Transcript of the chat held on March 4 with Dr. Bell, planetary scientist from Cornell University

Dr. Bell holds a Ph.D.in Planetary Geosciences from the University of Hawaii at Manoa. He is a Research Associate at Cornell University, Department of Astronomy, Center for Radiophysics and Space Research and Visiting Astronomer, NASA Infrared Telescope Facility for NASA Near Earth Asteroid Rendezvous (NEAR) Mission.

Question : Ok. Jim : first question. What should we start thinking about in order to choose a good landing site for our mission?
Answer : A good first question!
You need to think about several issues:
(1) What kind of science or exploration do you want to do?
(2) Where CAN you land? (are there engineering/technical limits?)
(3) Can you be 100% sure that you can land there and return safely?

Question : What about the chaotic terrain in the S hemisphere?
Answer : Yes! The southern hemisphere is the oldest terrain, and there are several good choices for places to look there.
Possibly better than chaotic terrain would be ancient lakes, like Gusev crater near 15 deg. S, 185 deg. W. Most scientists believe that Gusev was once filled with water... and who knows what else!
OK; let's start with goal #5 because that addresses science.
IF you want to find life on Mars, then you want to look in some very specific places. I assume that many of you are familiar with last year's famous "Mars meteorite" story... ?
Well, the upshot of the Mars meteorite story is that it comes from a very old region of Mars. You mentioned floods: well, evidence for water on the surface also occurs primarily in the oldest regions. All this leads one to conclude that Mars was very different long ago...
So while it would be VERY cool to land on the top of Olympus Mons or in the deepest part of Valles Marineris, we know that these are relatively young places. If the goal is searching for past (or present!) Mars life, then the places to go are probably the oldest places, where evidence for life may be preserved as fossils from a time when Mars was warmer and wetter than it is today...

Question : Wouldn't it be too risky to land on Crater Lake (too small a target for a lander)?
Answer : Landing accuracy is constantly improving for the robotic missions. But just look at Apollo 17 as an example: skilled astronauts and an excellent spacecraft allowed them to plunk down in a very small valley between two huge mountain ranges on the Moon. Gusev is something like 150 km
across, so maybe there's plenty of room for a skilled pilot to land there...

Question : What about choosing a site that can enable us to explore both ancient and 'new' terrain?
Answer : Ancient and new terrain in the same area is a tough order. But there are rregions along the boundary between the southern highlands and the northern lowlands that might work. Another approach might be to give your landed crew some mobility of hundreds of kilometers,
with a Marscar of some type, or a balloon, or a plane, or make the lander capable of taking off and landing again somewhere else on the planet...?

Question : What about exploring the polar ice caps? The best record of the Martian climatic evolution could be found there?
Answer : Polar ice caps...
Sure, there is a great record of Mars climate evolution there, but hang on: You said your goal was finding Martian life.
You have to be careful that you stick to your goals, otherwise you are subject to what the U.S. military calls "mission creep" as you wander farther and farther away from what you had
originally intended.
The poles are great places geologically and climatically, but at -120 C they are not very good places for life...

Question : Our goals are temporary, and we are in the process of discussing them
Answer : Aha.... I see.
OK, well then go back to my first few points: Can you GET to the poles? It takes a lot of rocket fuel to get to high latitudes, and you'll have to carry that fuel with you, which means a heavier launch, which means a bigger rocket, which means more money, .... etc etc. Everything is inter-related in the real world of space travel...

Question : Is diverting an asteroid into Mars really feasible as we have been reading about in futuristic articles?
Answer : Diverting asteroids is not feasible given our current level of technology because (a) we don't know enough about asteroids (instead of diverting one we could blow it into a zillion pieces!), and (b) it's not clear that there are enough explosives, nuclear or otherwise, on the planet to do the job. Plus you open up a whole can of worms on the nuclear issue. If we have this giant stockpile (again) for supposedly peaceful purposes, who's to say that some tyrant or terrorists won't take it over...

Question : Have you read The Case For Mars? How valid is the book from your perspective?
Answer : The Case for Mars is a very ambitous and enthusiastic book.
In today's world, unfortunately, it really is science fiction rather than science fact, because governments just don't have the money needed to do a human Mars mission.
However, the idea is sound, and it's only a matter of time before something like it takes off. Maybe 10 years? 20??

We would like to thank Dr.Bell once more for his generosity in helping us with this chat. Thanks also to the schools that joined in.

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