Touchdown! Dean of Science Laurie Leshin Interview


At 1:32 a.m. Eastern time, the NASA rover Curiosity safely touched down on the surface of Mars after a journey of more than 300 million miles and a harrowing descent from orbit, complete with parachutes, rockets, and the perilous ”sky crane manuever.”
As a member of the science team for Curiosity, Rensselaer Dean of Science Laurie Leshintraveled to California for the landing, and is currently at the Jet Propulsion Laboratory helping to analyze data from the rover. An opinion piece Leshin wrote about the importance of the mission, and the hope that it will engage young people in the pursuit of math and science, appeared in Sunday’s edition of the Albany Times Union.
Before she left, I had a chance to speak with Dean Leshin about the mission and her work as a member of the science team:
What’s the Curiosity mission all about?
Curiosity is all about trying to understand the habitability of an interesting site on Mars. It’s about discovering the potential for life in this very interesting place. The interesting-place part is important because the rover has the capability to land much more precisely than anything else we’ve ever sent to Mars. That means we can snuggle right up to an interesting mountain. In this case we’re landing on a plain near a mountain which we would not have been able to do with Spirit or Opportunity or one of the Viking landers. It’s got the capability to drive a long way, so we’re going to drive up the mountain.
The mountain is interesting because it’s full of layers. Layers are golden to a geologist because that means you have a time sequence, much like the layers in the Grand Canyon—which go from the oldest at the bottom and the youngest at the top. We’re going to march up those layers and study them along the way. It will be like reading a book from beginning to end of this time period in Martian history.
You helped plan two of the 10 instruments aboard Curiosity. What are they?
The science team decided that, not only does Curiosity needs to be able to do field geology—to understand the site that we landed in and look at it from a geological perspective, it also needs to be able to chew on some rocks and understand what they’re made of in detail. Curiosity has got great ability to interact with rocks and soils.
The first instrument that I helped to prepare is a remote contact instrument called an alpha particle X-ray spectrometer,or “APXS” affectionately. You just set it down on a rock or soil and and it can analyze the bulk chemistry of that material, telling you how much silicon, magnesium, or iron are in that material—which gives us an indication of how the rock was formed. The way this thing works, it’s got a radioactive source (a little bit of curium), and it bombards the sample with alpha particles, those generate xray response from the material itself and those xrays have energy which are indicative of the material. So you get a peak for silicon and a peak for magnesium and a peak for iron. And so you get this fingerprint for what’s in the sample and the size of the peak is related to how much of it is there.
The second instrument is called the Sample Analysis at Mars, or “SAM.” SAM is an amazing instrument. It’s a box about the size of a microwave oven, and it has 72 little ovens inside of it—little tiny cups that can be fill with ground rocks or dirt and heated to 1,000 degrees celsius. Any volatile materials trapped inside of minerals, or ice, or water, will be released and can be analyzed in a couple of different ways within the instrument itself. That’s the instrument that will tell us whether or not there’s organic matter at the site on mars.
SAM will be looking for preserved organics. It has a mass spectrometer and a gas chromatograph and both of those things detect the organics.
What do you hope Curiosity will discover?
I think it would be exciting to discover organic materials. We know there must be organics on Mars—they’re falling from the sky, all the time extraterrestrial materials are raining down on Mars just like they rain down on Earth. If we don’t find any, that means there’s a darn good way of destroying them on the surface. Which could be possible, but with this very sensitive instrument, if we don’t find them, that’s really saying something about the habitability of the surface. It’s a harsh, harsh environment.
I also hope we find a lot of water-bearing minerals that we can characterize very well—carbonites, clays, sulfates—and that can teach us about the aqueous environments on Mars. For most of my career we’ve thought about Mars as a cold dry place with a potential for a warmer weather past, but not a lot of evidence of it. But that’s changing and I think this mission has the potential to really start painting a picture of a more habitable Mars from the past and its potential for habitability in the future.


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