Isidis, Martian Impact Basin
Interview with Colin Pillinger
On Christmas day, the European Space Agency's (ESA's) Beagle 2 lander is believed to have touched down on the surface of Mars, in a region known as Isidis Planitia. Beagle 2 contained a suite of scientific instruments designed to search directly for evidence of life on Mars. Although scientists expected to receive a signal from the lander shortly after touchdown, they have not yet detected one. They remain hopeful, however; there will be more opportunities to communicate with the spacecraft in the coming week. Earlier this month, Astrobiology Magazine spoke with Professor Colin Pillinger (Open University, Milton Keynes, UK), who heads the group that conceived and developed Beagle 2, and that is responsible for its scientific mission.
Astrobiology Magazine (AM): Can you start by describing the goal of the Beagle 2 experiments?
Colin Pillinger (CP): Very briefly, it's to see whether there was, is or could be life on Mars.
|Mars Beagle 2 spacecraft.
AM: And is the Gas Analysis Package experiment the main experiment that you plan to do to determine that?
CP: Yeah, but we see this as a total package. I don't want to find myself in a position of having information which I can't interpret in context. We want to understand the chemistry of rocks, the mineralogy of rocks. We'll look at them with our microscopes and we'll see the environment in which we find them with our panoramic cameras. We will then analyze them using the Gas Analysis Package to see whether there are minerals deposited from water, whether there is organic matter which could be the relict material of organisms that lived in the water, and so on.
We're going to try to take samples from inside rocks so that they are much more pristine material than you find on the outsides of rocks, and we're looking for soils beneath the surface, particularly one which is likely to have been protected by a large rock. So it's the whole package. We like to think of this as a holistic experiment. It's a complete laboratory.
|The robotic arm of the Viking 2 Lander extends to collect a sample of soil for analysis. Click to enlarge.
AM: Beagle 2 will conduct the first biology tests on Mars since NASA's sent its two Viking landers there in 1976. Viking's results were very controversial. How will the design of Beagle 2's experiments help you avoid similar ambiguities?
CP: Viking did a very noble job. They had three experiments, which were configured to see whether there were any actively metabolizing organisms on the planet. When they got results which could be interpreted as actively metabolizing organisms, they got very concerned, because they had an experiment onboard called the Gas Chromatograph (GCMS), which couldn't detect any organic matter. So their interpretation was that the chemistry of [the martian surface] was playing them a big confidence trick and giving them that they impression that they had found biology, when in fact they didn't.
I'm not doing a metabolism experiment. The thing which is crucial as far as I'm concerned is we need to see whether we can detect any organic [biologically produced] matter. We know that there is organic matter in martian meteorites. My impression is that it's more than should be there, more than can be accounted for by contamination. Now I want to go back to Mars and see whether or not there's organic matter in martian rocks on the surface, where I can discount the contamination problem because these rocks haven't been to Earth.
And the way in which I plan to detect organic matter is to burn it. One of the failings of the GCMS experiment could be - and I'm not saying it is, I'm saying could be - that if there was any organic matter there, it was sufficiently chewed up - almost converted to graphite, or elemental carbon - that it would not break down [in the GCMS experiment] to give you a signal. However, any form of carbon will burn to release its carbon into carbon dioxide.
If you burn a sample of rock, or heat it up, you should see any organic matter burning to give you CO2, and at a higher temperature, you should see mineralogical carbonates breaking down to give you CO2 as well. You can separate these two things according to the temperature regime at which [they burn].
If you find the two carbon-containing phases, the inorganic (carbonates) and the organic, together, you have to measure the isotopic fractionation between them. I'm looking for carbonate as evidence that water was there. And also to give me a handle on the isotopic composition of the martian atmosphere, the basic material with which any biology might be working. On Earth, the organic material that co-exists with the carbonate is always enriched in carbon-12, due to biology, relative to the carbonate. This has been borne out on 10,000 samples on Earth. People have spent their lives working on this stuff, analyzing every sedimentary sample that they can lay their hands on. And it's always true.
AM: Isn't there still a possibility, though, that you could get a false positive or a false negative?
CP: Well, part of the reason that I want to do things in a way in which I have all the information to hand is that when I get something I want to be confident that the results I get are in context. I hate snapshots, or one piece of the jigsaw. So we'll do all the experiments that we said and we'll try and put the whole thing together and say, does this thing fit in a holistic way?
This is almost what went wrong with Viking: they took snapshots of things when they didn't have the other information. And then they were forced - as quite rightly they should have done - into saying, well look guys, we could have been being fooled here. And they did absolutely the right thing and said, there's another interpretation you could put on these results, and in fact we think the other interpretation is more logical than saying we found life on Mars was. They were very, very excellent scientists that made this interpretation.
Everybody can always find something confusing that they haven't thought of. But we have to do the experiments and look at the results, not go in there with closed eyes and say, this result must mean this. You have to look at everything, at all the information you get.
AM: Can you talk a little bit about the factors that went into choosing Isidis Planitia as the landing site?
CP: Everything we could possibly think of went into choosing Isidis. We wanted somewhere we could keep the scientists happy and somewhere the engineers wouldn't throw a wobbly. The engineers want low altitude, which makes the parachute work better; they don't want the place strewn with rocks, it could burst the gas bags; they don't want slopes because they give you lateral velocity that you don't like; nobody wanted to go to high latitudes, because it gets cold up there; we chose the northern hemisphere because it was going toward spring and summer, and of course the altitude there as well.
|Landing ellipses centered on Mars' third largest impact basis Credit: NASA JPL/MSSS/MOC
We liked a place where there was a potential of different kinds of rocks. So Isidis is nice because it's an in-fill basin, which might have lots of materials from the southern highlands washed down into it. We chose a place south of two recognizable sizable craters because we felt there was a possibility that some materials had been ejected from the floor of the craters.
AM: Beagle 2 was developed and deployed on a shoestring budget. There are some people in the scientific community who thought it was never going to get launched.
CP: Some of our people thought it was never going to get launched, let's put it that way. The more they thought that, the more we were determined it would. So thank you very much for those stimulating comments, all you people out there who thought it wasn't going to get launched.
AM: Can you talk a bit about your approach and your philosophy. How did you manage to pull it off?
CP: You don't have any money, you think harder. That sums it up.
|"..the way in which I plan to detect organic matter is to burn it."-- Colin Pillinger, principal scientist, with BeagleCredit: ESA/Beagle
AM: It's been almost 30 years since the Viking experiments. Why do you think it took so long for somebody to try biology experiments again?
CP: I don't think people weren't trying. I think there were a lot of failures of missions designed to go to Mars. And we don't necessarily know what experiments were on some of those Russian missions. But all of them had to get down before they could do any experiments.
I think the real thing that is driving us back to wanting to look at whether there is life on Mars is something that Viking did that nobody anticipated, nobody planned. It was that they were able to show that we have martian meteorites on Earth and the martian meteorites clearly led us to believe that the conditions on Mars are more appropriate for life than we had believed from Viking. It wasn't that Viking didn't find life, it was that they thought the conditions were just so horrid, so harsh, nobody anticipated that life could exist there.
The discovery of water in martian meteorites was made just after Viking. Of course, we didn't know then they were martian meteorites. But we found evidence of water trickling through martian meteorites, we found carbonates in martian meteorites that was definitely indigenous. And we found organic matter.
I believe that the organic matter is there in an amount that can't just be explained by contamination. However, I can't prove it. And if I can't prove something, I just simply say, right, what are we going to do next? Go find another experiment.
So we think we've got a lot of exciting things that Mars can teach us, and we've designed an experiment and a space system that is going to answer the question that we've raised. That's all we can do, is design the best experiment we can do.
And I don't mind if it finds something completely different. One of the great things about science is that you never can predict all the answers to the experiments. You always get some things that you haven't anticipated. And therein is the way knowledge progresses. If you could predict all the answers, it would be really boring. Dreadful. I'd go and do something else like become an accountant. And I've got nothing against accountants.
AM: Why do you think it was ESA that did this and not NASA?
|Close-up of a Mars meteorite, showing what some argue appears to be fossilized evidence of ancient microbial life.
Image Credit: NASA
CP: 'Cause I told them they had to. ESA didn't want to take this lander at first. They were anticipating that they were going to recover Mars 96 with a launch which took place in 2003 while Mars was [nearby] and therefore it was feasible for them to do it. It was me who went there and said, hang on guys, since Mars 96 was designed, we've had all this stuff come from Mars meteorites, and the evidence is very compelling that we dismissed life on Mars too soon. I think we should go back with a lander.
And they said, we don't have the money, we don't have the technology, we don't have the time.
And I said well, I think the public want to know so much about this - this was just after the martian fossil story [the discovery of fossil-like structures in the martian meteorite ALH84001] - that I think the money can be found from somewhere. And I'll go find it.
I went back and talked to a lot of people, and I said, are you prepared to work on a project that's going to Mars with no money, so we're going to have to get out there and try and convince people to give us some? And they said, we don't want to miss this chance of going to Mars. We'll join you. And companies joined me, and universities joined me and individuals joined me and even little old ladies rang me up and said, we think you're doing great.
So that's the reason why we're doing it. It's the Beagle team that's sending a lander to Mars, and we've convinced ESA - and that wouldn't have happened without a review from NASA - that we were a technically sound project, and what's more that we had a scientifically exciting project.
Both of those things are important. This is not a me-too mission. It's not just, can we land on Mars and take a picture? This is hot science that is going to be done using high-class technology, and everybody in this project has contributed to that.
Related Web Pages
Where is the Mars Express Now?
Where is Spirit Now?
Five Year Retrospective: Mars Pathfinder
Open University: Beagle
Space Research Centre: Leicester
Mars Express PPARC