[HN Gopher] Plasma reactors could create oxygen on Mars
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Plasma reactors could create oxygen on Mars
Author : rntn
Score : 62 points
Date : 2022-08-16 19:37 UTC (3 hours ago)
(HTM) web link (www.science.org)
(TXT) w3m dump (www.science.org)
| linuxftw wrote:
| We're never going to colonize mars, every penny spent on mars is
| wasted.
| cryptodan wrote:
| This is how DooM started.
| colechristensen wrote:
| Isn't there plenty of oxygen which could be much more simply
| burned out of mars rocks? Place is covered with fine dust that's
| almost entirely metal oxides. I'm thinking concentrated solar to
| liberate the oxygen and produce a nice metal building material
| that could be refined to base metals for all sorts of things.
| hinkley wrote:
| On earth a great deal of life's variety happens at the
| boundaries, such as in tidal zones and estuaries. There are no
| oceans on Mars but there is also very little atmosphere. I
| suspect we will want to engineer our oxygen producing equipment
| to make estuaries and tidal zones for atmosphere, where there
| is either a steady stream of atmosphere, or daily pulses that
| push life to adapting to temporary deficits and surpluses of
| resources.
|
| Later on that could be accomplished just by routing the exhaust
| down into the canyons, but early on that may have to go through
| greenhouses, which either vent above a certain pressure or
| aren't quite hermetically sealed.
| ortusdux wrote:
| I've always thought this was the obvious choice. I wonder what
| the logistical issues are. As a bonus, you get pure iron as a
| byproduct, which would be worth it's weight in gold as a
| building and additive manufacturing resource.
| colechristensen wrote:
| If you just roast common Martian soil you don't just get iron
| but many metals mixed together (the three mars landers tested
| and got pretty similar results at a high level)
| nickpinkston wrote:
| That's my intuition too, though given's gene-h's citation [1]
| in this thread, there may be an interesting analogy between
| water evaporation and reverse osmosis, as the proposed tech
| creates a plasma and the oxygen diffuses through a membrane
| (like osmosis tech). We know that reverse osmosis is the more
| efficient tech compare to evap, so who knows.
|
| [1] https://aip.scitation.org/doi/10.1063/5.0098011
| PaulHoule wrote:
| "Method X could create oxygen on (Moon|Mars)" headlines drive me
| nuts.
|
| Before we sent astronauts to the moon successfully we discovered
| the hard way that astronauts are likely to die if they breathe
| pure O2.
|
| https://en.wikipedia.org/wiki/Apollo_1
|
| Future Apollo missions mitigated the danger of fires by being
| really careful about the materials in use, but that's not a good
| answer for long term missions, particularly if the astronauts are
| going to conduct industrial activities such as in-situ resource
| utilization.
|
| If you want to make breathing gas on Mars, O2 covers 20% of it,
| the rest of it is going to be an inert gas like Nitrogen, Argon,
| Helium or SF6.
|
| Of course every method of producing O2 in space works by
| separating O from something else and the "something else" is
| likely to be useful, such as H2, C, Al, etc.
| mpweiher wrote:
| Apollo continued to use pure oxygen once in space, even after
| the Apollo 1 fire.
|
| https://www.popsci.com/why-did-nasa-still-use-pure-oxygen-af...
| teraflop wrote:
| That seems like an extremely pedantic complaint.
|
| Sure, the breathing gas for a crewed mission or habitat would
| need to include an inert gas as well as oxygen. But oxygen is
| consumed during respiration and the inert gas isn't, so oxygen
| will be needed in much larger quantities, so in-situ production
| is a much more pressing problem.
| PaulHoule wrote:
| You are probably recycling the CO2 from the astronauts breath
| which is easier than cracking it from the air. Also many
| practical breathing systems (especially for spacesuits) leak
| some of the inert gas for cooling and other purposes.
|
| The real thing you'll need O2 for is an oxidizer for fuel but
| of course you need to make fuel too.
|
| If you are interested in making anything interesting such as
| large plastic sails or small biospheres nitrogen is the big
| missing piece of the puzzle right now in the moon, mars and
| asteroids.
| ben_w wrote:
| > recycling the CO2 from the astronauts breath
|
| It's literally exactly as difficult as cracking out from
| the air, because breath is in fact made from air.
| sigstoat wrote:
| being extremely generous, and assuming he meant "martian
| atmosphere" when he said "air", it _might_ be a bit more
| challenging (depending on your process and what you've
| got available) to convert the CO2 at 0.095 PSI into O2,
| than it would be to pull the CO2 out of ~14.7 PSI human
| exhalations and convert it to O2.
|
| seems like the kind of thing where there is a bunch of
| engineering that could be productively done.
| MichaelCollins wrote:
| CO2 needs to be scrubbed/vented out of the breathable
| atmosphere. Even if there is abundant of oxygen anyway, too
| much CO2 will make people feel dizzy and confused, cause
| splitting headaches, increased heart rated, reduced senses,
| and eventually death. CO2 can't take the place of inert
| nitrogen in a breathable atmosphere, that much CO2 in the
| air just isn't compatible with human life.
| MichaelCollins wrote:
| A major contributing factor to the Apollo 1 fire was they
| didn't merely have a pure oxygen atmosphere, but a
| _pressurized_ pure oxygen atmosphere. Pressurized above 1
| atmosphere, for testing purposes. In space they would have
| operated with a substantially lower pressure; I believe about 1
| /5th of atmospheric pressure. A low pressure pure oxygen
| environment is still a fire hazard relative to regular air with
| the same partial pressure of oxygen, but it's not nearly as
| dangerous as a pressurized oxygen atmosphere.
| basicplus2 wrote:
| What would they do with all that toxic CO??
| fnordpiglet wrote:
| Huff it to get high
| lovemenot wrote:
| Assume you were thinking of nitrous oxide N2 O.
|
| C O is deadly when inhaled
| LeifCarrotson wrote:
| Toxic to who or to what?
| PaulHoule wrote:
| Make organic chemicals. See 'C1 chemistry'. CO is one of my
| favorite substances to get in designing chemical factories in
| space.
| jscipione wrote:
| There's a heck of a lot more CO2 in Venus' atmosphere than there
| is in Mars'.
| John23832 wrote:
| Great. Now let's deal with the carcinogenic soil.
| jmyeet wrote:
| Two things:
|
| Producing materials from other materials such as extracting
| oxygen from various compounmds is ultimately an energy problem.
| Better processes might reduce the ultimate cost by reducing the
| capital cost or reducing the running cost. For example: we can
| make hydrocarbons from the atmosphere. It's just uneconomic
| because of the energy cost.
|
| The energy source itself presents issues. If you need a $50
| billion fusion reactor that takes 20 years to build and a
| thousand people to maintain then that's a problem to bootstrap on
| Mars.
|
| I personally believe that on Mars, much like on Earth, the future
| is solar. Solar has a lot of benefits on places like Mars. It's
| the only form of power generation that reduces electricity
| directly rather than boiling water and turning a turbine.
|
| So mars still has the two big problems it always has had:
|
| 1. It's further from the Sun so solar is less effective. This
| just increases the cost of energy, ultimately. Of course,
| there'll occassionally be a months-long dust storm that'll stop
| you producing any power or just a shorter one that covers all
| your panels in dust; and
|
| 2. What are you going to do with this oxygen? You're going to be
| living underground because living above ground exposes you to
| radiation and the Martian surface itself is toxic (eg
| perchlorates). If you're living underground anyway, why are you
| living on Mars instead of the Moon?
|
| Mars just makes zero sense to colonize.
| [deleted]
| [deleted]
| smm11 wrote:
| Let's put Arnold on it.
| S_A_P wrote:
| Could the same thing be used to remove carbon dioxide from
| earth's atmosphere?
| Johnny555 wrote:
| The reaction described in the article says that it strips an
| oxygen molecule from carbon dioxide, creating carbon monoxide.
|
| CO typically only lasts for a few months in the atmosphere, but
| only because CO molecules react with oxygen, forming CO2.
|
| So I think no, this could not be used to sequester CO2 from the
| atmosphere.
| eggy wrote:
| Douglas Quaid discovered this in the 1990s on Mars!
| trhway wrote:
| SpaceX will need to split CO2 into CO and O2, H2O into H2 and O2,
| combine the firsts into methanol and pour all this into the
| Starship tanks for the Earth bound trips. That means that they
| will probably bring nuclear reactor(s) there (my hope though is
| that Musk will decide to do to fusion that he had already done to
| EV, space, etc.). O2 for humans will be just a noise (also
| greenhouses for food production will probably generate O2 enough
| for humans).
| tsimionescu wrote:
| > my hope though is that Musk will decide to do to fusion that
| he had already done to EV, space, etc.
|
| Fusion power doesn't need the kind of incremental advances and
| smart marketing that Musk's companies have benefitted from, it
| needs huge fundamental advances in science and engineering.
|
| That said, by the time anyone actually tries to establish any
| kind of base on Mars, we may well have figured fusion (my money
| is still on ITER's follow-ups, the DEMO plants, being the first
| to actually do anything, in 2050 at the earliest). Musk's
| "plans" for Mars are just part of his pretty smart marketing /
| outright lying to bolster his companies.
| systemvoltage wrote:
| Although something tells me that Fusion would be a solved
| problem in about 18 months if we were in a wartime and have
| all hands on the deck. I am joking only slightly.
| trhway wrote:
| >Fusion power doesn't need the kind of incremental advances
| and smart marketing that Musk's companies have benefitted
| from, it needs huge fundamental advances in science and
| engineering.
|
| It is systems engineering - take the available science and
| engineering and combine into an actually working thing. That
| is exactly what we need with fusion today.
| JumpCrisscross wrote:
| > _take the available science and engineering and combine
| into an actually working thing_
|
| This doesn't describe the present situation. For example,
| high-temperature superconducting magnets open design space
| which simply didn't exist a decade or two ago.
| elihu wrote:
| Nuclear has the problem that you somehow need to hoist a
| reactor from the Earth into space, and putting nuclear
| materials makes a lot of people nervous. (What happens if the
| rocket launch fails and scatters radioactive debris?)
|
| An alternative is to gather the reactor fuel on Mars, but that
| sounds like a difficult undertaking.
|
| I think the expectation is that the energy needed to make
| methane on Mars will be provided by a lot of solar panels.
|
| (I would be curious to know how the math works out. For
| instance, if you send a Starship fully loaded with solar panels
| to Mars and spread them out on the ground, how long will it
| take those solar panels to gather enough energy to make enough
| methane to return the rocket to Earth? Is it one year? 10
| years? 100 years?)
| trhway wrote:
| The amount of highly enriched U and Pu that has already been
| put into space is at least several hundred of kilograms
| across at least 10+ of launches. And reliability of SpaceX
| launches is highest in history of human space programs.
|
| My bet is on nuclear vs solar as the nuclear is the next
| rocket engine type after chemical and will loose the
| dependency on launch windows and shorten the trip time.
| elihu wrote:
| The safety risk isn't necessarily an insurmountable
| obstacle; I could imagine the U.S. government being more
| likely to approve sending a nuclear reactor into space if
| it was NASA that was asking as opposed to a private
| company, but either way it's more of a political problem
| than a technical one.
|
| Nuclear rocket engines are tricky. Nuclear reactors don't
| actually work very well in space because there isn't any
| convenient way to get rid of the excess heat. A vacuum is a
| very good insulator, so usually your only option is just to
| radiate it away as infrared light.
|
| With a rocket there's another option which is to transfer
| all the heat to the reaction mass you're expelling out the
| back of the ship. That sounds like a hard engineering
| problem though.
|
| Using a reactor on the Mars surface is a lot more
| straightforward because you can use the local air and
| ground to transfer heat. And since Mars is so cold, you
| might even get better steam generator efficiency there than
| on Earth, where the ambient temperatures are higher.
|
| One of the hopes with fusion is that if it pans out it
| might be reasonable to send a fusion reactor to Mars since
| you wouldn't need to send radioactive fuel rods. In fact,
| maybe the first practical fusion reactors will be used on
| Mars before they're used in more than a demonstrative
| capacity on Earth because they fit a very specific need,
| there are barriers to using the alternatives, and cost per
| kw/h isn't the most important constraint.
| alex_young wrote:
| There are plenty of nuclear reactors already in space. The
| Voyager probes are famously powered by radioisotope
| thermoelectric generators, and even the Perseverance lander
| mentioned in the article is powered by one. Full list here: h
| ttps://en.wikipedia.org/wiki/List_of_nuclear_power_systems_..
| .
| aqme28 wrote:
| Those are much much smaller than the nuclear reactors that
| parent comment is talking about. A totally different beast.
| elihu wrote:
| Interestingly the biggest reactors (mostly 2kw and a few
| 5kw) were deployed by the Soviet Union. Presumably they
| just didn't care about the safety risks.
|
| The risks weren't purely theoretical either. They had one
| nuclear-powered satellite that re-entered over Canada.
|
| https://en.wikipedia.org/wiki/Kosmos_954
| PaulHoule wrote:
| On mars you have a day not too different from ours and solar
| looks attractive. On the moon you really need nuclear because
| the night lasts two weeks. It is so bad people are thinking
| about reversing O'Neills idea and microwave beaming power
| from the Earth to the Moon.
| rdevsrex wrote:
| Couldn't we just use low enriched uranium for that? And as
| long as you aren't actively powering it up on takeoff, even
| in an accident, how radioactive would it be?
| somecommit wrote:
| Should we blast a giant hole into Mars?
| https://www.youtube.com/watch?v=RnRzsQOZSfQ
| bambax wrote:
| Interesting. So maybe the asteroid that killed the dinosaurs
| was an alien attempt to make earth habitable for them.
| knodi123 wrote:
| And it worked. And we are them. Cue intro theme music....
| elihu wrote:
| That was sort of how C.S. Lewis imagined Mars in Out Of The
| Silent Planet, before we really had a good idea of what Mars
| was really like. Most of the planet was unlivable without an
| air supply, but the valleys trapped enough air for plant and
| animal life to thrive.
|
| If one were to make a hole like the one described in the video,
| I wonder how much that would affect the atmospheric pressure on
| the rest of Mars?
| Taniwha wrote:
| mmmm O2+2CO great to breathe ..... to be useful they're going to
| n eed something that separates out ALL the carbon monoxide
| gene-h wrote:
| Here's a link to the paper which this article is about:
| https://aip.scitation.org/doi/10.1063/5.0098011
|
| Using plasmas is interesting for ISRU because they may work at
| Mars ambient atmospheric conditions. I'm quite surprised that
| this plasma reactor approach is more energy efficient than the
| solid electrolysis technique used by the MOXIE experiment.
| vlovich123 wrote:
| Needing to lift all the materials into space from Earth seems
| energy intensive. On the other hand, maybe we'll have fusion-
| based rockets in the future where the energy cost to escape
| Earth's gravity well isn't as important. You'll still have
| potentially two planets worth of needs to support. I know that
| the various space companies are looking at asteroid capture. I
| wonder if it makes sense to just smash some of those into Mars
| before it's inhabited. Yes it potentially destroys scientific
| data but that risk can be managed vs the benefit of having
| easily-accessible building materials on Mars to build large-scale
| industrial equipment / housing if we get serious about colonizing
| Mars.
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