EPISODE 105: SAMPLES FROM MARS

Transcript

Lindsay Hays: One of the things that’s really important about bringing samples back from Mars is that there are things that you can learn from return samples, things you can only learn by bringing them back to Earth.

What we’re going to be able to do is really investigate these samples to their full potential and really answer questions about Mars, the potential for biosignatures, its potential habitability, things like its historical record and age dating and things like that that we really have been not capable of doing before.

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.

Mars Sample Return is one of the most ambitious campaigns ever attempted. NASA and the European Space Agency plan to bring the first samples of Mars material safely to Earth for detailed study.

In October 2022 our podcast featured a Mars Sample Return overview, and you can check out Episode 94 if you want more background on the mission. One of the guests on that episode, Mars Sample Return Deputy Lead Scientist Lindsay Hays, is with us again to go into more depth about the science of the mission and specifically the samples from Mars.

Lindsay, welcome back to the podcast. Thank you for joining us.

Hays: Thank you, Deana. It’s so good to be back.

Host: What’s the latest on Mars Sample Return?

Hays: Ah, well, there’s some exciting stuff that is happening, and I’m excited to be here to share this with you all. Since the last time we talked, we have an initial cache. We have a whole set of samples that the Mars 2020 Rover put on the surface of Mars. We’re calling it the initial cache. It’s in the Three Forks region.

So we deposited a suite of samples, and I think the last time we talked, we talked about how up to the point where we deposited the cache, we were doing what we called paired sampling. So anytime we found a sample that we found, or a rock that we found particularly interesting that we wanted to take a rock core of, we collected two. Right next to each other or pretty close to each other, we would collect one sample and we would close the sample tube, store it on board, and start right again on a second sample.

So, of those sets of samples that we collected, we’ve put half of those paired samples, so seven rock cores, one of the two pairs of regolith samples that we collected, so Martian surface material — we don’t say soil for Mars, but we say regolith — and one atmospheric sample and one of the witness tubes. So, we have 10 tubes that are sitting on the surface of Mars and that are ready to be picked up as part of Mars Sample Return.

But the neat thing is, is that’s our sample cache that’s there to really buy down the risk. We have a whole second set of samples that the rover, that Perseverance is still keeping on board. This is the other half of those paired samples. So, we have those seven samples plus a new sample. We have one of the regolith samples, we have two witness tubes that are still on the rover, and the rover is off and exploring up the delta in Jezero.

With regard to Mars Sample Return, we’re coming up to the Key Decision Point this summer here for moving from Phase B to Phase C, and lots of pieces are coming together and we’re really excited about seeing all of this come together.

Host: We want to spend a lot of time today talking about Mars Sample Return, but just to give us a little bit of a basis to get started from, could you talk about samples in general terms and requirements for obtaining and returning samples from space to Earth?

Hays: Sure. So, what we’re learning about Mars Sample Return is that although there are some similarities between the different sample return missions that we’ve had, which is great, because we’ve got lessons learned, we’ve got the ability to understand what has worked and how to think about things and all of that. Each of these missions have different requirements, and each of these missions have been really, really different.

So, if you think for example about the samples that the humans returned from the Moon during the Apollo Era, we’ve just reopened some of those samples. That’s been a really exciting thing to see how samples that were curated for a really long period of time can be opened and available for new scientific techniques and new scientific examinations and experimentation that we never would’ve even imagined was possible when those samples were first collected. So that’s a really important thing that we understand, this thinking about long-term curation.

But when you think about something like OSIRIS-REx, where the samples will be coming back this fall, we’re all looking very excitedly to see how that mission is working. We’ve got some lessons learned from that as well about how to have a sample team and thinking about a facility and all that kind of stuff, but all of these missions are very different for different reasons.

Things like planetary protection, right? It’s very different if you’re thinking about planetary protection categorization to think about bringing samples back from an asteroid than it is to bring samples back from a place like Mars, which is a different categorization. We have different concerns about these things when we bring these samples back.

Another big difference is the amount of sample, right? We look at the amount of sample that was brought back with OSIRIS-REx, and they excitedly got much more sample than they expected, than they’d even hoped for, I think, but it’s still a different amount of sample than we’re really thinking about with Mars Sample Return. Compare that to the amount of sample we brought back from the Moon, which I think any sample scientist is just so excited thinking about the amount of material that came back from the Moon.

Additionally, things like the context information, right? The way we put these samples in context of the environment that they were found in and all of that kind of stuff, all of that’s different for these different kind of missions. Again, and I think that one of the things that we can see that’s really consistent across this is the importance of curation and long-term preservation.

So, we’ve done some sample return missions, and some of those happened quite a long time ago. Some of those are really coming to fruition right now. But there’s some lessons learned, but they’re all really different at this point, and so there’s a little bit of newness for each of these missions.

Host: Why is it important to get samples from Mars?

Hays: So, one of the things that’s really important about bringing samples back from Mars is that there are things that you can learn from return samples, things you can only learn by bringing them back to Earth. There’s a couple reasons for this, but the two that we think of as the most important reason, on one hand is that there’s instrument limitations, right? When you send a spacecraft to Mars, one of the things that you have to do is you have to pick the instruments that you want to put on board.

Now, we’ve been able to send some fantastic instruments to Mars, and we’ve been able to do some really interesting studies and learn a lot. The Mars 2020 Rover is an incredibly capable rover. But there’s always going to be limitations for power and size and other things like that that you’re going to have to think about bringing your travel-sized version of some of these different things.

So, there’s some things that when you bring those samples back to Earth, certain investigations, you can do it with a synchrotron or something like that that is literally a building-size instrument. These are things you can’t imagine sticking onto a rover and bringing with you.

Alternatively, you have to think of science as a sort of iterative process. So you do an experiment on a sample and you learn something particularly interesting, and you realize that maybe you need to think about a different kind of experiment to understand what you saw there.

Now, when you have a rover, even if it’s a very capable rover, there’s some instrument folks that can do some really interesting things and use instruments in ways that we didn’t necessarily envision when we first selected them. But fundamentally, you’re somewhat limited in that sort of iterative investigative process.

So by bringing these Mars samples back to Earth, what we’re going to be able to do is really investigate these samples to their full potential and really answer questions about Mars, the potential for biosignatures, its potential habitability, things like its historical record and age dating and things like that that we really have been not capable of doing before with the samples, even with the most capable rovers that we had.

Host: How does the Mars Sample Return mission impact human missions to Mars?

Hays: Oh, that’s another one of the really exciting aspects of the Mars Sample Return mission, is that there’s a lot of things that we’re doing with Mars Sample Return that have sort of these long tails of importance, right? So some of these are engineering, right? We are demonstrating capabilities to accomplish roundtrip missions. We’re showing that we can land heavier and heavier spacecraft on the Martian surface. We’re advancing this terrain relative navigation, this precision landing technology.

If you recall, the Sample Retrieval Lander is going to have to land relatively close to where Mars 2020 is because that’s the primary way we’re thinking about those samples being delivered to the MAV and the OS, the orbiting sample container within the Mars Ascent Vehicle. So, you need to get it relatively close, and to do that you have to get increasingly good at precision landing technology.

We’re going to launch a rocket from another planet for the first time, we’re going to do autonomous in-orbit rendezvous around another planet. All of these things are particularly exciting stuff. But then in terms of the science and the information that we can learn to really buy down risk for humans themselves, things like assessing rock and dust characteristics, there’s potential hazards there.

When we went to the Moon, these are things that we had to sort of guess at, and we learned a lot from operating on the surface of the Moon. But the cool thing about Mars Sample Return is it’ll help us answer some of those questions early. Things like how abrasive is the dust, right? This wound up being a really big issue with the Apollo astronauts, and it’s something that we have the potential to understand more about in advance of humans to Mars. Things like radiation absorption of the regolith, how good the regolith may be in forming protective environments.

Additionally, things like survivability of seals and our ability to understand how things that sit on the Martian surface for a long period of time are affected by the conditions, the thermal cycling, the dust, that sort of thing. So, there’s a lot of things that we’re hoping to learn from the Mars Sample Return campaign that’ll really inform us better about human missions to Mars.

Host: What’s unique about how and where you’re getting samples for the Mars Sample Return mission?

Hays: So, I’m actually going to answer that question in reverse and say one of the cool things about where we’re collecting these samples from our sample return is that one of the major goals for this mission was to get both igneous and sedimentary rocks, so that we can look at things like biosignatures and be able to do some age dating kind of things.

One of the really cool features about the Jezero Crater is that because as best we could tell from geomorphology and the shape and looking at some of the minerals that we could determine from orbit, it was an ancient delta into a crater lake. Now, one of the things that we know about deltas on our planet is that they’re good places for sedimentation and preservation.

So the hope was that it would be a really great place for us to, if there are biosignatures or organic material of some type that was derived from Martian environments, that it would be a good place for those organic biosignatures or other biosignatures to have been made by organisms in that area if there were any organisms, preserved because of the high rates of sedimentation that happened when you have a river bringing a lot of sediment and then depositing that onto the delta. Then easier to detect, because by nature of the fact that this delta has now been eroded, some of the fantastic pictures that you can see from the Perseverance Rover, you’re seeing these fantastic delta faces. We’re seeing all these great bed forms and all of this great geology that’s really helping us to put this in context.

So, the where was really important, because you’ve got to go to a place where you think you’ll be able to find the signal that you’ll be able to see. We were really, really lucky to be able to see some igneous rocks early in the mission as well, so we were able to collect some of these rocks that we hope will be really important for dating again, and so this will be really great.

But the how is actually even cooler in some ways, because this mission was designed, and I’ve said this a couple times, and I love thinking of the Perseverance Rover as a fantastically capable, scientifically capable rover, right? It’s got fantastic instrumentation for understanding the environment that it’s in, and that fantastic scientific instrumentation is allowing us to not only collect these samples, but also understand the context.

So, it’s one thing to be able to say, here’s a rock. In this rock we found this mineral or this compound, or whatever. It’s entirely more to be able to say, that’s not only interesting in and of itself, but it’s interesting because we see it in this layer, in this rock, and we can tell by the other layers nearby that it’s older or younger than this other feature, or that it was cross-cut, which means it’s younger, but in a particular way than this other feature.

It allows us to not only say, here’s what this thing means, but here’s what this thing means in the context of Jezero Crater and in the context of this region on Mars. Even better, here’s what this means in the context of the whole history of Mars as a planet. So, this mission, the Perseverance Rover, and then the follow-up missions for Mars Sample Return are really allowing us to get this fantastic context history of this really interesting place.

Host: As a scientist, what are the precautionary measures that you take for planetary protection in a sample return mission?

Hays: Oh, this is something that we are taking extremely seriously for a sample return, and particularly for Mars Sample Return, right? We think of a couple different things that we’re doing. One is containment, right? We’re thinking about multiple layers of containment for these samples. So the core samples and the regolith samples and the atmospheric samples, all of these things, they’re all sealed in the sample tubes.

Then the sample tubes go into the orbiting sample container, and then that’s going to go into more layers of containment. So multiple layers of containment, but we’re thinking about having these seals be very strong and be very complete and that sort of thing, and then we’re also thinking about breaking the chain.

So once you have these samples in multiple layers of containment, then you think about sterilization and what are some ways that you can create a sterile environment on the outside of a seal that you have the non-sterilized environment inside of. So, there’s different ways that we’re thinking about that right now, but there’s a combination of containment and sterilization that we’re working on and we’re testing for this mission.

Then also, once the samples come back to Earth, part of the reason that we’re thinking about building this high containment facility, the Sample Receiving Facility, is that we need to be able to be sure that we can do what we’re thinking of as a sample safety assessment. So, we get all these samples back to Earth, and then we test them for various things to understand what’s there, what we can understand about potential biological hazards, other potential hazards, and all of that sort of thing before the samples get released. We’re going to have this assessment that will happen and make sure that the samples are safe for release.

Host: How delicate is the packaging process?

Hays: Oh, so both literally and figuratively, there’s multiple layers to this packaging process, right? So in preparation for the Mars 2020 mission, there’s lots of testing that went into how you drill samples, how samples get put into the sample tube, how to seal these sample tubes, what are the best ways that the seals can work, and how is that affected by conditions on the rover and conditions that these sample tubes may see on the surface, and all that kind of stuff.

So the sample tubes themselves, there was a lot of work that went into designing those, because all of those had to be loaded on the 2020 rover and sent off earlier than the rest of the mission. So, that all is in place and that’s all set. But now for the Mars Sample Return campaign in these later missions, we’re paying attention to things like sample integrity, right? Things like what happens within the sample tubes if they get heated? What happens within the sample tubes if they’re exposed to magnetic fields? What happens to the samples in the tubes if there’s certain types of shaking or things like that?

So, the first part was sort of in thinking about encapsulation. Then there’s thinking about sample integrity. But then for the Sample Receiving Project, this facility and things like that, we’re thinking about the final stage, how to open the samples. First, how we can get the headspace gas. So, within each of the sample tubes, there’s either a piece of rock or a couple pieces of rock, and then there’s some gas that was basically Martian atmosphere that was collected at the same time.

So how do we get those little bits of Martian atmosphere out, because that’s its own kind of sample as well, and something that there’s certain scientists who are very interested in what we’ll be able to learn from those little pieces of the atmosphere.

So first you want to extract all that gas, then you want to think about how to open the tubes with minimal effect to the samples themselves, the rocks or the regolith inside. Then if possible, if we can do it, we’d love to be able to make sure that when we take these samples out, we maintain whatever layering or levels, the relationships between the levels in the rock that we can see.

So, there’s a lot of different steps about the packaging process and the unpackaging process, as well as thinking about how we can minimally affect the samples themselves.

Host: Then what happens once the samples get back to Earth?

Hays: Oh, and then the real fun begins. No, it’s all fun. There’s all kinds of interesting things. Once the samples get back to Earth, it’s opening the sample tubes, it’s getting the gas out, it’s getting the rock samples out. It’s thinking about basic characterization, like how much does this rock weight? And things like what are the minerals that we can see here? And how many pieces is it split into, and how many surfaces are there? There’s things like preliminary examination where we’ll try and figure out other features of the rock itself and the material that’s there.

These are things that are mostly curation and understanding ‘just what do we have here?’ Then there’s also some basic science that we want to start doing. We think about a couple different types of science. We think about time-sensitive science. As soon as you open the tubes, the samples start re-equilibrating with the environment around them, so there’s some things, water loss and other volatile loss that you want to try and make some of those measurements early.

One of the things we’re thinking about is a sample safety assessment. I mentioned this before. The idea is how can we tell that there’s nothing on these samples that could be harmful or that we can really understand what’s on these samples? Because if we need to take samples out of containment and we can’t absolutely verify a sample safety assessment, there’s always the option to sterilize the samples before they’re released from containment.

That’s great, that’s fine, absolutely fine for certain types of science. There’s no problem for certain scientific measurements, experiments, working those on samples that have been sterilized. Other scientific measurements, you will potentially lose some information when they’re sterilized. So, either we want to understand the samples are safe before they’re being released, or we may want to do some of those sterilization-sensitive measurements within the Sample Receiving Facility. So there’s a lot of early science — we have some science objectives.

Then just like those other sample retrieval missions that we’ve talked about in the past, OSIRIS-REx and the Apollo samples, we’re going to want to think about some portion of these samples going for long-term curation, right? Some portion of these samples are for the world and the future, and future scientists who may not even be born yet, may come up with new and interesting techniques for making some of these measurements. So we want to think not only about the immediate science objectives we want to do now, but also saving some of that for the future.

Host: Will you get to be involved in this?

Hays: Oh, well, I’ve been involved for a while, right? I mean, all of this is part of the job of a program scientist and thinking about this science, but I will not probably be one of the scientists in bunny suits performing experiments and making measurements and the like, but I certainly hope to be able to visit these samples, these samples that we’ve been thinking about for a long, long time to see how the facility works, and to actually set my own eyes on some of these samples.

Host: Lindsay, I’ve got to ask you, is working on Mars Sample Return a dream come true for you?

Hays: ‘Yes’ is the short answer.

Host: Short answer.

Hays: The long answer is there are rarely opportunities to be able to examine materials from far away, from things like meteorites and things that have come from the surface of a different planet, of a whole other world, whether or not it’s Mars, whether or not it’s the Moon, whether or not it’s a sample of an asteroid or something like that.

Being able to examine these things and to think about these materials that were created in an entirely different environment under the same laws of science and chemistry and those sorts of things, but just an entirely different environment and the ability to think about all of the things we could learn, not just about Mars, but also thinking about what it can tell us about the Earth and things like that. I think that there’s so much potential, right? These samples, in some ways they’re just pure potential, and that’s just so exciting.

Host: Well, it’s always a pleasure getting to talk with you. Thank you so much for being on the podcast today.

Hays: It’s been great. I really appreciate you having me back and the ability to talk about Mars Sample Return.

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

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