NASA EDGE: Biogeochemistry with Curiosity
The Mars Science Laboratory
- Jennifer Eigenbrode
BLAIR: We’re here with Jennifer Eigenbrode, who has one of the most unique and lengthy titles. You pretty much do a lot of everything. You’re Geo, Bio, Astro. What exactly is your title?
JENNIFER: I am an Organic Biogeochemist. What that means is I look at organic materials that may have been from biology or geological processes. It’s all chemical in nature so that’s why it’s Biogeochemistry. I do this type of investigations on Earth but now I’m also doing them on Mars.
BLAIR: Interestingly enough, you’re going to apply all these disciplines through the instruments on Curiosity, correct?
JENNIFER: Yeah. There’s a whole suite of instruments on Curiosity. This rover is packed full of a laboratory, basically it sits on its back. So, we can use this package of instruments to hunt for organic material in the Martian rocks at Gale Crater, which is where we’re going.
BLAIR: You picked that location because it was rich in some of these minerals that you’re investigating.
JENNIFER: Well, Gale Crater has layered rocks. Those layered rocks have recorded the environmental history of a very, very ancient Martian environment. What’s really intriguing about that location is that there are two minerals in particular that might have helped in preserving organic matter over the eons between when it was deposited and when Curiosity actually encounters those rocks. The first one is call nontronite. It is a clay mineral. This is actually a rather rare rock on Earth.
JENNIFER: But on Mars, we have been identifying this using CRISM data, which is an instrument on the Mars Reconnaissance Orbiter. This is the mineral that a lot of us are very, very interested in. Clay minerals are known on Earth to be very, very good at preserving organic materials. Over the course of eons, meaning billions of years, a lot of things can happen to a rock. And we need to be able to preserve the organic material in the rock in order to be able to discover it later. This mineral in particular might help us actually find it.
BLAIR: So you got an indication from MRO that it might be there or something like that would be there and you’re going to confirm that and look at it in detail with Curiosity.
JENNIFER: That’s correct.
BLAIR: Perfect, okay. Good.
JENNIFER: Now, the other mineral is a sulfate.
JENNIFER: This is salt, all right? This is actually rather common on Earth but sulfate minerals at Gale Crater make up that huge mountain that you see in the middle of the crater. Sulfate minerals precipitate out of water. So, these also have the capability of encapsulating organic material and then preserving it for a very long time. We have these two minerals that we think, based on everything we know now, might have helped preserve organic material if it was there in the first place.
BLAIR: Why do we want to find this organic material on Mars or why is it important from your geobio, astro background, why is it important that we find that there on Mars?
JENNIFER: What we really want to know about Mars is if the environment, the past environments were habitable. Meaning could they have supported life. One of the prerequisites for supporting life is the presence of organic material. That organic carbon is used by organisms as a source of organic for their biomass. All the cells have organic carbon that make up all little organelles, the cell membrane, all of that requires some organic material. Organisms can take in that organic material and incorporate it into their biomass. They can also use it for energy, and, in fact, they might even produce it and leave it behind if it was biological in nature. Organic material is probably part of a chemical system of Mars planet, just like it is on Earth but obviously, the history that Mars took is very different from the history that Earth took. And we don’t understand what that system really is. Now, the organic matter that we find, depending on what minerals we find it in, its association with different chemicals, the actual chemistry of the organic material itself, all of that information could tell us about the sources and the processes that have acted upon that organic matter over time.
JENNIFER: More clues as to what was going on in this environment. The Mars’ Science Laboratory mission is not going after the life question. We are going after was the environment habitable. But in the larger scheme of things, the astrobiology community and pretty much the public wants to know did Mars ever have life? It’s a big question and we have to put together this big puzzle in order to even approach it.
BLAIR: It’s harder because you, as a geologist can go out into the fields and pick up rocks and study them here on Earth. Much more limited and narrow opportunities as you look at other planets. This is your opportunity to go out and walk around Mars, if you will, and take a look at the rocks.
JENNIFER: That’s right. In the past, we’ve sent the Viking Lander. It just landed on top of regolith, one place, didn’t get to go anywhere and looked at the regolith, which is like the surface soil. This is soil that has been shifting around on the surface of Mars for a long, long time. It learned some things but it was limited in what it could do because sending a spacecraft to another planet is not an easy thing.
BLAIR: It’s very difficult.
JENNIFER: Then, we sent the rovers, Spirit and Opportunity and the whole history of rovers before that. What we found out, Mars has layered rocks. We didn’t know that before.
BLAIR: Isn’t that cool? Now you know.
JENNIFER: Mars has water. It still has water. It’s still moving around. Things are still happening on Mars. We didn’t know that before. We had all this stuff and now we’re going with this rover. It’s like sending a geologist, except that they have this whole backpack. Imagine that, having this enormous backpack with an entire laboratory and all sorts of really cool tools and they actually can move around, go from one place to another to another; look at this rock; look at that rock; investigate; drill; take a sample, study it. Look at the next one, drill, take a sample, study it. It’s unprecedented how much this rover is capable of doing compared to previous missions.
BLAIR: I’m just trying to figure out whether you’re excited about this or not.[Laughing]