Meet the Scientist: Dr. Matthew Golombek|
Geologist, Mars Pathfinder Project Scientist
by Vesna Nikolic
Q: What are your main research interests?
A: Iím a planetary geologist, and basically, Iíve been mostly interested in Mars geology. Right now, the research Iím doing involves interpretation of data from the Mars Global Surveyor, and Mars Pathfinder mission. Specifically Iím working on structural features that are seen in the MGS data, and Iím interested in surface characteristics and rock distribution as seen in the MP data.
Q: How did you choose your field of interest?
A: I started as structural geologist, and I started looking at structures on Mars. That sort of developed for a while. Then with a chance to work on the mission, I started really thinking about how surfaces vary on the Red Planet and how you can predict what that surface would be like based on remotely sensed data. Thatís of particular interest when youíre selecting a landing site for a spacecraft, because you want to make sure to the best of your ability that the surface that youíre going to land on is acceptable for your lander and itís capabilities. I spent a tremendous amount of effort on Pathfinder worrying about the landing site, and Iíll be working on the future landing sites for the upcoming Mars mission, using the same sorts of techniques.
A: A lot of it is determined by the engineering capabilities of the spacecraft. For example, for Pathfinder, it arrives at the outermost atmosphere of Mars, and it goes through a complicated phase of using an aeroshell to lower itself down, then a parachute comes out, and basically, you need a certain amount of time and the density of an atmosphere to slow the spacecraft to the correct terminal velocity. So, elevation is very important, because you need enough atmosphere to slow your vehicle down to the speed that it needs to be going at. So, you canít land above the certain elevation. In addition, most spacecraft are solar-powered, and so you want as much power as you can possibly get, and so you wind up landing near what we call "sub-solar latitude" on Mars, which is basically near equatorial within 25 degrees or so. And then, you go through all the other things. If the spacecraft is susceptible to landing on a rock, and hurting its underside, if it has legs like Viking, or the airbags on Pathfinder qualify to a rock of a certain height, then you worry about the total number of rocks, and their distribution and their height. And thatís a trick, since you donít have a lot of information about that. Then you worry about dust. Too much dust is probably not a good thing. It might foul up the solar panels; your rover might sink into it for example. And you may want rocks for analysis and so on. Then you worry about science that itíll do and thatís terror to what instruments you have on board the spacecraft. So, itís a very involved task.
Q: You were the Mars Pathfinder project scientist. How was the job assigned to you?
A: Basically, with each project thereís a project manager selected, and a project scientist selected. Those are the first two people, and they are the two people that lead the mission and the project effectively. Basically, the project manager is typically an engineer who has overall responsibility for the fabrication of the spacecraft, keeping it on schedule. And a project scientist to make sure that the science basically stays on the mission during that building process. In a sense, itís two different groups of people - thereís a whole group of engineers that know how to build things, but really donít know much about Mars or what you want to measure there, and a whole group of scientists that probably couldnít build anything even if they had to, and donít really know how, but theyíre really interested in learning something about Mars. And obviously there has to be a marriage of those two. Basically the project scientist and the project manager work together to make sure that happens properly. Now, in a more detailed sense, the engineers for example need to know the environment that they will be landing in - what are the temperatures, what are the pressures, how much atmosphere is there, where can you land, what are the surface characteristics. Those all go in the design criteria for a spacecraft and basically the best people to answer those questions are scientists that know about the planet. Alternatively, as I said, engineers are the best for building things and clearly, the scientists need to work with them to make sure the instruments can function properly on the spacecraft. So basically, those two people are appointed by JPL and NASA to carry out that function.
A: Iíd say thereís about half a dozen key things that were really critical that we learned with Pathfinder. To put them in the broadest perspective, I think the Pathfinder is showing us a planet - Mars - that may have been more Earth-like early on in its history than it is now. Right now, Mars is a cold, dry, dessicating place and we found quite a bit of evidence to suggest that it may have been warmer and wetter in the past. And those key discoveries involved looking at the surface and interpreting the history of how that surface developed. And we believe that surface was deposited by catastrophic floods in the past and so the rocks that we saw on the surface actually looked as if they were water worn and deposited by running water in the very distant past. We found very magnetic dust that suggested that that magnetism occurred by deposition of the liquid water. We measured the moment of inertia of the planet, which gave us bounds on what the diameter or the radius of the internal core of Mars is and if it had one. We really had no direct measure of that prior to Pathfinder. And those were the key things. We found that the atmosphere was much more dynamic than we ever expected, with small dust devils as well as clouds and variety of other things.
Q: Now that NASA has slowed down with Mars missions, what do you think is the future of the Mars exploration?
A: We lost two missions in í98, and in a sense it has slowed down - for example weíll have only one orbiter in í01. Thereís a period going on now where thereís a re-evaluation of what we ought to be doing next that fits within the budget and that wonít obviously fail as the í98 missions did. So maybe we paused, maybe thatís the right word, to make sure that weíre doing the right thing in the right order, and Iím sure weíll be pressing on. I think the reason that Mars is such a compelling place to study is that we may be able to answer one of the most fundamental questions that we as people would want to know, and that is: are we alone in the universe, will life form anywhere that has stable liquid water, which is the absolute key to life, or is something else required? So, if we go to Mars and we see that the early environment wasnít in fact warmer and wetter and life did not develop there, well then weíll have to pause and say "Well, gee, what was so hard about it? Why didnít it?" On the other hand, if we go there and find that it did develop and that the conditions didnít persist, then we would know that life can form pretty much anywhere, and so it allows you to study in a scientific matter what I think is a compelling question that many, many people would want to know, and I donít think weíll stop doing that just because of a little set back here.
Q: Do you have any final words of wisdom for youth interested in Mars?
A: Follow your heart. Everyone develops at different levels, speeds, at different times in their life. I donít think I was a particularly outstanding high school student. Thatís OK. If youíre really interested and excited in planetary exploration, you should go for it, but you should also be very aware of what the limitations are of any career path that you decide on. If thatís a thing that really makes you happy, then you should do it, but you should make sure youíve learned as much as you can about it, before you just leap into it.