EPISODE 71: MARS OXYGEN IN-SITU RESOURCE UTILIZATION EXPERIMENT

Transcript

Mike Hecht: What MOXIE is doing is transforming carbon dioxide into oxygen that could be used, yes, for astronauts to breathe someday, but more importantly, to provide the oxygen to burn fuel in an ascent vehicle when we’re ready to take our first crews of astronauts home from Mars.

This technology works, it’s reliable and it’s going to be extraordinarily cost-effective.

Deana Nunley (Host): Welcome to Small Steps, Giant Leaps, a NASA APPEL Knowledge Services podcast where we tap into project experiences to share best practices, lessons learned and novel ideas.

I’m Deana Nunley.

An oxygen generator on Mars was the stuff of science fiction – until this year. The MOXIE technology demonstration aboard NASA’s Perseverance Mars Rover is generating oxygen on the Red Planet and helping pave the way for human missions on Mars.

Our guest today is Mike Hecht, the Associate Director for Research Management at MIT’s Haystack Observatory, and the MOXIE Principal Investigator.

Mike, thanks so much for joining us on the podcast.

Hecht: It’s a pleasure.

Host: What is MOXIE?

Hecht: What is MOXIE? Of course, MOXIE is pluck and spirit, but I don’t think that’s what you mean.

Host: But I do love the name. I absolutely love the name.

Hecht: Well, the name, to digresses for just a moment. MOXIE was in the era — I grew up in the Boston area — the soft drink of choice. It’s still around. It was invented in Lowell, Massachusetts, just a few miles from the observatory where I work. And that’s where the expression MOXIE came from. So, that’s a local product.

But in this case, it stands for the Mars Oxygen ISRU Experiment. Yes, we’ve embedded an acronym in another acronym. That’s actually an homage to someone else who did that on a previous version. But the I then stands for ISRU, which is in-situ resource utilization, which means essentially living off the land. It means somehow transforming the resources that you find to put them to work for you. And in this case, the resource that we’re looking to transform is the air, the very air itself. We are in this case, making oxygen out of thin air. The air is very thin, about 1 percent of the amount of air on Earth. But it’s almost entirely carbon dioxide on Mars.

It’s over 95 percent carbon dioxide. So what MOXIE is doing right now on, well, not at this moment, but right now on this mission is transforming carbon dioxide, a local resource readily available just by inhaling, transforming it into oxygen that could be used yes, for astronauts to breathe someday, but more importantly, to provide the oxygen to burn fuel in an ascent vehicle when we are ready to take our first crews of astronauts home from Mars, sometime 15 or 20 years in the future. So, MOXIE is of course, a small prototype. We’re not ready to place a full-scale system on Mars. We don’t have the space. We don’t have the power to do that. But we’re demonstrating that this all works. We can be like a little mechanical tree on Mars and transform carbon dioxide to oxygen.

Host: How does the technology work?

Hecht: Very well, thanks.

Host: (laughter)

Hecht: The technology is actually very similar — it may be identical — to that of a fuel cell. ‘And what,’ you say, ‘A fuel cell doesn’t do that. A fuel cell makes electricity.’ Now we’re using a lot of electricity. And what a fuel cell does is it takes a fuel and an oxidizer and combines them to make some stable molecule like CO2. We’re taking apart the CO2. How can that be the same thing? Well, it turns out it is the same thing. You just run the voltage in the opposite direction and the whole reaction reverses itself.

So, you put in energy, you put in carbon dioxide, and what you get out is CO and oxygen. Now, the type of fuel cell we’re talking about here is a very common type, particularly for CO2. For hydrogen fuel cells, you often have something different that’s made out of a plastic membrane, but for other purposes you often have what’s called solid oxide electrolysis, which is a ceramic, high temperature ceramic. And in fact, MOXIE operates at 800 degrees centigrade in a little oven to heat up the ceramic to get it to work as an electrolysis membrane — in other words, a fuel cell — and run this process in reverse that produces, and this is important, it takes carbon dioxide and produces oxygen and carbon monoxide. So a CO2 molecule, you pull up one oxygen atom and you leave behind CO. Why is that important? Well, if we took both oxygen atoms off, we would have carbon. And carbon would coat the ceramic pieces and they wouldn’t work anymore. So, a good part of what we have to worry about in practice in operating MOXIE is to make sure we don’t go too far in this reaction and start laying down carbon. So that’s kind of the technology.

It’s a fuel cell technology, but of course, like any technology, that makes something, like any factory or any plant, the part that’s turning carbon dioxide into oxygen is only a small part of the full system. And another major part for example, is the part that simply sucks in the air and compresses it to a density where we can do something practical with it. So there’s a whole different compressor technology, which kind of looks like a compressor you’d use on Earth. But as you probably know, you may be able to buy a little compressor at your local hardware store, but making it run on Mars, that’s a whole different beast.

Host: What have you been able to accomplish so far since landing on Mars aboard Perseverance in February?

Hecht: We have turned on MOXIE a number of times to do different tasks, but the ones that people care about are the ones where we actually go through a full cycle, heat it up and produce oxygen. We have done that five times since we’ve landed. So roughly once a month. We landed in February.

We have been able to produce little bits of oxygen by the standards of what we hope to do someday. So maybe 200 times less. And what does that mean in practice? We’ve been able to make up to about eight grams per hour. You and I talking are probably using 20 grams an hour. So, it’s enough to maybe keep a small dog alive. It’s also about what a modest sized tree in your backyard might produce.

So, it’s a scale model, but each time we run, we spend a couple of hours warming everything up, about an hour making oxygen, and we produce somewhere between five and 10 grams of oxygen, which might keep us alive for 10 minutes.

The reason we don’t run all the time is that this takes a tremendous amount of energy. There are lots of experiments on the Rover. We have driving to do. We have core samples to take. And when MOXIE runs, nothing else runs that day. We drain the batteries and then the Rover has to sit and recharge its batteries for a while before anybody else runs.

So, we’ve had our chance to run about once a month, and each time we’ve gotten a little bit more aggressive with the oxygen. We’ve gone under a little bit harsher conditions. For example, we started in the middle of the night. Then we ran in the daytime where the air is even thinner. The air is even thinner than at night. And we’ve done some more complicated experiments where we change the temperature of the stack, or we hold the oxygen production rate constant, but we vary the speed of the compressor coming in. Each time to learn something specific about the system.

Host: Are you seeing indicators that the technology is helping pave the way for future missions to live off the land?

Hecht: We certainly hope and expect. And in fact, the whole reason we’re doing this is to build confidence and both build confidence and build awareness. And thank you for helping us build awareness by the way, that this technology works, it’s reliable and it’s going to be extraordinarily cost-effective. And the reason I say that is that what MOXIE is for isn’t really what you’d think. It’s not so much to provide oxygen for our astronauts to breathe. An astronaut typically uses a kilogram a day. So over the course of a year four astronauts are going to use a ton of oxygen say.

But if we want to lift them off the planet to come home, we’re going to need something like 27 tons of oxygen — much, much more. So, that’s our focus. Now, if we had to bring the 20, 25 or 27 tons of oxygen from Earth, we’d have to get the 15 times that amount of weight to orbit. And we’re talking about multiple missions, all coordinated, all bringing big tanks of oxygen to Mars at the same time, and combining them. Horrendously complicated, horrendously costly. And that’s a very compelling argument to a program manager who’s trying to figure out how to get people to Mars.

Host: Well, what will it take to extend the MOXIE design to a full-scale operational system?

Hecht: The biggest challenge to extending MOXIE isn’t really making MOXIE bigger, that’s kind of straightforward. The two biggest challenges — the first one is we’ll need 25 to 30 kilowatts of power to do this. Now, that’s not a custom requirement for MOXIE. We’ll need 25 to 30 kilowatts of power to support a human base on Mars. So we have to do that anyway, but that’s a critical technology.

And the idea is that MOXIE goes first along with the power system, along with a habitat, along with an ascent vehicle, along with anything the astronauts will need. And because of the way the orbital mechanics work out, you get a chance to go to Mars every 26 months. It takes about six or seven months to get there. So you have over a year and a half once you’ve landed all this stuff before the astronauts take off.

And so, we would use that year and a half waiting for the takeoff to get everything ready, including making all this oxygen with this 25- or 30-kilowatt power system. And once the astronauts arrive, we turn the power system over to them. But that is a big tall pole. And then there’s the other end, learning how to store all that oxygen without it boiling off. To liquefy it and store it, that still needs to be developed as well. So I think the power and the refrigeration at the far end are the next big things to worry about.

Host: And then when we think about the hardware, what size is the hardware now, and what size do you think it will have to be to actually work in the way that you just described?

Hecht: Well, right now, what we’ve got is weighs about 18 kilograms. It’s the size of maybe a very small microwave, a large toaster as you’d prefer. What we anticipate needing is something that’s more a cubic meter. So the size of a small chest freezer, for example, and a washing machine, something like that, and will weigh about a ton.

And that would give us our two to three kilograms an hour. We do two to three kilograms an hour for 10 or 11 months, we’ll have our 25 to 30 tons of oxygen at the end. So that’s the scaling. And people are already working on scaling up parts of MOXIE to show that we can do that two to three kilograms an hour in a reasonably compact system. And it’s looking very promising.

Host: So, once it gets to chugging along, it just keeps going?

Hecht: Well, that’s a really good question, Deana. One of the biggest challenges we face now is that we get to run once a month or so. And each time we run, we have to heat this thing up from the Martian, from a cold temperatures up to 800 degrees centigrade, and then we turn it off and it cools down again.

And it turns out that’s one of the most damaging things you can do to this kind of technology. It really can’t survive too many of those thermal cycles. It’s much, much healthier and much safer to just turn it on and have it run. So, in that respect, the real thing is going to be far less challenging than MOXIE on Perseverance is because we’ll just turn it on and let it run continuously.

Host: Wow. Do you have any expectation right now as to what that lifetime will be for the device once you actually get it on Mars in an operational state?

Hecht: We will have to design it to, of course, make enough, make our 25 tons of oxygen. And that will be a combination of robustness, making sure it will run for that amount of time and a certain level of redundancy. So you allow for some failures. And once we’ve done that, we will need to run for at least a year. And you know how NASA works so that they’ll design it to make sure it runs for three years to make that work. And that’s about the right number. I mean, usually there is a factor of three or four placed on these things.

It remains to be seen how they will validate that short of actually running it for three years. That’s kind of a new sort of requirement. You’ll notice on some of these, on the Rovers with the famous one is looking at the MER, the Spirit and Opportunity expectation to run 90 days, and they ran more like 10 years. Well, that’s less about how it’s built and more about how it’s tested. So if we need this to run for a full year, the testing is a challenge, and that’s one of the reasons we’re trying it out on Mars now so that we can build confidence.

Host: What’s next for MOXIE?

Hecht: Well, we’ll just keep chugging along for the rest of the primary mission. We’re now on sols, about 200 days in. We call them sols on Mars. And the primary mission goes a Martian year. So that’s upwards of over 600 sols. So we’re maybe almost a third of the way through right now. And we’ll keep running and then through the different Martian seasons in a day and night, monitor how the performance might change over time, or might not, hopefully.

And also keep coming up with these kinds of clever experiments that tell us subtle things about the instrument that we can’t measure directly. And in addition, we’ll be working in the laboratory quite a bit, working very hard, doing experiments in the lab that you can’t do on Mars, simply because you just can’t get in there and tinker with the wires and the knobs on Mars, the way you can in a laboratory.

Host: And I’m sure you’ve spent a lot of time in the laboratory and in the development of MOXIE. Are there lessons learned that you could share that might be beneficial to NASA’s technical workforce?

Hecht: Oh, gosh. I almost wouldn’t know where to start with lessons learned. In fact, we can have a whole other, an hour-long discussion on that without losing steam. I’ll try to pull out a couple of things. First of all, I’ve worked, and of course, I worked for 30 years at JPL, and I’ve been on the end of leading instrument development projects.

I can’t give enough credit to the subcontractors, particularly a group that’s now called OxEon Energy. It was called Ceramatech at the time. There was some reshuffling, but that group developed this actual solid oxide electrolysis system. And there was another group, a company by the name of Air Squared that developed the compressor. And what they have in common is that neither one of them had ever done anything for flight before. So we really had a choice to make as program managers, as project managers. Do we take a company that’s experienced in space flight and space instruments and teach them how to make solid oxide electrolysis cells or compressors, or do we take companies that are really good in those technologies and teach them how to make a space instrument?

And that’s a fundamental decision. And we had some choices. And we went with the companies that were both good at those technologies, were large enough to really have the capability to pull this off. They knew what quality assurance is, for example, but were still small enough to be agile, to be nimble, and frankly, to be excited about this opportunity, even if it’s not necessarily good for their bottom line. And I can’t give both of these companies enough credit.

Air Squared for the compressor, and in particular, OxEon Energy for developing this electrolysis stack, we call it, and continuing to develop new products under NASA funding to lead us to a full-scale system. So that’s one lesson. Go with the people who know the technology. Teach them how to do things for space.

Another one, we’ve been looking at all the choices we made, and I have to put this carefully because I don’t mean it to be negative. All the choices we made during development that have made operation difficult, OK? The choices were made for good reason for the most part. Sometimes those good reasons though, are kind of a, I won’t say a flaw in the system. But to give you an example. So, the safest way to run MOXIE is to specify the voltage that we put on the electrolysis cells. Because it’s when the voltage gets too high, that you start making carbon. Our requirement, however, was to make a certain amount of oxygen. That was the requirement laid on the project, by agreement with NASA. ‘You’re going to make six grams per hour of oxygen.’ That requires having a constant current, not a constant voltage.

So, to meet the requirement, all the development was done with a feedback circuit that adjusted the voltage to make a constant current, even though safety demanded adjusting the current to make a constant voltage. And we’re only now doing the laboratory validation to allow us to run in constant voltage mode. So in a sense, there’s situations you get into where your requirements conflict with operations. I remember being taught that a long time ago — design your instrument for operations, and don’t design it for requirements. It’s a really interesting tension that project and program managers need to wrestle with.

And the only other lesson learned, I don’t know what the lesson is. I don’t know how it would have been done better. But we need to do much, much better in terms of monitoring controls, in terms of being able to measure what the system’s doing, to control what it’s doing. It’s very minimal. And it was minimal by design because emphasis was elsewhere. But again, when you’re doing operations, you pay for that minimalism. And that, I don’t call it a lesson learned, but that would be something that would bear some scrutiny and discussion if we were to do this again.

Host: Very good insight, Mike. Thank you for sharing that. Appreciate that.

Hecht: Of course.

Host: So, you’ve been involved with development of a lot of Mars science and technology instruments, as well as exciting discoveries over the years. What’s special about MOXIE?

Hecht: Well, they’re all special. I love all my children, right?

Host: (laughter)

Hecht: I can tell you what’s different about MOXIE. In the past the missions I’ve been this intimately involved in, and particularly the Phoenix mission back in 2008. They were small intimate missions. I mean, yes, half a billion dollars to most people doesn’t sound small, but it was a relatively small team co-located in one place. The rules were a little bit looser and more flexible. And it was if you will, a more intimate experience. But we had very focused goals and very, very restricted goals.

This mission for me, being involved in a mission the scale of Perseverance, where everywhere you look, there’s somebody working on something different and an instrument measuring something different, and you have to start, treat it like a corporation with many activities going on and balancing all those. That for me is a new and exciting experience. The other thing for me though, that is very new.

I mean, I’ve always considered myself a planetary scientist and here I am focused on enabling human exploration with an instrument that’s tucked inside the belly of a rover. And for purposes of MOXIE, we don’t care if the rover drives or doesn’t drive or if it’s on a mountaintop or in a valley. So in a sense, we’re isolated as an instrument from that whole scientific enterprise. And that’s new and different for me and learning to focus on the technology adventure and the future. And eventually seeing maybe your grandchildren and my grandchildren land on Mars, it’s exhilarating in its own way.

Host: That is perfect. It’s wonderful to hear about this mission. Mike, we really do appreciate you taking time to talk with us today.

Hecht: As I mentioned to you, Deana. I’m an old friend of APPEL and going way, way, way back. And I was just delighted to hear from you again and have an opportunity to contribute again.

Host: Well, we really do appreciate it. It’s great to be able to get connected again. Are there any things that we didn’t cover today that we might want to circle back to now?

Hecht: How many hours do you have?

Host: Well (laughter).

Hecht: Oh, let’s see. Well, again, thinking from the programmatic point of view, MOXIE was unusual in another way. It was co-sponsored and supported by three different NASA directorates. And those of us on the inside recognize how rare that is, that Space Technology and Human Exploration and the Science Mission Directorate all get together with a common goal and objective to build one thing and operate one thing.

And that’s worked very well by the way. But to me, it was truly notable that there was this convergence of interests and opportunities that came together. So, it exposed me to giving me an opportunity to make new friends. And I can’t ask for more than that.

Host: You’ll find links to topics discussed during our conversation at APPEL.NASA.gov/podcast along with Mike’s bio and a transcript of today’s show.

If there’s a topic you’d like for us to feature in a future episode, we’d love to hear from you. Connect with us on Twitter at NASA APPEL – that’s APP-el – and use the hashtag Small Steps, Giant Leaps.

As always, thanks for listening.