff, in LEO or in deep space with only passive temperature control was pretty obviously storable. Is there more to it than that? Is it still storable if it requires active control, but doesn't have to boil off (solar/battery providing energy to drive cooling or heating systems, perhaps)?

THAT said, perhaps the question actually belongs somewhere else... and we should confine discussion in this thread to whether we know enough about lunar ice or other carbon sources to know if methalox ISRU is feasible or not. That's the thread title, not storable propellants...

Some of the prior discussion on lunar methalox seemed to assume that carbon was brought along somehow (just as some early martian methalox assumed hydrogen is brought along) ... is modern thinking still going that way at all?

LCROSS data is interesting but it may be we won't know until we actually send a prospector to take some samples and assay them.
« Last Edit: 04/07/2016 08:52 pm by Lar »
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Offline Oli

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Re: Methalox ISRU on the Moon?
« Reply #8 on: 04/07/2016 10:29 pm »
The methalox stages in NASA's recent Mars plan have cryocoolers. The stages are assembled is cis-lunar space or shipped to Mars orbit with SEP (takes several years).
« Last Edit: 04/07/2016 10:31 pm by Oli »

Offline savuporo

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Re: Methalox ISRU on the Moon?
« Reply #9 on: 04/08/2016 02:25 am »
I do not know everything about chemistry, so is there any way to turn CO (and hydrogen electrolyzed from water) into methane/LOX propellant?

This is done with something called Fischer–Tropsch process, where for terrestrial Gas-to-Liquids plants methane is often an unwanted side product
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Offline Steven Pietrobon

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Re: Methalox ISRU on the Moon?
« Reply #10 on: 04/08/2016 09:07 am »
Reverse steam reforming should do the trick.

CO + 3H2 -> CH4 + H2O, Delta H = –206 kJ/mol

This is an exothermic process. A catalyst might be required. The Hydrogen can be obtained from electrolysing H2O

3H2O -> 3H2 + 1.5O2, Delta H = 711 kJ/mol

Overall reaction is

CO + 2H2O -> CH4 + 1.5O2, Delta H = 505 kJ/mol

That's an oxidiser to fuel ratio of 2.99. Ideally, would like a ratio of 3.5 to 1, which means generating more oxygen. That means 0.255 more O2 will need to be generated.

CO + 2.51H2O -> CH4 + 1.755O2 + 0.51H2
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Offline RocketmanUS

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Re: Methalox ISRU on the Moon?
« Reply #11 on: 04/10/2016 07:01 pm »
{snip}
LCROSS data is interesting but it may be we won't know until we actually send a prospector to take some samples and assay them.
Agree, need to send probes to Lunar surface to confirm if there is carbon source(s) and enough of it.

Morpheus could have been a possible lander for such types of prospector probes.

Offline R7

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Re: Methalox ISRU on the Moon?
« Reply #12 on: 04/13/2016 08:04 am »
NASA website also has blog posts about other futuristic stuff, like NIAC interstellar propulsion studies. Just because that blog post from a SBIR company  ( that to date, has not actually flown anything to space ) is published on nasa.gov does not change the current state of the art in space technology.

There is a long way to go before either LOX or Methane can be classified as space storable propellants.

Methane would freeze behind JWST sun shield. Heck, even oxygen would freeze there.

Equating passive thermal management involving reflective surfaces with NIAC breakthru interstellar ambitions is intellectually lazy.
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Offline savuporo

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Re: Methalox ISRU on the Moon?
« Reply #13 on: 04/13/2016 03:55 pm »
Methane would freeze behind JWST sun shield. Heck, even oxygen would freeze there.

Equating passive thermal management involving reflective surfaces with NIAC breakthru interstellar ambitions is intellectually lazy.
My point is, that propellant isn't a propellant without a functioning propulsion subsystem. You can call a rock propellant, but lacking a functioning mass driver it isn't much of use.
And a liquid biprop propulsion subsystem, especially one that is supposed to fire up after spending months and years in deep space, requires quite a bit more than a tank or a sun shield.
For current space storable propellants, all the required subsystems are catalog items.
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Offline R7

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Re: Methalox ISRU on the Moon?
« Reply #14 on: 04/13/2016 04:55 pm »
My point is, that propellant isn't a propellant without a functioning propulsion subsystem.

It is pointless to argue against lunar methalox ISRU with "current catalogs lack methalox engine therefore no" argument. The methalox ISRU concept happens in the future (if it happens) and obviously assumes that catalogs then do have methalox engines and actual customers using them.

At least two companies are working on methalox engines, and the other plans to use them to get to Mars.
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Offline gospacex

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Re: Methalox ISRU on the Moon?
« Reply #15 on: 04/13/2016 05:42 pm »
https://en.wikipedia.org/wiki/Moon#Physical_characteristics

doesn't look good. Basically, both C and H are rare.

Offline Lar

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Re: Methalox ISRU on the Moon?
« Reply #16 on: 04/13/2016 06:08 pm »
https://en.wikipedia.org/wiki/Moon#Physical_characteristics

doesn't look good. Basically, both C and H are rare.
When viewing the earth as a whole, gold is "rare". And yet people found gold nuggets in streams.

What matters is not what the overall ratios are, but rather whether there are usable concentrations in sufficient quantity to be useful.   700 years from now our ancestors may be cursing that we used up most of the findable CO and H20 on Luna for fuel :) ... but I think LCROSS has shown there is usable water to be found.

From the same WP article
Quote
The 2008 Chandrayaan-1 spacecraft has since confirmed the existence of surface water ice, using the on-board Moon Mineralogy Mapper. The spectrometer observed absorption lines common to hydroxyl, in reflected sunlight, providing evidence of large quantities of water ice, on the lunar surface. The spacecraft showed that concentrations may possibly be as high as 1,000 ppm.[89] In 2009, LCROSS sent a 2,300 kg (5,100 lb) impactor into a permanently shadowed polar crater, and detected at least 100 kg (220 lb) of water in a plume of ejected material.[90][91] Another examination of the LCROSS data showed the amount of detected water to be closer to 155 ± 12 kg (342 ± 26 lb).[92]
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Offline gospacex

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Re: Methalox ISRU on the Moon?
« Reply #17 on: 04/13/2016 06:26 pm »
1000 ppm of water? That's about as much water as in a typical block of concrete.

Offline Nilof

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Re: Methalox ISRU on the Moon?
« Reply #18 on: 04/13/2016 11:31 pm »
1000 ppm of water? That's about as much water as in a typical block of concrete.
That is for regolith, the moon has vast water ice, carbon monoxide, and nitrogen deposits in polar cold traps. Saying that the moon lacks volatiles because regolith is dry is like looking at Egypt and ignoring the fact that the Nile exists. The poles have more than enough volatiles for very large scale colonization.
« Last Edit: 04/15/2016 01:16 am by Nilof »
For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v.   Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

Offline Robotbeat

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Re: Methalox ISRU on the Moon?
« Reply #19 on: 04/14/2016 12:04 am »
My point is, that propellant isn't a propellant without a functioning propulsion subsystem.

It is pointless to argue against lunar methalox ISRU with "current catalogs lack methalox engine therefore no" argument. The methalox ISRU concept happens in the future (if it happens) and obviously assumes that catalogs then do have methalox engines and actual customers using them.

At least two companies are working on methalox engines, and the other plans to use them to get to Mars.
Besides Blue Origin and SpaceX, you also have Masten Space Systems working on a 60klbf methane engine, which they've already test-fired a 45klbf variant. Also, Armadillo Aerospace (now still alive as Exos Aerospace) developed a methane engine used on NASA's VTVL test-bed. Plus Firefly Space Systems, who have also test-fired their upper stage methane rocket engine. Plus XCOR, who test-fired a methane rocket engine a while ago.

So that's 6 separate methane rocket engines in the US alone that have been test-fired recently. In 10 years, every orbital fully liquid rocket in the US may use methane for at least one stage (with the possible exception of RocketLabs and Virgin's LauncherOne if they get built). Pretty absurd to consider methane some exotic propellant.
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