Friday, January 26, 2007
NASA: Mars Rovers Turn Three - Interview with Steve Squyres
Steven Squyres , professor of astronomy and NASA's principal investigator for the Athena science packages carried by the two Mars rovers (Spirit and Opportunity), is interviewed by Jane Platt: listen to the podcast here (transcript appended below).
NARRATOR: Three years old, and the Mars rovers are getting even smarter. I'm Jane Platt with a podcast from JPL - NASA's Jet Propulsion Laboratory in Pasadena, California. Our guest today, Dr. Steve Squyres of Cornell University, the principal investigator for the science instruments on the twin Mars rovers, Spirit and Opportunity. The rovers are marking their third year operating on Mars this month. Steve, thanks for joining us, and it's kind of an amazing milestone.
DR. STEVE SQUYRES: Yeah, I'm frankly astonished. I mean if you had asked me three years ago, heck if you had asked me two years ago, if we were going to make it to this point I would have said no way, and they're still doing astonishingly well.
NARRATOR: So you really kind of have way bonus overtime, I mean you're getting to do a lot of things and study a lot of things and find out things that you never dreamed.
SQUYRES: We are and a key point there is that Mars keeps throwing new stuff at us. It's not like we're seeing the same things again and again. We've just seen the most spectacular vistas that the Opportunity rover has ever seen just in the past few months. Far more spectacular than anything we'd seen prior to this. So Mars keeps giving us new things to look at.
NARRATOR: The rovers will be able to do some new things, thanks to some recently uploaded software. Tell me what they'll be able to do that they couldn’t do before.
SQUYRES: Yeh, we taught them some new tricks, ya know when you spend enough time working in what used to be an unknown environment, you learn new things that you'd like to be able to do, and we've given the rovers some new capabilities. One of the ones that I love is something that, we call it "go and touch." For a long time we've done a maneuver that we call "touch and go." In "touch and go," you reach out with the arm and you make a measurement with the arm. And then you put the arm back where it stows away and you drive. But in a "go and touch," what you do is the opposite of that. Let's say there's a rock that's 10 feet away that the science team is interested in. Normally what you'd have to do is take two full days to do that, you'd have to drive to it, once you get there you take some pictures that show where the rock is, send them down to Earth, we look at the pictures, decide how do we deploy the arm onto the rock, and then we go ahead and do it on the second day. With "go and touch," we can just tell the rover, "Okay, we want to see, we want the spectrometer to be placed on that rock," and it will drive over to it and place it all in one day. Huge timesaver. Another one is, of course, there are these wonderful dust devils, right, the dust devils, these little Martian mini-tornadoes that go whirling across the plains. And the way we used to do these spectacular dust devil movies in the past is we'd just take lots of pictures and hope that a dust devil would show up. And sometimes they would, and most of the time they wouldn’t. And we'd waste all these pictures that had nothing in them. What we've done is we've taught the rovers how to find dust devils on their own, to take a picture, evaluate it, if it thinks there's a dust devil it'll send the pictures down, if not, it doesn't bother us with them. One of the new software tricks that we've got is vastly improved navigation, this thing could, the rover could actually sort of work its way through a maze now, if it had to, by kind of going down blind alleys and then figuring out how to retrace its steps and going another way.
NARRATOR: Last time we had you on one of our JPL podcasts was a year ago when the rovers were marking their second anniversary on the red planet. And here we are a year later. You at that time had kind of brought us up to speed on what the rovers had accomplished so far. Bring us up to date now, this past year, what have we learned?
SQUYRES: Okay. The big accomplishment for Spirit this past year has been that we finally reached "Home Plate." Home plate is this feature, man, we spotted that thing from orbit years ago. It's a really interesting feature within Gusev crater, it’s a plateau of layered rocks, it's the best outcrop of layered rocks the rover has ever seen. And we got a chance to explore that pretty thoroughly. What we've concluded is it was probably the result of a volcanic explosion. If volcanic lava comes into contact with water, say, that water will flash into steam, and you'll get this explosion, and you can get a deposit very much like what we see at Home Plate. The big achievement for Opportunity is we finally made it to Victoria crater. That was a 21-month drive, to drive that rover through terribly difficult terrain. It was just an unparalleled exercise in mobility on another planet. And finally after driving all those months and all those kilometers, we pulled up to the rim of the most spectacular feature that either rover has ever seen. And we're not just there for the scenery. This thing provides a deeper, broader window into the subsurface of mars and exposes more rocks than anything we could possibly hope to find with this vehicle, so we've got this geologic treasure trove that we're just barely beginning to explore now.
NARRATOR: Okay, let's take what you’ve learned in the past year and then add it to the previous two years. If you at this point had to write a little tour brochure for Mars, how would you describe the destination?
SQUYRES: The two destinations that we've been to are dramatically different from one another. The picture that we've put together of what Gusev crater, where Spirit is, long ago, what that place was like, it was a violent world . This was a place that was dominated by meteoritic impacts, effectively creating huge explosions that would throw materials into the air, volcanic explosions were going on. There was water, but it was mostly water beneath the ground, these impact craters and these volcanic vents would create explosions of steam, I mean it was a very violent place. In some respects, it had the characteristics that would have been favorable for life, there were probably hot springs, for example. But it wouldn’t have been a very nice place to be. Meridiani Planum, on the other hand, where Opportunity is, the geologic record that we see there preserved in the rocks is more quiescent, it's a place that was pretty dry most of the time. There was a lot of water beneath the ground. And when I say water, what I really mean is sulfuric acid, you wouldn't want to drink this stuff. But there was this acidic water beneath the ground, it saturated the ground, and it would occasionally come to the surface and form pools and ponds and perhaps little streams, evaporate away and when it evaporated away, it would leave salt deposits behind. And then these salt deposits would blow in the wind, and they would form dunes, and we see the record of those salty dunes preserved in the walls of Victoria crater. So it was not exactly an evolutionary paradise either, there was acid, it was dry much of the time, but it's the kind of environment that would have been definitely suitable for some simple forms of life.
NARRATOR: So there has been a lot learned, obviously, from these two rovers, which by the way, we don't know how much longer they will continue to operate.
SQUYRES: They could last another three years or they could die tomorrow, and there's no way of telling. We try to live every day with these vehicles as if it's the last. You drive them each day as if there literally is no tomorrow, because that could be the reality, so we're pushing them very hard, we're pushing ourselves very hard.
NARRATOR: And at whatever point they are no longer with us and functioning, other spacecraft up there already, more in the works.
SQUYRES: Oh, yeah, yeah. I mean, we've got this wonderful synergy going on right now among four different JPL spacecraft that are at Mars. You’ve got the two rovers on the surface. They're communicating with us daily, relaying information through the Mars Odyssey orbiter. And then at the same time, we have the newly arrived MRO, Mars Reconnaissance Orbiter, that's up there, taking incredible images where you can see the rovers on the surface, and we daily use that imaging capability and the pictures that MRO has taken of our sites to plan our operations. And, of course, the scientific discoveries that are coming out of all the instruments on the Reconnaissance Orbiter right now are just fantastic. You’ve got phoenix, the next JPL mission that's going, which is a lander.
NARRATOR: That's this summer.
SQUYRES: It's going to launch this summer, its going to land near the north pole of Mars and follow up on a discovery from Mars Odyssey that there's ice close beneath the ground at those latitudes, dig down into the ice and see what's in it. And then one of the ones that I'm really excited about, because I'm a rover guy, is you got the Mars Science Laboratory, MSL, in 2009, which is a bigger, beefier, better version of Spirit and Opportunity. It could last, it's designed to last a full Martian year, it's designed to go for very long distances, carries just a spectacular payload of scientific instruments, a lot of the things that I wish we could have had room to put on Spirit and Opportunity. So it's just gonna keep going, it's great.
NARRATOR: And just to sum up, I guess we can't reiterate enough times, the reason we're doing all this, what we want to find out is?
SQUYRES: Whether or not, Mars, which today is a cold and dry and desolate world, ever has harbored life, and find out whether or not we're alone, in the solar system and in the universe.
NARRATOR: Alright, well thank you so much for your time, Steve... You've been listening to a podcast from NASA's Jet Propulsion Laboratory.
Source: NASA 01.17.07 (Abridged)
Steven Squyres co-authored this paper from the journal Science:
Science 5 August 1994:
Vol. 265. no. 5173, pp. 744 - 749
Early in its history, Mars underwent fluvial erosion that has been interpreted as evidence for a warmer, wetter climate. However, no atmosphere composed of only CO2 and H2O appears capable of producing mean planetary temperatures even close to 0°C. Rather than by precipitation, aquifer recharge and ground water seepage may have been enabled by hydrothermal convection driven by geothermal heat and heat associated with impacts. Some climatic warming was probably necessary to allow water to flow for long distances across the surface. Modest warming could be provided by even a low-pressure CO2 atmosphere if it was supplemented with small amounts of CH4, NH3, or SO2. Episodic excursions to high obliquities may also have raised temperatures over some portions of the planet's surface.
 James F. Kasting is author of "Habitable Climates":
"One of the fundamental requirements for life as we know it is the presence of liquid water on (or below) a planet’s surface. If one is interested in detecting life remotely with Terrestrial Planet Finder (TPF), then it is important that the liquid water environment be in contact with the planet’s atmosphere, as it is only by potential biological modifications of atmospheric composition that we can can hope to do this. Possible subsurface liquid water habitats such as those that might exist on Mars or Europa are interesting with respect to our own Solar System but would be difficult or impossible to investigate on planets around other stars."
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