Trying To Find Life On Mars? Start In The Australian Outback.

12:15 minutes

an artists rendering of a rover on mars
The Mars 2020 rover. Credit: NASA/JPL-Caltech

NASA’s Mars 2020 mission is just around the corner. Next fall, the Mars rover will launch with an upgraded suite of instruments to study the red planet in a way Curiosity and Opportunity never could. When it lands on Mars, it will search for and try to identify signs of ancient life. But how will it know what to look for?

flat-ish speckled rocks next to and in a shallow lake
Stromatolites at Lake Thetis, Western Australia. Credit: Ruth Ellison, via Wikimedia Commons/CC BY 2.0

One sign of Martian life could look pretty familiar: ancient stromatolites, layered rocks built by microbes that were one of the earliest lifeforms on Earth and were abundant 3.5 billion years ago. Stromatolite fossils are now only found today in a few areas of the world, like the remote outback of Western Australia. That’s where NASA scientists are headed this week to study them, hoping to gather clues about whether this organism could have also lived on ancient Mars. 

Scientists on the Mars 2020 mission Katie Stack Morgan and Mitch Schulte talk to Ira about the chances of finding evidence for ancient life on Mars.

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Segment Guests

Katie Stack Morgan

Katie Stack Morgan is a deputy project scientist for Mars 2020 at NASA’s Jet Propulsion Laboratory in Pasadena, California. 

Mitch Schulte

Mitch Schulte is a Mars 2020 program scientist at NASA and is based in Washington, D.C.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow. Later in the hour, we’ll be discussing how land and soil can be used to both hurt or help the environment. But first, NASA’s Mars 2020 mission is now just around the corner. Next fall, the next Mars Rover is scheduled to launch with an upgraded suite of instruments to study the red planet in a way that curiosity and opportunity never could.

Now one of its main objectives when it gets to the Martian surface will be to search for and identify signs of ancient life on the red planet. But how will it know what to look for? Well, one sign of Martian life could look pretty familiar– evidence of ancient stromatolites. Those are one of the earliest lifeforms ever discovered on Earth. Stromatolite fossils are found today only in a few areas around the world, including the remote outback of Western Australia.

That’s where NASA scientists headed this week to study them, hoping to gather clues about whether this organism could have also lived on ancient Mars. Here to tell us more about what they’re looking for this week, coming to you all the way from Pilbara region of Australia is my guest Mike Schulte, Mars 2020 program scientist. Welcome to Science Friday.

MITCH SCHULTE: Good morning.

IRA FLATOW: Good morning to you. Thank you for joining us. Also joining me from JPL headquarters in Pasadena, California is Katie Stack Morgan, deputy project scientist for the Mars 2020 mission. Welcome, Katie.


IRA FLATOW: Mitch, let me ask you first. You’re with a group of NASA and European scientists down in Australia, right? Why is Australia such a great place to go looking for them?

MITCH SCHULTE: So Australia is a great place to look for these because it contains in the rock record some of the most ancient evidence for life on Earth. These rocks here in Western Australia are 3 and 1/2 billion years old. And they contain these stromatolites, these micro fossils that we see in the rock record. And this is one of the very few places in the world that has this old rock record that contains these traces of ancient life.

IRA FLATOW: So are you sort of like taking photos of them, so that when the Rover sends back a photo, you might be able to compare them, for example?

MITCH SCHULTE: Well, so mythology is only one clue that we use to determine whether something is evidence of life on a rock record. In this particular case, one of the big clues, though, is how they visually look. A lot of times, people see these in two dimensions, and they’re not convinced by the biogenicity any of these things. And so really getting out into the field to see them in three dimensions to study the rocks and what the rocks tell us about the environments is also very key to really helping us decide that these are evidence of life.

IRA FLATOW: So what are the conditions on Mars in which a Martian stromatolite would have grown? Same as Earth?

MITCH SCHULTE: Well, we think so. There are a variety of environments here on Earth where we see stromatolites forming today and where we see in the rock record, again, the environments being told from the story of the rocks. And so we think that similar kinds of conditions would have existed on Mars. So for example, we see stromatolites forming today in hot spring environments. And we see evidence on the surface of Mars that there may have been hot springs in its ancient past.

We also see a lot of stromatolites forming in lacustrine, our very shallow marine kinds of environments. And we interpret those from the rock record for these ancient rocks, and we think, especially where Mars 2020 is going to land, that there was an ancient lake environment where the Rover will be landing.

IRA FLATOW: That is cool. Katie, the 2020 Mars 2020 mission is designed also to look for a few different signatures of life, not just stromatolites, right?

KATIE STACK MORGAN: That’s right. So Mars 2020 is headed to a place called Jezero Crater. It’s an ancient crater on Mars. And what’s really exciting about the comparison between the rocks in Jezero and the rocks in Australia is that we’re talking about rocks of about the same age or even older on Mars. And so the kind of life that we’re seeing in the rocks preserved in Australia may very well be similar to the type of sign of life that we could expect to find in Jezero Crater on Mars with 2020.

IRA FLATOW: Well, let’s talk about– we’ve had rovers on Mars for a long, long time now. How is this mission different from all the other rovers, Katie?

KATIE STACK MORGAN: Yeah, so Mitch talked a little bit about how the shape of the rocks and the shape of the stromatolites is only one way you can identify a potential biosignature. The Mars 2020 Rover has, as part of its instrument payload, a series of instruments that can not only take images of the rocks, but also map out their composition and whether they have organics in them.

And that’s really exciting in terms of building a case for a biosignature. It’s not just what you see, but also what the rocks are made of and whether they have organics.

IRA FLATOW: OK, let’s say you find stromatolites. Any way to get them back to Earth? You’ve now found some valuable information, right?

KATIE STACK MORGAN: Yep, well, Mars 2020 is the first mission in a potential series of missions whose objectives is to bring Mars samples back to Earth. And so our job with Mars 2020 is to find the best possible samples we can in Jezero Crater and cache them and collect them on the surface for a possible future mission to go pick them up.

IRA FLATOW: And so are you saying that you can positively identify a stromatolites with the equipment that you have on the Rover?

KATIE STACK MORGAN: We can make a really good case for one. But we’re not going to be able to positively identify the signs of life likely until we get those samples home if we get them home.

IRA FLATOW: Yeah. Mitch, how are you going to know how old the Martian stromatolite fossils are if you find them?

MITCH SCHULTE: Well, there are a variety of ways of doing that. One of the things that we see here in Australia is that there are different kinds of rocks in which these microfossils are encased. And there are minerals in those that can be radiometrically dated. The other way that we can do that is look at layers above and below where the microfossils exist, and we can often date those kinds of minerals as well.

So on Mars, what we’ll try to do is collect some rocks that contain these kinds of minerals that we can radiometrically date so we can actually try and pin down the dates of those microfossils if they exist.

IRA FLATOW: All right, Katie, what about the recent detection of methane on Mars? Does that make you feel like you might find stromatolites or any forms of other kinds of former life?

KATIE STACK MORGAN: Well, the methane detection by the Curiosity Rover in Gale Crater is very exciting from an astrobiological perspective. We don’t quite know exactly why we’re seeing that signal on the timescales that we are in Gale, but I think it does increase our excitement about the chances of finding life, and for us on Mars 2020, ancient life on the surface of Mars.

IRA FLATOW: Is it basically thought amongst scientists, geologists who now work on Mars that it’s a given there might have been life on Mars one time or another, given that all the water and the evidence of water there has been, Mitch?

MITCH SCHULTE: Yeah, so that’s really one of the reasons that we are excited about Mars, is because we do see this evidence on Mars’ surface that there was water in Mars’ past. And knowing that Mars and Earth are sort of similar geologically, some of the kinds of environments that we think existed on Mars long ago are the kinds of environments that we see this evidence preserved here on Earth. So it is very exciting, and the possibility we think is there that life could have started on Mars as well.

IRA FLATOW: How far is this Rover going to rove around? How many days? What is the length? Is this a three hour tour? I mean, what are we talking about here?

MITCH SCHULTE: So the prime mission is currently for one Mars year, which is about two Earth years. So and that has the capability to traverse about 20 kilometers. We’ve seen from our previous rovers that they’re capable of doing better than that, but that the mission design is for 20 kilometers, so that gives us a lot of range to be able to do that. And having the mission be for one Mars year gives us a lot of time.

IRA FLATOW: And are you putting the Rover down in a spot that you think is most likely to find evidence of life?

MITCH SCHULTE: Yeah, that’s the idea. And so selecting the landing site was a process that involved the entire science community. So we had a series of workshops to define what would be the best place to send the Rover. And so through this series of workshops and then making the decision at NASA headquarters, we’ve chosen Jezero Crater, partly because we see evidence of a river coming into what was once a lake that filled this crater that Katie talked about. And so we see various types of minerals in from orbital data that also indicate that there were environments that would’ve been conducive to hosting life at least.

IRA FLATOW: How did it go out on the field there, Mitch, this week in Australia?

MITCH SCHULTE: It was really great. So as you mentioned, we had both the Mars 2020 and the ExoMars 2020 Rover teams here. And there was a lot of great collaboration and great cross talk. And I think it really opened people’s eyes to see these rocks firsthand, because you read about these. If you’re a geologist like I am, this is one of those bucket list places you have to go to see some of the oldest evidence of life on Earth. And I think the scientists were really excited to come here and see these rocks for themselves. So it’s been a really great week.

IRA FLATOW: Do you have a bunch– Katie, is there a cavalcade of instruments on board this Rover? I mean, what kinds of instruments will it have?

KATIE STACK MORGAN: Yes, there are. We have a bunch of new instruments and some updated instruments from the Curiosity Rover. So we have improved cameras. We have some geochemistry instruments, as well as the mapping instruments I talked about. We also have the ability to see into the subsurface with our radar instrument. And we have a technology demonstration to produce oxygen from CO2 in the Martian atmosphere.

IRA FLATOW: All right, let me back that up again. You’re going to make oxygen out of the CO2?


IRA FLATOW: And is that a demonstration of possibly inhabitation and making your own oxygen?

KATIE STACK MORGAN: Well, it’s a technology demonstration thinking about the future of humans to Mars, so preparing for that. So of course, if we were to send humans to Mars, we would need oxygen both to breathe, but also particularly for the fuel to get those astronauts home. And so we’re demonstrating that technology on the surface of Mars with this mission and are excited to see us do that on the surface of Mars.

IRA FLATOW: What kind of fuel would you make out of the CO2?

KATIE STACK MORGAN: So it would be oxygen, oxygen based fuel.

IRA FLATOW: Such as hydrazine or something? I’m just guessing.

KATIE STACK MORGAN: I’m not– I think that’s a pretty good guess.

IRA FLATOW: [LAUGHS] Mitch, do you have any thoughts about that?

MITCH SCHULTE: Yeah, so the oxygen, of course, in order to burn things, you need an oxidant. And so oxygen is a really powerful oxidant. So we would combine the oxygen with some other fuel source, such as– and so for the rockets that go to Mars, they typically burn either hot liquid hydrogen or kerosene. That’s the reduced form of the fuel. And then you need an oxidant to burn it. So in order to get the people off the surface, you’d have to have some reduced form of fuel, but making the oxygen would be a really great step to be able to get them off the ground.

IRA FLATOW: All right. We’re going to watch this very closely, and thank you for giving us a heads up on this mission. Mitch Schulte, Mars 2020 program scientist with NASA. Katie Stack Morgan, deputy project scientist for the Mars 2020 mission. Thank you, both, for taking time to be with us today.

We’re going to take a break. When we come back–


IRA FLATOW: You’re welcome. We’re going to talk about using land in making a climate change maybe from worse to better. There’s a way to turn around climate change using the soil. We’re going to talk about it after this break. Stay with us.

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