Author Topic: Free Launch, or Mars Clathrate Mining  (Read 1448 times)

Offline LMT

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Free Launch, or Mars Clathrate Mining
« on: 12/22/2017 06:09 AM »
The Idea

From “Methane Hydrate on Mars: A Resource-Rich Stepping Stone to the Outer Planets?

Quote
The detection of methane establishes the subsurface of Mars as a hydrocarbon province...  Methane gas and hydrate deposits may occur in the subsurface at shallow depths on the order of ~15-30 m.  Shallow methane gas deposits could constitute the most important near-term in-situ resource.  Utilizing the natural resources of Mars could significantly reduce the cost of human exploration when compared with what would be required if these same resources were transported from Earth.  In fact, the availability of these natural resources may prove to be the critical factor that will enable the continued human exploration of the solar system.

A new paradigm of a resource-rich Mars should now be considered the basis of the planning of future human exploration, whether on Mars or beyond -- turning Mars from a remote, dead-end destination to a self-sustaining outpost that can serve as a stepping stone to the outer Solar System.

It's just an idea.  An "advanced concept," we can say.

Theoretically methane from underground can be trapped in martian ice as clathrate, especially atop fault lines, which may channel methane toward the surface.  Thereby ice-rich regions such as ice caps could conceivably accumulate clathrate.  A regional clathrate deposit could contain enough methane to justify mining for spacecraft use.

SpaceX estimates propellant production could use more than half of a facility’s electrical power.  Hypothetically a clathrate mine would free that power for use elsewhere.  If methane manufacture is not required, oxygen production can use less power also.  One might replace power-hungry water electrolysis with oxygen-byproduct harvesting in, say, dense algae oxygen farms, or in some existing oxide-reduction factory.  Result:  a very significant reduction in facility power requirement.

What would be some basic challenges of such a venture?  They include:

- Prospecting:  locate a rich clathrate deposit
- Mining:  get methane out of the ice
- Storage:   store methane at fleet scale

All would have to be done efficiently of course. 

Clathrate Prospecting

Clathrate prospecting on Mars is certainly speculative.  But perhaps some terrestrial prospecting tech could be adapted for this purpose.  Might reflection seismology be applicable?  Clathrate prospecting on Earth has been performed using seismic methods.  Examples: 1, 2

If a seismic method were workable on martian ice caps, a spacecraft might implement.  For example it could deploy small self-guided impactors across the cap, to produce a gridded set of seismic impacts.  The spacecraft would also deploy small sensors across the ice cap, perhaps as lightweight autorotation landers, to record the dataset of impact seismic waves.  Prospecting software would convert the dataset into a model of the ice cap, marking possible clathrate deposits.

What other prospecting methods might be feasible? 

Clathrate Mining and Methane Storage

How might clathrate mining and methane storage be accomplished, efficiently and at fleet scale?  Conceivably, and rather simply, one might use heat as a mining tool, and use the ice cap as a storage vessel.  Illustrating one such scenario, just as an “ice-breaker”:



Here an ice cap is dark blue, with a landed spacecraft at top right.  Clathrate is mined with a Kilopower-class reactor (red).  The reactor produces electrical power and heat for mining.  Reactor melt hollows out chambers. 

The reactor would be cooled by vapor convection inside the chamber.  Radiated heat vaporizes ice, and convecting vapor circulates, removing heat from the chamber when released.

In deployment, the reactor is lowered quickly from the surface, forming a narrow ice pipe.  At clathrate depth the speed is reduced, to allow the reactor to melt out the greatest possible chamber diameter and maximize methane release.

In this merely conceivable scenario, multiple chambers are melted out and used for several purposes.  Purposes are noted in the following production and storage steps:

1.  An active clathrate methane mining chamber has a cap which opens to release the warm vapor into insulated surface piping.

2.  The pipe connects to an evacuated vessel chamber, mined out previously, now serving as a vapor separator.  In this cold chamber the high-fraction water vapor freezes out (light blue), leaving methane, nitrogen, CO2 and other clathrate components in vapor phase or gaseous phase.

3.  The vapor separator’s cap opens and the remaining gases are pumped into surface piping.  Notionally the cap employs low-pressure membrane filters to separate nitrogen, CO2 and other unwanted impurities out of the gas stream, venting them into the ambient atmosphere.  This leaves methane product in the pipe.  The separator chamber is now evacuated for reuse.

4.  The pumped methane is compressed into the liquid methane storage chamber vessel.  The methane is compressed above 10 atm pressure to hold it in liquid phase at ambient ice cap temperature.  No refrigeration is required.  This chamber vessel would need to be created at a depth having ice strength adequate for the pressure vessel.  (Open question:  How quickly would methane escape into the surrounding ice?)

5.  The liquid methane vessel’s cap opens to pump liquid methane into the awaiting spacecraft.  The spacecraft’s methane tank is filled completely, but only a fraction is used in the hop to a Mars facility.  The balance is used for the return flight, and to fuel another craft at a Mars facility.  That excess methane is essentially “in-tank cargo”.

LOX Storage

Assuming as before that oxygen is now a facility byproduct, LOX bulk storage remains a problem.  The infrastructure to store LOX for a fleet of spacecraft could require immense ISRU manufacturing at a Mars facility (assuming Omaha Crater reservoir inflatables are not available).  To get around that problem, spacecraft might tank extra LOX in the ice cap alongside methane.  This LOX would be carried essentially as in-tank cargo, on the hop from a Mars facility to the clathrate mine.  After the spacecraft lands, its excess LOX is pumped into a storage chamber vessel that’s similar to the liquid methane vessel. 

One difference:  LOX would need refrigeration.  Refrigeration requires power, but less in an ice cap than at a Mars facility.  And of course the power saving derived from the hypothetical clathrate mine would be immense.  Altogether this might not be a completely “free launch,” but if feasible it would be at least a “cheap launch.”   

Open topic.

Refs

Gas-hydrate concentration estimated from P- and S-wave velocities at the Mallik 2L-38 research well, Mackenzie Delta, Canada
Geophysical methods to quantify gas hydrates and free gas in the shallow subsurface: Review and Outlook
Methane Clathrates in the Solar System
Methane Hydrate on Mars: A Resource-Rich Stepping Stone to the Outer Planets?
Methane Seepage on Mars - Where to Look and Why
Nuclear Systems Kilopower Overview
« Last Edit: 12/27/2017 04:39 PM by LMT »

Offline john smith 19

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Re: Free Launch, or Mars Clathrate Mining
« Reply #1 on: 12/26/2017 06:46 AM »
The Idea

From “Methane Hydrate on Mars: A Resource-Rich Stepping Stone to the Outer Planets?
Depending on the volumes involved this could be huge.

Many mfg processes (metal smelting, glass and concrete production) are very energy intensive. a large supply of indigenous hydrocarbon fuel radically simplifies the ability of any settlement to expand.

A key question would be wheather this is a continuous process or if its a finite reserve, but just the availability makes a very big change to what it takes to make ISRU viable.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.
So you're going to Mars to seek a better life. What does that mean to you? Always spot a fanbois by how they react to their idols failures.

Offline LMT

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Re: Free Launch, or Mars Clathrate Mining
« Reply #2 on: 12/27/2017 12:38 AM »
The Idea

From “Methane Hydrate on Mars: A Resource-Rich Stepping Stone to the Outer Planets?
Depending on the volumes involved this could be huge.

Many mfg processes (metal smelting, glass and concrete production) are very energy intensive. a large supply of indigenous hydrocarbon fuel radically simplifies the ability of any settlement to expand.

A key question would be wheather this is a continuous process or if its a finite reserve, but just the availability makes a very big change to what it takes to make ISRU viable.

Potentially huge, yes.  Worth the prospecting effort, don't you think?

Scale

The generative process could be dormant today; accumulation over geological time is the thing.  Pure clathrate is ~13 wt% methane, so even a small deposit would be useful.  1 km3 of pure clathrate releases ~120 billion kg of methane, enough for ~500,000 fully-loaded ITS Mars launches.

Faster Prospecting

Say we take seismic surveying as the baseline prospecting method.  What methods could deliver faster results?  Perhaps a remote sensing method could be applied.  For example, radar can penetrate polar caps from orbit, revealing much internal detail:



But can radar detect clathrate under ice?  At least one such method has been suggested, but I haven't seen application.  See "A combination of radar and thermal approaches to search for methane clathrate in the Martian subsurface".

Oxygen

Discovery of a clathrate deposit would bring the question of oxygen production to the forefront.  Every kg of methane reacts with 3.6 kg of oxygen, so efficient bulk O2 production would be needed.  At Omaha Crater a subaqueous dome could be dedicated for that purpose:  2 million+ sunlit m3 would support a practical, industrial-scale algae O2 farm, suitable even at present efficiency.  If such a large space weren't available, farm O2 output at that scale would call for improved conversion efficiency, volumetrically at least 2 orders of magnitude above present algae-farm efficiency.  One potential improvement under study:  "Magnetic treatment of microalgae for enhanced product formation".
« Last Edit: 12/27/2017 04:04 AM by LMT »

Offline john smith 19

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Re: Free Launch, or Mars Clathrate Mining
« Reply #3 on: 12/27/2017 08:02 AM »
Potentially huge, yes.  Worth the prospecting effort, don't you think?
If the numbers check out definitely. Setting up a Mars settlement is going to be very risky. Anything that loads the dice in favor of success in the first landing is a good idea, as decisions like that have consequences (good and bad) that can be very difficult to correct later.

Quote from: LMT link
Scale

The generative process could be dormant today; accumulation over geological time is the thing.  Pure clathrate is ~13 wt% methane, so even a small deposit would be useful.  1 km3 of pure clathrate releases ~120 billion kg of methane, enough for ~500,000 fully-loaded ITS Mars launches.
That certainly puts the scale in perspective. Clearly enough there for both fueling return flights and building out the settlement.

Quote from: LMT link

Faster Prospecting

Say we take seismic surveying as the baseline prospecting method.  What methods could deliver faster results?  Perhaps a remote sensing method could be applied.  For example, radar can penetrate polar caps from orbit, revealing much internal detail:



But can radar detect clathrate under ice?  At least one such method has been suggested, but I haven't seen application.  See "A combination of radar and thermal approaches to search for methane clathrate in the Martian subsurface".
As noted on the BFS 2.0 thread MRO has a ground penetrating radar supplied by the Italian space agency ASI. While it's unclear if it'll detect surface dust (which was the context of the discussion) it's specifically designed to detect subsurface layers, certainly on a good enough resolution to find these sorts of features. I think it's good for up to 4Km below the surface.
Quote from: LMT link
Oxygen

Discovery of a clathrate deposit would bring the question of oxygen production to the forefront.  Every kg of methane reacts with 3.6 kg of oxygen, so efficient bulk O2 production would be needed.  At Omaha Crater a subaqueous dome could be dedicated for that purpose:  2 million+ sunlit m3 would support a practical, industrial-scale algae O2 farm, suitable even at present efficiency.  If such a large space weren't available, farm O2 output at that scale would call for improved conversion efficiency, volumetrically at least 2 orders of magnitude above present algae-farm efficiency.  One potential improvement under study:  "Magnetic treatment of microalgae for enhanced product formation".
IIRC SX are talking about using the sort of systems developed for the ISS for O2 production, using CO2 and water to get Methane and O2. With a ready supply of Methane I guess you could skip most of the process and go with water electrolysis, logically starting from the ice that held the Methane to begin with.

The "perfect" landing site is therefor one that combines good deposits of water, methane, strong sunlight and is on the Equator (to gain free velocity from equatorial spin).

Probably impossible IRL but those would seem have the absolute best possible shot at a viable settlement.

On improving Algae efficiency I'd note it depends how you measure efficiency to begin with. My instinct is to identify processing stages and look for small(ish) improvements in each of them that multiply up.

For algae an obvious option would be to take samples of as many algae species as possible, then place them all in an environment which selects for higher O2 production, essentially forcing them to evolve. Of course this would have to be baselined around the conditions on Mars you're expecting them to work in. Once you've found a winner identify the improved versions of the key genes then place them in an algae which is genetically stable, so it breeds true.

 
« Last Edit: 12/27/2017 12:01 PM by Lar »
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.
So you're going to Mars to seek a better life. What does that mean to you? Always spot a fanbois by how they react to their idols failures.

Offline Lar

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Re: Free Launch, or Mars Clathrate Mining
« Reply #4 on: 12/27/2017 12:03 PM »
Before getting too excited about this, I think there needs to be a good chance that these exist at scale. Prospecting is part of it (required) but another part is an explanation of how this methane was sequestered. Where did it come from in the first place? What was the geological process that sequestered it? If no explanation can be devised, the likelyhood goes down, in my view.

Producing O2 with algae kind of begs the question of what to do with all the algae produced? It seems imbalanced... Might be better to break down CO2 and dump the solid carbon.

This search might find more articles that substantiate the venting, if not the clathrates.

https://www.google.com/search?q=mars+methane+vent+plume&ie=utf-8&oe=utf-8
« Last Edit: 12/27/2017 12:29 PM by Lar »
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline LMT

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Re: Free Launch, or Mars Clathrate Mining
« Reply #5 on: 12/27/2017 03:19 PM »
Where did it come from in the first place? What was the geological process that sequestered it? If no explanation can be devised, the likelyhood goes down, in my view.

"If no explanation can be devised" ? 

See for example one of the given refs, Methane Seepage on Mars - Where to Look and Why.  It's a good starting point.


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Re: Free Launch, or Mars Clathrate Mining
« Reply #6 on: 12/27/2017 06:16 PM »
Before getting too excited about this, I think there needs to be a good chance that these exist at scale. Prospecting is part of it (required) but another part is an explanation of how this methane was sequestered. Where did it come from in the first place? What was the geological process that sequestered it? If no explanation can be devised, the likelyhood goes down, in my view.

Producing O2 with algae kind of begs the question of what to do with all the algae produced? It seems imbalanced... Might be better to break down CO2 and dump the solid carbon.

This search might find more articles that substantiate the venting, if not the clathrates.

https://www.google.com/search?q=mars+methane+vent+plume&ie=utf-8&oe=utf-8

Well growing algae is breaking down co2. You can easily remove the carbon part and dump it but remember algae is edible and can be used for other things from feeding fish to increassing the organic carbon content of soil.

Offline Bob Shaw

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Re: Free Launch, or Mars Clathrate Mining
« Reply #7 on: 12/27/2017 06:58 PM »
Clathrates on Mars would be good, but there's too much-handwaving so far regarding recoverable deposits. We can't count on finding any (yet) but we *can* count on finding H20 and CO2 - these must the feedstocks upon which early Mars settlement will depend. H20 ice can be found, freshly exposed, at recent impact sites across the planet - and they are regularly, if unpredictably, replenished. CO2 is literally floating everywhere in the air (it *is* the air, mostly!), or available to be shovelled off the ground during high latitude winters

Obviously, serious geological exploration and attempts to find clathrates can then come along - but not until the H20/CO2 economy is up and running.

The elephant in the room for all this, from early ISRU to deep clathrate exploitation, will be serious supplies of electricity and heat.
« Last Edit: 12/27/2017 07:00 PM by Bob Shaw »

Offline LMT

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Re: Free Launch, or Mars Clathrate Mining
« Reply #8 on: 12/27/2017 07:04 PM »
IIRC SX are talking about using the sort of systems developed for the ISS for O2 production, using CO2 and water to get Methane and O2. With a ready supply of Methane I guess you could skip most of the process and go with water electrolysis, logically starting from the ice that held the Methane to begin with.

Reactor vaporization would give you water vapor for electrolysis, yes.  However electrolysis itself is an energy hog, taking ~16 million Joules for every liter of water dissociated.  If clathrate were available, one would gladly forego hydrogen production entirely, dropping electrolysis to focus on some low-energy oxygen production method. 

And pond scum is really low-energy.  :) 

Of course other plants have their own tricks, and some plants are tasty.  Notably, wheat loves high-intensity light.  2 acres of wheat, lit with spectrum-optimized LEDs and kept in continual hydroponic use, could produce ~ a billion calories over a Mars year:  loaves for the multitude, and the oxygen byproduct should be considerable. 

Wheat's requirements for energy, space, nutrients etc. would have to be weighed against those of algae and other potential O2-producers, in the selection process.  Personally I think a crop's potential contribution toward pizza production should be a heavily-weighted factor.

« Last Edit: 12/27/2017 11:47 PM by LMT »

Offline LMT

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Re: Free Launch, or Mars Clathrate Mining
« Reply #9 on: 12/27/2017 07:41 PM »
the H20/CO2 economy

Redox Economics

An economy is often based on a redox pair, and methane/oxygen is a great one.  (In contrast, the hydrogen in water is already oxidized, so water's a non-starter, in terms of redox economics.)  Whoever might find and access a hypothetical clathrate deposit would be providing the critical resource for a methane-based redox economy.  Under terms of the U.S. Commercial Space Launch Competitiveness Act, that first-mover is granted control of the clathrate "space resource", to sell its methane at any price the market will bear -- and he does so "free from harmful interference", i.e., government interference.

He only has to demonstrate "recovery", just once, to make the claim.  And he has to be first.  Therefore methods for fast prospecting and fast deployment of a "drilling rig" should be of interest to ambitious parties.

« Last Edit: 12/27/2017 11:37 PM by LMT »

Offline stefan r

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Re: Free Launch, or Mars Clathrate Mining
« Reply #10 on: 12/27/2017 11:59 PM »
The Idea

From “Methane Hydrate on Mars: A Resource-Rich Stepping Stone to the Outer Planets?
Depending on the volumes involved this could be huge.

Many mfg processes (metal smelting, glass and concrete production) are very energy intensive. a large supply of indigenous hydrocarbon fuel radically simplifies the ability of any settlement to expand.

A key question would be wheather this is a continuous process or if its a finite reserve, but just the availability makes a very big change to what it takes to make ISRU viable.

Without an oxygen atmosphere methane [or chlathorate] is not an energy source.

Methane and other hydrocarbons work well as a chemical feedstocks.  Hydrogen should be quite valuable on Mars.

Offline LMT

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Re: Free Launch, or Mars Clathrate Mining
« Reply #11 on: 12/28/2017 04:14 PM »
IIRC SX are talking about using the sort of systems developed for the ISS for O2 production, using CO2 and water to get Methane and O2. With a ready supply of Methane I guess you could skip most of the process and go with water electrolysis, logically starting from the ice that held the Methane to begin with.

Reactor vaporization would give you water vapor for electrolysis, yes.  However electrolysis itself is an energy hog, taking ~16 million Joules for every liter of water dissociated.

Catalytic Conversion of CO2 to O2

Polar CO2 can be obtained in solid form, in winter up north, year-round down south, requiring no energy for compression.  That could be a starting point for efficient conversion to O2.  What are presently the most efficient catalytic methods for conversion of CO2 to O2? 

One example:  A Study on CO2 Decomposition to CO and O2 by the Combination of Catalysis and Dielectric-Barrier Discharges at Low Temperatures and Ambient Pressure

Parameters:  specific input energy (SIE) of 55.2 kJ/L and low temperatures (<115 °C)   
« Last Edit: 12/28/2017 05:47 PM by LMT »

Offline john smith 19

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Re: Free Launch, or Mars Clathrate Mining
« Reply #12 on: 12/28/2017 08:34 PM »
Quote from: LMT
Reactor vaporization would give you water vapor for electrolysis, yes.  However electrolysis itself is an energy hog, taking ~16 million Joules for every liter of water dissociated.

Catalytic Conversion of CO2 to O2

Polar CO2 can be obtained in solid form, in winter up north, year-round down south, requiring no energy for compression.  That could be a starting point for efficient conversion to O2.  What are presently the most efficient catalytic methods for conversion of CO2 to O2? 

One example:  A Study on CO2 Decomposition to CO and O2 by the Combination of Catalysis and Dielectric-Barrier Discharges at Low Temperatures and Ambient Pressure

Parameters:  specific input energy (SIE) of 55.2 kJ/L and low temperatures (<115 °C)   
It's interesting this work comes from Newcastle University in the UK. IIRC CO/O2 was the core proepllants that Reaction Engines looked at for use in their Mars feasibility study "Project Troy," although I believe they also looked at the higher performance (but much hotter) Cyanogen/O2 system.

The obvious attraction is it's an all gas system and is vaible anywhere on Mars even if water is not available, albeit not very quickly. 
« Last Edit: 12/29/2017 05:57 AM by john smith 19 »
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.
So you're going to Mars to seek a better life. What does that mean to you? Always spot a fanbois by how they react to their idols failures.

Offline LMT

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Re: Free Launch, or Mars Clathrate Mining
« Reply #13 on: 12/29/2017 01:07 AM »
Oxygen in the Ice

Some oxygen would be available in the clathrate ice. 

Cosmic rays decompose water ice, producing O2 and H2O2 [Zheng et al. 2006].  Both products are trapped, but H2O2 remains trapped at higher temperatures, up to ~ -130 C [Cooper et al. 2008, Fig. 10].  That temperature is above the persistent temperature of south polar ice, indicating persistent trapping of H2O2 even at the south polar water-ice surface.  Production and preservation of H2O2 are further improved by the presence of dry ice, which acts as an electron scavenger [Moore & Hudson 2000].

Dust grains -- especially olivine -- may deposit additional H2O2 atop growing ice caps [Hurowitz et al. 2007], increasing the H2O2 inventory.  Pulverized minerals have activated surfaces that produce H2O2 in solution.  (This H2O2 may partially explain the oxidizing nature of martian regolith.)  Moreover, the electric fields of dust storms can increase H2O2 production on the grains.  In fact, seasonal variations in martian atmospheric H2O2 concentration have been observed, consistent with the LMD general circulation model, which incorporates dust transport [Encrenaz et al. 2012].

Collection

H2O2 is unstable.  When released via hypothetical reactor chamber-melt, the H2O2 can be quickly decomposed by heat and/or a catalyst.  The catalyst might coat the reactor's hot radiator panels, so that H2O2 decomposes when passing over the radiator.  Thereafter the vapor separator captures and liquefies the freed O2.

Trapped O2 and H2O2 could supply only a fraction of the O2 required to combust the methane released from a clathrate deposit.  It's not enough, but the price is right.

Refs

Cooper, P.D., M.H. Moore, and R.L. Hudson (2008) Radiation chemistry of H2O + O2 ices. Icarus, 194(1): p. 379-388.

Encrenaz, T., Greathouse, T. K., Lefèvre, F., & Atreya, S. K. (2012). Hydrogen peroxide on Mars: observations, interpretation and future plans. Planetary and Space Science, 68(1), 3-17.

Moore, M. H., & Hudson, R. L. (2000). IR detection of H2O2 at 80 K in ion-irradiated laboratory ices relevant to Europa. Icarus, 145(1), 282-288.

Zheng, W., Jewitt, D., & Kaiser, R. I. (2006). Formation of hydrogen, oxygen, and hydrogen peroxide in electron-irradiated crystalline water ice. The Astrophysical Journal, 639(1), 534.
« Last Edit: 12/29/2017 06:04 AM by LMT »

Offline LMT

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Re: Free Launch, or Mars Clathrate Mining
« Reply #14 on: 12/31/2017 06:08 PM »
Methane Self-Delivery

To produce O2 from CO2, plasma systems are competitive with SOXE systems like MOXIE.  However the heat and water vapor of a clathrate mine would support a more efficient method for producing O2:  high-temperature steam electrolysis (HTSE).  O2 from nuclear HTSE could efficiently supplement mined O2, to complete the O2 load required for suborbital methane delivery to crewed facilities.  It's one way a mine could be minimally self-sufficient in O2 propellant, so as to self-deliver methane where needed. 

Hypothetical Scenario

Using previous posts 1 and 2:  Just hypothetically, one might envision two clathrate mines, one near each martian pole.  In this scenario mined ice has 3 wt% CH4 and 1 wt% O2 equivalent.

Each mine aims to produce enough O2 to launch an ITS craft monthly to a crewed facility as distant as the equator.  Each craft loads only enough O2 for the suborbital hop, as it's assumed a larger O2 plant at the crewed facility produces much more O2 from an algae farm etc.  Each CH4 tank launches full, as it's assumed that all CH4 is supplied from the mines.

The suborbital delta-v and propellant requirements are roughly estimated from an application of [Griffin 2004].  For the hop ~230 t of O2 is required, of which ~80 t is released from the ice.  The remaining 150 t is produced in situ. 

Nuclear HTSE

To produce O2, a hypothetical nuclear HTSE plant is considered.  It's quantified crudely by scaling down the modeled INL design [Suk Kim et al. 2016]. 

Open question:  Is there a more efficient HTSE design?

Result

To launch an ITS craft to the equator once every Earth month, the plant allocates only ~900 kW electrical power and ~300 kW heat to O2 production. 

Therefore, at first glance, it seems these particular requirements for power and heat could be met with a set of scaled Kilopower reactors, or other small fission reactors, assuming manufacture is feasible within the roughly 20-year timeframe of interest.  The required plant would be only a small reactor farm.  This farm would itself be only an extension of the pre-existing reactor farm needed for clathrate mining, its own specifics tbd of course.

Hydrogen Option

Hydrogen should be quite valuable on Mars.

The HTSE H2 product could be delivered for use at crewed facilities.  For each 150 t of O2 produced, 19 t of H2 is produced.

Refs

Griffin, M. D. (2004). Space vehicle design. AIAA.

Guerra, V., Silva, T., Ogloblina, P., Grofulović, M., Terraz, L., da Silva, M. L., ... & Guaitella, O. (2017). The case for in situ resource utilisation for oxygen production on Mars by non-equilibrium plasmas. Plasma Sources Science and Technology, 26(11), 11LT01.

Hecht, M., Rapp, D., & Hoffman, J. (2015). The Mars oxygen ISRU experiment (MOXIE).

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