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  • The Martian atmosphere is ninety five percent carbon dioxide, about a few percent nitrogen,

  • a few percent argon, trace amounts of everything else. But there's still a lot of CO2, and

  • so that's probably the most abundant resource on Mars other than dirt. CO2 has oxygen bound

  • in it. And if we can liberate that oxygen from some of that CO2, then we can use it

  • to do something useful. The goal is to pave the way for future human exploration of Mars

  • by demonstrating the ability to generate oxygen. That's where the magic happens is inside that

  • box. NASA is set to launch its next rover to the red planet in 2020. Stacked inside

  • are seven science instruments, six of which are focused on sample analysis like this SuperCam

  • and a spectrometer called PIXL that'll measure chemical signatures inside Martian rocks.

  • And this box getting lowered inside the belly of the rover is MOXIE, or the Mars Oxygen

  • In-Situ Resource Utilization Experiment. It's got an agenda separate from the others, and

  • that's to make oxygen on Mars for the first time. Well, at least in real life. In the

  • Martian, there was something that was called the oxygenator. If the oxygenator breaks,

  • I'll suffocate. If the water reclaimer breaks, I'll die of thirst. So we jokingly refer

  • to MOXIE as the oxygenator. It's unclear in the movie what technology the oxygenator is

  • actually using, but it's very likely that it would be something like MOXIE but scaled

  • up. MOXIE uses a technology called solid oxide electrolysis. It works a lot like a reverse

  • fuel cell where instead of putting in a fuel and getting electricity out, we can put electricity

  • in and electrolytes and basically get a fuel and an oxidizer out. On the outside the rover,

  • we have a small box with a filter. The filter is to make sure that we don't draw in any

  • dust from the Martian atmosphere into our system, because the next thing in the path

  • is a scroll compressor. The scroll compressor takes this low pressure Martian gas from the

  • atmosphere and compresses it and brings it up to something closer to Earth's atmospheric

  • pressure. Because the next thing that we do is we run it into this thing. We call this

  • our solid oxide electrolysis stack and it is basically a layer cake of a bunch of metal

  • plates, which are the dark green things. And then these light colored layers are thin ceramic

  • cells that have particular chemical properties where at high temperature, they can conduct

  • electricity using oxygen as the charged carrier. We heat this guy up to about eight hundred

  • degrees Celsius. You have oxygen ions on one side and you apply a voltage, then you can

  • selectively dry the oxygen through the ceramic membrane and separate it out from whatever's

  • on the other side. It goes through a set of sensors very much like these sitting here

  • on the table in front of me. And we measure what fraction of CO2 is there. We put CO2

  • in here. Oxygen comes out here. And the waste product, which is a mixture of CO and carbon

  • monoxide and unreacted CO2 comes out here. It's gold because we were concerned that

  • MOXIE itself would run hotter than everything else around it. And we wanted to make sure

  • we didn't impact any of the nearby electronics boxes inside the rover. And so, gold has very

  • low emissivity, so it doesn't radiate heat effectively. This particular chemistry process

  • is sort of unique to Mars in its applicability, and also the packaging and how we actually

  • build this system to survive launch and get to Mars. No one has ever done anything like

  • this. MOXIE is going to make about six grams per hour of oxygen. It's not very much. It's

  • about enough to keep a small dog alive. We don't have the resources available on the

  • rover to run MOXIE for long periods of time continuously because a lot of the rover energy

  • has to be used for other science that they want to do. We will probably run MOXIE at

  • roughly once every two months. The goal for us is to sample different environmental conditions

  • on Mars. So day versus night, summer versus winter, dust storm versus not dust storm...to

  • assess how the technology behaves in response to these changing environmental conditions.

  • What might happen in the future really depends on the technology that NASA decides to go

  • with on Mars. If you're assumption is that you only have the CO2 in the atmosphere available,

  • then you'd have something like MOXIE scaled up by about a factor of two hundred. You'd

  • launch it and deliver it to Mars about two years before humans set foot there. It would

  • have a bunch of supporting equipment like a power system and a storage system, and it

  • would sit for two years and just generate oxygen and collect it, and then it would be

  • ready for use by the humans when they show up two years later. It's really exciting for

  • me to be able to build something that's going to land on another planet. I hope that it's

  • gonna work the way we expect it to. And that paves the way for future human exploration

  • in the not too distant future.

The Martian atmosphere is ninety five percent carbon dioxide, about a few percent nitrogen,

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B1 oxygen co2 rover martian electrolysis atmosphere

NASA’s Gold Box Will Make Oxygen on Mars

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    林宜悉 posted on 2020/03/30
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