back to article How this Mars rover used its MOXIE to convert CO2 into precious oxygen

The oxygen-generator onboard NASA's Perseverance rover, which has repeatedly extracted the vital gas from the Martian atmosphere in tests, has been detailed in a scientific paper published this week. About 95 percent of the Martian atmosphere is made up of carbon dioxide, and very little is oxygen. If we're to have long-term …

  1. Bitsminer Silver badge

    "If you can make it here, you can make it anywhere."

    Frank never knew.

    1. Irony Deficient

      Frank never knew.

      I’m not sure about that:

      … let me see what spring is like

      On Jupiter and Mars.

      1. Neil Barnes Silver badge

        Re: Frank never knew.

        But aren't the blue eyes a characteristic of Dune? Where it's water that's the problem, not loose oxygen?

        1. Irony Deficient

          But aren’t the blue eyes a characteristic of Dune?

          If I recollect the books correctly, blue scleras were an acquired characteristic of spice users, few of whom actually lived on Dune, and was unrelated to the amount of surface water on Dune.

          Ol’ Blue Eyes had blue irises rather than blue scleras.

          1. that one in the corner Silver badge

            Re: But aren’t the blue eyes a characteristic of Dune?

            "Few of whom lived on Dune"

            The Fremen keep the secret of their numbers from the offworlders.

  2. Ribfeast

    Don't you need a bunch of nitrogen to make it breathable too?

    Impressive achievement!

    1. John Brown (no body) Silver badge

      Not really, other mixes and O2 partial pressures are available. We don't process nitrogen when we breath it in and out, so it's not depleted if used as a "filler" in a breathable atmosphere. It is, however, used by plants, so if we are going to be growing food there, then there will be nitrogen depletion by the plants and any subsequent human consumption. But then we shit it out and can grow potatoes in the resultant excretions as shown by a certain documentary :-)

      1. JimmyPage

        Er, don't plants get their nitrogen

        from the soil ?

        1. Spazturtle Silver badge

          Re: Er, don't plants get their nitrogen

          Both, some plants can fix nitrogen straight from the air (legumes for example), rain also picks up nitrogen as it falls through the atmosphere and plants can absorb that when they suck up the water, and then there are the liquid and solid forms of nitrogen that plants take up from the soil.

          1. Vikingforties

            Re: Er, don't plants get their nitrogen

            Lightning is an important generator of nitrogen that plants can consume too.

      2. Caver_Dave Silver badge

        Cave diving reference

        Narcosis and the bends are a problem on deep and complex dive profiles, mainly caused by Nitrogen.

        Heliox and other gas mixtures are used to reduce the problems by reducing the Nitrogen (but also have their own problems).

        Famous quote from Dr Maurice Cross at the Fort Bovisand Diving Diseases Research Centre when cave divers Rob Palmer and Rob Parker first enquired about using rebreathers, complex dive profiles etc. (something well beyond even special forces at the time, and even now if the Thai cave rescue is anything to go by) "he's like someone who makes love on a bed of nails - he doesn't want a cure, just a Tetnus jab" [from memory so may be slightly wrong in detail]

      3. tiggity Silver badge

        Though pure O2 is fatal (not to mention fire hazard)

        Too much CO2 in the mix causes lots of nastily unwanted effects that can be fatal too.

        So, a filler of some sort is needed

        1. midgepad


          It is partial pressures, not percentage.

          Some inert gas is good, to stop absorption atelectasis - small portions of lung losing gas and sticking shut.

          But given the 3psi of O2 you'll be fine.

          Given 30 psi of O2 you'll convulse.

  3. Anonymous Coward
    Anonymous Coward


    But cant they just hold their breaths?

    1. Michael Wojcik Silver badge

      Re: Interesting

      Elon wants to go, and we know he's not capable of keeping his mouth shut.

    2. Anonymous Coward
      Anonymous Coward

      Re: Interesting @AC re. breaths.

      I'm sorry. Totally irrelevant sidetrack surfaced from my memory.

      Doctor to young patient (while holding a stethoscope to her chest): "Big breaths"

      Patient (with a lisp) to doctor: "Yeth, and I'm only thixtheen"

      It's stupid how associative memory works! Possibly from a Carry-on film involving Barbara Windsor.

  4. Potemkine! Silver badge

    I learned in other article that MOXIE produced as much oxygen per day as a small tree.

    This is a huge achievement. Congrats to the MIT, and to the NASA to bring it there.

    == Bring us Dabbsy back! ==

  5. hekla

    You need the nitrogen

    Nitrogen in the atmosphere is a fire suppressant, a pure O2 atmosphere will make many things that are same here on Earth into bombs on a Martian site if it uses pure O2. Also you cannot use CO2 as a filler as it is toxic at about .1% (need to verify that number) of the atmosphere.


    The other question is how much CO2 is in the Martian atmosphere and how quickly will an active transport & biosystem deplete it.

    1. hekla

      Re: You need the nitrogen

      Google says 5000 ppm is dangerous for extended exposure and 40 000 ppm is immediately fatal.

    2. hammarbtyp

      Re: You need the nitrogen

      Well making things blow up in a controlled manner i.e Rockets is the purpose of the experiment, but in terms of human habitation, Nitrogen is 2.8% of the Martian atmosphere. OK its not the 70% of Earths, but extraction and concentration would be relatively straight forward by freezing the air (not a big issue on Mars).

      The nitrogen would also be useful to make Ammonia if we wanted to go all Matt Damon

      In terms how long would it take to deplete the atmosphere of CO2? A vast, vast amount of time despite the relative low density on Mars, and that is before you factor in the CO2 sublimed at the poles. Also we are only borrowing the Oxygen. Once it is burnt or breathed in it becomes CO2.

    3. Anonymous Coward
      Anonymous Coward

      Re: You need the nitrogen

      There's nitrogen in the atmosphere there, the composition is apparently 95% carbon dioxide, 2.7% nitrogen, 1.6% argon and a few other bits. I'd imagine pulling out the CO2 and adding about 20% oxygen would leave it breathable to humans. Though the "other bits" could be a factor, depending on what they are.

    4. Charlie Clark Silver badge

      Re: You need the nitrogen

      The lack of an ionosphere, low gravity and magnetic field make Mars uninhabitable and you're worrying about complementary gases?

      1. hammarbtyp

        Re: You need the nitrogen

        well the lack of ionosphere is caused by the lack magnetic field, and because you are unlikely to be sun bathing on the surface it is probably not a huge issue and there are ways to protect habitation such as digging down

        Mars gravity is low( third of earths), but it is still relevant. Whether the health effects of zero gravity would be the same for this is unknown. However both of these effects are more pertinent to the issues of actually getting there

        However neither of these makes Mars uninhabitable, just very challenging and it is still probably the 2nd most hospitable place in the near universe

        Whether we should go all Elon Musk on the place is another question, but there is no doubt it would be achievable with enough time and resources

        1. Charlie Clark Silver badge

          Re: You need the nitrogen

          However neither of these makes Mars uninhabitable, just very challenging and it is still probably the 2nd most hospitable place in the near universe

          Firstly, let's not learn to fuck up the most habitable place before we start on the rest. I guess the term habitable is pretty flexible but even if some kind of semi-permanent structure would be possible on Mars, you're still going to struggle to get any of the resources to sustain life for any period of time given all the other problems.

          Some of the moons of the gas giants seem to have more to offer, which is why missions are planned for them, though these will be purely scientific for the forceable future. Even with an intact atmosphere, reasonable gravity and possibly even liquid water, there lots of other hazards of living in orbit around a gas giant. But there are also things to be learned about being able to do it for future missions to other solar systems, should we ever be able to build spaceships that can travel fast enough.

    5. midgepad


      Ww2 submarines had episodes of up to 4%CO2.

      Gradual rise in prolonged hiding.

      People didn't feel well, but they didn't die of that.

  6. Charlie Clark Silver badge

    What about the carbon monoxide

    Catalytic reduction of CO2 to CO is well known but the second part of this is to hydrate the CO to get hydrocarbons. CO is a magnitude more poisonous than CO2

  7. J.G.Harston Silver badge

    How effective is this compared to room-temperature water electrolysis?

    1. sitta_europea Silver badge

      "How effective is this compared to room-temperature water electrolysis?"

      Good question, and with water electolysis you get hydrogen as well!

      1. Charlie Clark Silver badge

        Remember, this is on Mars…

    2. Charlie Clark Silver badge

      2H2O -> 2H2 + O2 is not meaningly comparable with 2CO2 -> 2CO + O2 but if you really want to, the higher temperature and pressures involved tell you all you need to know.

    3. midgepad

      Very, if you have

      CO2, and don't have water.

  8. Auntie Dix

    MOXIE: A Clever Toaster That Cannot Make Toast

    These experiments are interesting, but there is way too much hype about putting man on Mars.

    The reality for the foreseeable future is that it will be a death sentence for any first pioneer, should he even reach its soil.

    Let us shift focus back to our mostly unexplored moon. We have not even managed to reside there!

    We are nowhere near creating Moonbase Alpha of "Space: 1999," let alone working side by side cheerfully in Rudi Gernreich's form-fitting, polyester outfits.

    Show me a fleet of Eagles before you spend my tax dollars on recipes for Martian poop potatoes.

    1. Snowy Silver badge

      Re: MOXIE: A Clever Toaster That Cannot Make Toast

      Speaking of soil, Martian soil is toxic, due to relatively high concentrations of perchlorate compounds containing chlorine. The levels detected in the Martian soil are around 0.5%, which is a level considered toxic to humans. These compounds are also toxic to plants.

      Another problem with fine Martian dust has long been recognized by NASA. A 2002 study warned about the potential threat, and a study was carried out using the most common silicates found on Mars: olivine, pyroxene and feldspar. It found that the dust reacted with small amounts of water to produce highly reactive molecules that are also produced during the mining of quartz and known to produce lung disease in miners on Earth, including cancer (the study also noted that lunar dust may be worse

      Dust is also a problem as it is very fine and charge so it will stick to everything and get everywhere.

    2. zuckzuckgo Silver badge

      Re: MOXIE: A Clever Toaster That Cannot Make Toast

      > it will be a death sentence ...

      That is true of all life on any planet. Although granted the quantity and quality of life on mars is unlikely to meet my personal standards any time soon.

  9. Korev Silver badge

    > Oxygen is needed for breathing

    Thanks, I didn't know that...

  10. Pen-y-gors

    And energy?

    What is the energy input? Heating things to 800C needs quite some oomph. How good are solar panels and wind turbines on Mars?

    == Bring us Dabbsy back! ==

    1. Charlie Clark Silver badge

      Re: And energy?

      Solar is reasonable as the various missions have shown, wind is pretty useless due to the lack of atmosphere: there are winds but they windmills would have to be unfeasibly large to get anything from them.

      1. Ruisert

        Re: And energy?

        Storms on Mars are known to have very high wind velocities, which should enable wind power to be harnessed. If they can fly a drone on Mars, they can make turbines that work. It's just a matter of materials and design. Larger designs are possible, given the difference in gravity.

        And, if pure carbon can be extracted from this, or another process, it's only a few steps away to produce carbon fiber for construction.

        1. Snowy Silver badge

          Re: And energy?

          Given the pressure of the atmosphere is very low on Mars not sure that even a fast wind is going to produce very much power.

          The reason the drone can fly is the blades rotate very fast.

        2. Charlie Clark Silver badge

          Re: And energy?

          It's not velocity you want for wind power, it's momentum: the atmosphere is too thin.

      2. Snowy Silver badge

        Re: And energy?

        Them panels are going to need to be about double the size they would need to be on Earth.

        Mars is about 1.5 AU from the sun while Earth is about 1 AU, which gives about 44%.


        1. Charlie Clark Silver badge

          Re: And energy?

          True, but as long as you don't want to heat the place, that's not too bad and certainly better than the alternatives.

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