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To MARS with MER - MER the Mission

Joy Crisp
Mars Exploration Rovers Project Scientist
NASA Jet Propulsion Laboratory

"December 12, 2002"

P2K: Up in San Francisco (at a press conference at the Fall 2002 Annual AGU meeting), Steve (Squyres) gave the party line that you're (NASA's Mars Exploration Rovers mission ) looking for "environments." Matt (Golombek) went a little bit further; he said that you're looking for evidence of biotic or prebiotic environments. Which is it - is it rocks, or is it life?

Joy Crisp: The emphasis here is on the word environment. We don't have any instruments on board that really are designed for looking for life. They're really designed to do geology and identify minerals, and those minerals hold clues to past environments, and that will tell us something about whether these environments were conducive for life or not.

P2K: What's the connection between environments and rocks and the possible evidence of life that you might hope to find?

Joy Crisp: The connection is that... rocks hold clues to the past environment that's locked in the kinds of minerals that are present. They tell us something about how warm it was, or how cold it was, how wet, and whether there were hydrothermal fluids bubbling through the rock, or cold lakes, how long the water was around. And that's going to tell us something about the likelihood of life having been there, whether it was short-lived or whether life could have been around for a long time.

So there is somewhat of a jump, because we're finding a lot of life in extreme environments here on the Earth. But if, on the other hand, we find that for two billion years Mars, in the past, was warm and wet, then that will tell us that there's a good chance that life may have formed there. Whereas if we find that it was very harsh throughout its whole history, that's another story saying, Boy, it might be very hard to ever find evidence of life on Mars, and if it was there, it was very hardy forms of life.

P2K: One of the things that makes the Mars Exploration Rovers mission such a fascinating mission and so good in terms of education for kids is that you guys have a bunch of hypotheses, and the entire mission is like a scientific experiment to try and find the answer. What are some of the key hypothesis that you guys are trying to test with the Mars Exploration Rovers mission?

Joy Crisp: Well, they vary from landing site to landing site, and we're actually still working on those. I can give you some examples.

At the Hematite site (now called Meridiani Planum, and the designated landing site for "Opportunity", the second rover to arrive at Mars) there's a mineral there called "coarse-grained hematite" that we have identified from orbit. And the hypothesis is that that mineral formed in the presence of water. We have a lot of instances of that happening on the Earth. But we're not exactly sure, and if it was formed in the presence of water we're not sure whether it was warm or cold water, and in what form it was, how long it was around. So the hypothesis is to go there and look for the other minerals that are there with the hematite to figure out how that rock formed and what the water process was like. So that's the main testable hypothesis at that site.

At another site, called Gusev Crater (landing site for the "Spirit" rover, due to land on January 4, 2004), we have evidence that it looks like water flowed into a crater, ponded there for some time, and deposited sediments. So the hypothesis there is, can we find evidence for that, and did that really happen, and what was it like? Did minerals precipitate out of the water? Did things deposit out physically out of the water? What was it like? We need to look for clues to test that hypothesis.

P2K: Let's transition to the site selection process.... You guys talk about it as an open community process, the "science community." How happy are you with the process that's led to the shortlist of sites?

Joy Crisp: Very pleased with it. We've had a lot of effort put in by scientists around the world that study the data much more than we can do, and they look at these individual sites very carefully, and come up with new hypotheses and maps and detailed evaluations of each site. And that's been very helpful to us. So I've been very pleased with the effort that's gone on in these workshops where we air all these issues and get to hear all the different ideas about each site.

P2K: This is not meant to be a snotty (i.e. impertinent) question, but you and Matt and Steve and everybody else have your own favorite sites. Did the process end up with you guys considering some sites that you never would have come up with as a shortlist of your own?

Joy Crisp: Uhm, actually, I don't know that we have favorite sites. So we're really working hard just to find the best site. It's hard to find sites that actually meet all of the engineering criteria, and that have some science value that will allow us to meet our science objectives. So I think we're all just in the mode of being grateful that we have four sites at this point that do meet those criteria. (See BOUNCING TO MARS for scenes from the 2nd site selection meeting.)

P2K: Think back to some of the things that have happened in these site selection meetings. There's a lot of debate. People get up, they say, "this is the site that you really should go to." The engineering folks get up and say, "this is what the rover can do, this is where you can land safely." And then you guys ended up voting on a shortlist of sites. What's going on in those site selection meetings, from the insider's perspective? As you sit there, what are you thinking, what are you seeing going on?

Joy Crisp: Well, you know, everybody is coming to a consensus, essentially. In the third workshop we did something interesting. We had a long list of criteria, pros and cons of the science, of the safety, and even of the "outreach value" of each site. And we came to a consensus of whether we should color code it green as "good," yellow as kind of okay, and red as "poor." And we all agreed to what the color should be on these items. And then when you looked at the full list of sites and what the color dots look like for each one, it was quite apparent that several of the sites had some bad aspects to them. And everybody came to a good consensus that those sites should be dropped. So I think it's been a very good process and everybody understands why these decisions are being made, because they can see some safety criteria are getting too risky and they agree, even though some of the sites had high science advantages, they all understood, because the engineers stood up and gave talks on how this system could fail on landing, and they understood how we decided that they were unsafe. So it's been a very good process.

P2K: As a scientist, do you get irritated or upset if the engineers put some constraints on places that ideally you'd like to go?

Joy Crisp: (laughter) Oh yeah. It is aggravating sometimes. You want to go somewhere. In fact, many of us were keen on the Melas landing site in Vallis Marineris that would be very fun to go there, and it had very interesting photographs that we had from orbit of that site. However, we all realized that it was very unsafe. Once we got the digital terrains from that site (it was clear) the slopes were too steep, the winds that we predict going through that canyon at the time we would land were unsafe as well. You know, you only can do so much with a short amount of time and make the launch, and this is truly the best that we can do. So, yeah, you want to go elsewhere, maybe, but you can only do so much.

P2K: One of the things that came out of some of the technical reports in the second site selection meeting was just about everywhere was unsafe, that Viking I and Viking 2 and even the Pathfinder landing site might not have been selected if you'd known as much as you know now.

Joy Crisp: Well, you know, that's the trouble. We have so much more data now than we had when we picked the site for Pathfinder, and, unfortunately, that means... when you know more about Mars in terms of the rock abundance, the slopes, the terrain, the winds - things that we didn't know before - we're learning that Mars is a difficult place to land on. But this is a reasonably robust system and we do have four candidate landing sites. That's good.

P2K: What was interesting is that each of the people came, Nathalie (Cabrol) came, and at that point Gusev looked like a dark horse candidate; it didn't look like a prime landing site. Do the scientists get personally invested in a particular site when they're making the case for it?

Joy Crisp: Yeah. Some of the scientists do get very wrapped up. They've invested a lot of time and they may feel that this is really good site and they want to go there. So, that's a good thing. Then you have a person who's an "advocate" for that site. And we also have other scientists that work on the sites that are maybe less invested, that they also look at the sites and give their interpretations. So we combine all of that at these open workshops and get to hear all sides of the issue. I think we've aired all the pros and cons of each site.

P2K: I think kids might be amused to see, and I was amused to see, people actually voting at the end of the second site selection and the votes being tallied up. Was that really voting to see what the shortlist was going to be?

Joy Crisp: Well, that's what happened in this second workshop. We did vote and tally them up. That's actually how it was done for Pathfinder. In the final selection there was a small group of people who voted. But in the voting there was also somewhat of a feel of a consensus. You could look around the room and see,OK, this is overwhelmingly the way the votes are going.

I think in the third workshop I liked that approach better, where we ranked things yellow, red, and green, and then looked at the results and all felt like that made sense. So I think that's a better way.

What we really need is to bring to NASA Headquarters, when they make a final decision in April, we want to explain to the Associate Administrator for Space Science what the workshop consensus was, and whether it was overwhelming, or half and half. We need to get that information across to Ed Weiler (see his comments in the final segment of BOUNCING) so he knows, okay, here's how the science community feels. So if that's by a vote and then we're explaining how that vote breakdown was, or that we all agreed to a particular ranking or rating of the sites' characteristics, that's the kind of information we need to pass along. We wouldn't just give (NASA) the final result, (saying) these are the top ones. We want to explain to him how the science community feels. And we also want to explain how a group of tough peer reviewers feels about our assessment of the safety and science. We also have a steering committee that was selected by Headquarters, and we want to let him know how they felt about it as well.

P2K: What's the big plus of each of those sites?

Joy Crisp: Well, first of all, the big plus of all sites is they meet the safety criteria, and that's a big one. So for Hematite we have mineralogical evidence of probable past water activity.

At the Gusev crater we have good evidence from Viking imagery of that crater; it looks like water ponded there in the past.

And for the Isidis site it looks like highlands, ancient highlands material, may have been eroded and carried down into the (landing) ellipse. We're still trying to figure that out and whether that's the right hypothesis for that site. An alternative might be that sedimentary units were imbayed [sic] onto the highlands at the base of the highlands, and so there could have been past water activity that way.

And finally there's the Elysium site (referred to as "Athabasa" during the site selection meetings), which was selected primarily for safety, but it looks like ancient degraded highlands material. So we may be able to ask the question, "was Mars warmer and wetter in the past?", by looking at those rocks.

P2K: The other big thing that happened last summer was the field tests. What was happening in the field tests? Where was the rover, and how did they explore it from JPL?

Joy Crisp: That was a very interesting experience where one person selected a site and didn't tell us where it was, and set the rover out in the desert somewhere unknown to the whole rest of the team. (Scenes of the so-called FIDO test appear in P2K's COUNTDOWN TO MARS program, narrated by mission manager, Nagin Cox.)

And the team had to operate a test rover called FIDO, which is about the size of the ATHENA rover, having similar instruments on it, but not the same. And they had to look at pictures that came back from this test FIDO rover and decide what to do the next day and try to test hypotheses, work together as individual science teams and interact with each other, prepare the uplink command sequence for the next day, and cycle through two Martian days per Earth day. And that put a lot of pressure on the teams. We wanted to simulate that pressure somehow, and we did that by making the schedule very, very tight. So they were using some prototype software which will be sort of like the software they will use to command the Mars rovers. So they got to practice that and look at images and try to do geology remotely with this rover.

P2K: Were you a participant in this, or were you sort of supervising and looking at how things went?

Joy Crisp: I was watching how things went. I also was working with a student intern. We were practicing a couple of other things. One was the student intern program that they want to have during operations, so I was a mentor for one of the students, and we tested out how that might work during operations. And they were also testing out the outreach. By that I mean the information that would go out on the web and to the press. So everyday they called on a couple of scientists to write bigger captions and put things out on the web. So I was watching how all these things were going because I'm part of the decision-making on how we're going to do operations and how well things are working.

P2K: How good was the characterization of the remote site done by the experiment?

Joy Crisp: Well, they got some things right and some things wrong, and that's to be expected because you have a limited resolution of cameras on the rover and you can only look around so much. You get a limited set of data back. So I was impressed and I think they got a lot of things right about how the rocks formed that they were looking at.

P2K: What was the biggest lesson that you, from a management point of view, learned as a result of FIDO? What are you going to do differently when you're actually on Mars?

Joy Crisp: Actually, I can't think of anything I would do necessarily differently. I felt it was a very good introduction to field geology done remotely. And I was impressed at how well the team worked together and interacted, and I think that's a good sign that they're going to work well in the operational tests for the Mars rovers.

P2K: I think I've been impressed by just how much forethought is going into surface operations. Years ahead of actual reality there have been the tests and experiments and so forth. Is this unusual for a mission, or is this what needs to be done for any big mission like this?

Joy Crisp: It needs to be done for a big mission like this. It's highly complex and there's a lot of people, and the timeline for doing operations on a day-to-day basis is very compact, so you have to plan in advance what each person's role is going to be and how they're going to step through their procedures, what software tools they need to use. And way in advance you have to train them on the tools and have them use the tools so you can find out if the tools really do what they really need to do, so that you have time to change those software tools so that they will work well during operations.

P2K: Between the time we first talked (September 2001) and now you've brought on a lot of new science investigators. What's the key characteristic about a science investigator you'd want to have on your extended team? What qualities of mind?

Joy Crisp: Number one quality that's good is to have somebody coming to the team that wants to help. There's a lot of hard work involved in operations. At our first science team meeting we had each new team member stand up and introduce themselves, and I was so happy when several of them stood up and said, "I want to help, I want to be involved in calibration and testing and I want to do everything I can to help the team." And that was a really good feeling.

And at the same time, the ATHENA team members were telling the new team members that you're now part of this team and you're going to be treated as an equal. And so that really helped build a good team feeling.

P2K: Scientists are sometimes pretty convinced that their ideas are better than anybody else's. Do you feel as if you're herding a crowd of cats?

Joy Crisp: Yeah, it's tough, because everybody has their own science investigation that they're trying to carry out. But in the FIDO field test it was clear that everybody had built up a respect for each other. So the geologists were okay with letting the atmospheric scientists come up with things to do. And, meanwhile, the atmospheric scientists were letting the geologist do some too. So everybody recognized that they have to work together, and let everybody get a bit of their own science done, and work as a group.