Mars - Interview with James Bell, Ph.D.

ccording to our Special Topics analysis of Mars research over the past decade, Dr. James Bell’s work ranks at #10, with 36 papers cited a total of 681 times to date. Two of these papers also make an appearance on our top 20 papers lists for this topic. In the ISI Essential Science Indicators Web product, Dr. Bell’s record includes 93 papers cited a total of 1,975 times to date in the field of Space Science. Dr. Bell is an Associate Professor in the Department of Astronomy at Cornell University. Below, he discusses his highly cited Mars research with correspondent Gary Taubes.

What was your official position on the Mars Pathfinder mission?

I was a member of the camera team; I worked with the folks who designed and built the camera to operate it every day. We took turns doing data processing and data analysis. That mission went from July to about September 1997. It ended when we all sat down to write papers and do the scientific analysis.

Why do you think that 1997 Science paper was so highly cited?

“Some things you just can't predict; you just roll the dice and that's what we did, and it all worked out great.”

That was the initial presentation of results from that mission. It was the first time in more than a decade that we had equipment down on the surface of Mars able to make measurements in an area much more geologically interesting than where the Viking landers went in the 1970s. From orbit, this area looked like it had had some of these massive floods going across the surface at some time in the distant past. We were then able to make direct measurements of the morphology and composition of the rocks probably associated with that. What we saw in that geology was evidence supporting the hypothesis that we had from orbit, that there was a water-rich history on this part of the planet. In a sense, you’re making guesses from orbit because you can’t resolve all the details on the surface. But once we were down on the surface, we could see evidence for this in the geology and in the composition. We saw volcanic rocks, for instance, that appeared to be altered by water and by the action of water, physically and chemically. That was exciting. We also saw evidence for active current weather on the planet. We saw dust devils, clouds, and weather patterns traveling over the landing site. So it was a nice mix of looking at rocks and learning something about the ancient past of the planet and then characterizing the current environment in terms of that meteorology. This was the first time we ever used a rover on Mars. We had this little tiny laser-printer-sized rover able to scurry around and sample some of the rocks and composition, and that helped us put that story together. We weren’t restricted to one spot as Viking had been. The Rover went about 100 meters around the lander and sampled about a dozen different rocks.

Were any aspects of the Pathfinder mission you found particularly lucky or serendipitous?

The landing was probably the luckiest part. We only had 20 percent of the budget of those early Viking projects to work with, and we were using this risky and untested airbag technology: you basically inflate this big beach ball around the lander and then bounce onto the surface. So just getting down on the surface was risky and the fact we survived that was a wonderful thing. I guess you could also argue that because we landed in a place that actually did show some evidence of the stuff we were looking for from orbit—that was somewhat serendipitous, as well. You can’t resolve landing sites from orbit. We could have landed in sand dunes or on a big dusty plain, and we wouldn’t have learned anything about the intrinsic geology. Some things you just can’t predict; you just roll the dice and that’s what we did, and it all worked out great.

What was the hardest part of doing the research? The greatest challenge?

There were lots of challenges. One of the toughest was just operating the machine. Mars rotates at a different rate than the Earth does. The Mars day is 24 hours and 40 minutes long—a little bit longer than the Earth day. We had to be synched up to the Martian day, because the spacecraft are solar-powered. So that changes in Earth time every day. We would be working more or less normal hours and then over the course of 10 days or so, our normal workday would become the middle of the night. So we all got screwed up in terms of our sleep-wake cycle. We got out of synch with the rest of the planet. Spacecraft are sort of unforgiving in that way. They don’t care about day-night cycles, weekends, etc. So we had to adjust our lives to this bizarre interplanetary schedule. It was a grueling thing to go through for several months. Fortunately it all worked out, and we were able to get some good measurements and demonstrate the usefulness of this little rover. That helped to make possible the current missions, which are based on similar rover technology but scaled up by a factor of three or more in range, power, and mobility.

How has our knowledge of Mars changed since the Pathfinder days?

It’s actually changed quite a bit. First of all, we’ve improved immensely our ability to relate what we saw from orbit very accurately to what we see on the surface. We had a companion spacecraft to Pathfinder launched about the same time, the Mars Global Surveyor, and that has been taking high-resolution images of Mars and collecting other data ever since. It has completely revolutionized the study of Mars compared with what we had learned from the probes of the 1970s. We used what we learned from the Mars Global Surveyor to pick the landing sites of the two rovers that are there now. That was based on new information about geology and especially about the role of water in Mars in the past. These gullies, ancient lake beds, mineral signatures, etc., are the kinds of beacons which signal that water was once there. And so these current rovers are taking advantage of everything we learned from Pathfinder and its contemporaries.

What’s next on the Mars mission agenda?

There are three firm missions in the works. After that it becomes a bit of science fiction that we’re still trying to figure out. Another orbiter gets launched next year, and that will continue to incrementally build on past orbiters, with higher-resolution, more-wavelength coverage. A radar sounder will be on it. That launches next year and then there’s another lander that goes up in 2007. That will go near the north pole of Mars and look at subsurface ice deposits and things like that. That will be stationary. The hope is we land next to something interesting. Then the next rover will be in 2009. It will be larger than the current rovers, with more capabilities, more range, and it will have a very highly detailed chemical analysis lab on board to do things like isotopic analysis. It might have some radioactive dating capabilities on board. Proposals are just being submitted right now. That will get there at 2010. After that it’s a subject of an enormous amount of debate in Washington and elsewhere on what to do next. You probably heard about President Bush’s call for returning people to the moon and Mars. Other things on the drawing board include additional rovers and ultimately a robotic sample return, to get some of materials back here before people go there.

Is there anything you wish you had done on Pathfinder that you didn’t?

Yes, and in fact that’s the idea of these rovers that are there now. We wanted more mobility, because we weren’t able to stray very far from that lander back in ’97. We knew we had to go farther, so we built bigger machines that could go farther. We wanted them to carry more scientific firepower. So instead of just one spectrometer and a kind of crude camera system, we have three spectrometers and the highest resolution cameras ever sent to another planet. There were a lot of things we wanted to change and make better and we’ve done that in these new missions that are operating right now.

Is there a last message you’d like to convey to the public about your Mars research?

I guess that we’re doing this kind of scientific work not just for the sort of egghead geeky reasons that we do a lot of other things, studying esoteric issues the like geochemistry of Martian rocks. There are a lot very narrowly focused scientific issues that interest us. But those of us doing it are very aware that’s there’s a very public exploration, education-oriented, future-oriented aspect to this work. That’s why it’s so important for us to do things like put all the pictures on the Internet as quickly as possible. That’s why it’s important for us to get kids and teachers involved and fan their excitement. We’re trying to communicate our own excitement and get the public involved. After all, taxes are paying for this stuff. It’s really our responsibility to carry the public along with it. So far in these missions we’ve had a lot of support. We’re thrilled with the support were getting, both when the missions work and when they fail. We had problems in 1999 when two missions failed, and we still got a lot of public support and a lot of support in Washington to keep this going.

James Bell, Ph.D.
Cornell University
Ithaca, NY, USA

ESI Special Topics, September 2004
Citing URL - http://www.esi-topics.com/mars/interviews/JamesBell.html