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Mars Orbiter Takes Big Picture Approach
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Mars Orbiter Takes Big Picture Approach

Space

Mars Orbiter Takes Big Picture Approach
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JOE PALCA, host:

This is TALK OF THE NATION: SCIENCE FRIDAY from NPR News. I'm Joe Palca in for Ira Flatow. Send a lander to Mars and you can get back spectacular panoramas and close-up pictures of rocks and soil. NASA's two Mars rovers have proven that in spades, but a rover can only cover so much of the Martian surface. To get the big picture you need an orbiting satellite and there are three of those on the job right now. But you know scientists, they always want more detail.

Last week another orbiting observatory arrived and went into orbit around Mars. The Mars Reconnaissance Orbiter is designed to look closely for evidence of water on the Martian surface and among its tools are more powerful cameras than on previous orbiters. While earlier missions could see things on the surface the size of a school bus, the MRO cameras could pick out your dining room table on the surface of Mars, assuming of course you were careless enough to leave it there.

Later in the hour we'll be talking about mad cow disease and new research into asthma, but first its back to Mars. Joining me is Alfred McEwen. He's the principle investigator for the High Resolution Imaging Experiment, or HiRISE, on board the Mars Reconnaissance Orbiter currently circling Mars. He's also a professor of planetary geology in the Lunar and Planetary Laboratory at the University of Arizona in Tucson. Welcome back to the program, Dr. McEwen.

Dr. ALFRED MCEWEN (Principal Investigator, High Resolution Imaging Science Experiment (HiRISE), Mars Reconnaissance Orbiter; Professor of Planetary Geology, Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona): Good afternoon.

PALCA: And if you'd like to talk Mars with us, give us a call. Our number is 800-989-8255; that's 800-989-TALK. And if you want more information about what we'll be talking about this hour, go to our web site at www.sciencefriday.com where you'll find links to our topic. So, any pictures yet Dr. McEwen?

Dr. MCEWEN: No, but ask me again a week from today, actually. Next week we get a few images. These are test images and at higher altitude in non-standard conditions and so forth, but those are gonna be really precious images to us and very exciting for us to see our first images of Mars.

PALCA: So, you haven't had the cameras taking pictures as you approach?

Dr. MCEWEN: No, we do not. We did get a few images of stars and of the moon for calibration on approach. This is not their standard camera that you point and stare and take a picture with like you can on approach. We need a moving target, so in order to take a picture (unintelligible) the spacecraft (unintelligible) stars or you're in orbit around the planet which is what it's designed to do.

PALCA: Explain that. I mean how does the movement of the spacecraft help the camera take a picture or resolve an image?

Dr. MCEWEN: Right. We don't have a choice. We're in a polar orbit. We're making almost 13 orbits a day and we're screaming over the surface at 3.2km per second and we want an image with pixels the size of about a foot square. So, how do you do that? How do you possibly get enough photons to take a decent picture like that, and one option would be to have a really giant telescope that can take in a lot of light and we have a pretty big one, the biggest one that's ever left planet Earth, but it's still small compared to ground-based telescopes. So, what we do instead is we use something called time delay integration where we basically image each spot on the surface up to 128 times and sum up the signal. So, basically we have a very short period of time like 10 microseconds for each pixel, but we do that a hundred times and add up the signal.

PALCA: I see, but this orbit that you were describing where you have several orbits per day, that's what's coming. Right now, as I read, it's taking about 35 hours to make a single orbit.

Dr. MCEWEN: That's right. Right now it's in a long elliptical 35-hour orbit and pretty soon we will start aero-breaking where we dip into the atmosphere to slowly circularize the orbit, so it'll take about six months and then next fall is when the primary science phase begins.

PALCA: Yeah, I was wondering about this aero-breaking, too, because I presume there's not a special surface on the spacecraft that acts as a break. Is it just the mass of the thing as it interacts with the atmosphere that slows it down, does it heat up or something like that?

Dr. MCEWEN: Yeah, well, the engineers spend lots of time and effort thinking about how to orient the spacecraft and how everything is going to heat up and so forth to engineer this correctly so that it'll work...

PALCA: I see, so...

Dr. MCEWEN: ...without damaging anything.

PALCA: And how long before the orbit is circularized?

Dr. MCEWEN: We need to finish in early September and even if we could finish earlier, we don't want to, because we want to finish in a 3 p.m. local mean solar time because that's the right kind of illumination conditions for what we want to do.

PALCA: It's amazing the number of factors that you have to consider as you plan all these missions out. I mean, I was particularly impressed, you know, on some of these outer planet missions where you happen on, you know, on Tuesday you're going past Cassini, I mean, one of the moons, you know, and it's figured out like years in advance. Amazing!

Dr. MCEWEN: Yeah, it's figured out years in advance, although the details, observation sequences, are months in advance. On MRO we don't have that luxury at all. We have to be constantly figuring out what we're gonna do next week.

PALCA: Okay. And you mentioned that this was the largest telescope to leave the earth orbit and to take pictures on another planet. Is that what's happening each time, that the better pictures are coming from larger telescopes, or is the electronics improving as well?

Dr. MCEWEN: Both. The optics are bigger and better than had previously been sent to Mars, although we're not breaking new ground in terms of, you know, earth-based telescopes, that type of thing. The real challenge for HiRISE was speed of the electronics. We have to collect an enormous amount of data in a very short period of time and that was our big challenge.

PALCA: I got you. And just finally before I take some calls, and I'd like to invite our listeners to call at 800-989-8255, but my last question is, why do you need to be, I mean, what about this high resolution camera work is gonna help you understand where the water was? Why do you need detailed pictures like that? Isn't it enough to see giant flood plains or something like that?

Dr. MCEWEN: Several things, one is I'm a geologist and I really like to see the rocks and the layers up close to deduce what they mean and what the history is, but what we really need is to get on the ground to understand these things, and before we can get on the ground, we need a safe landing site, and that really is probably the most important thing HiRISE will do would be to certify for sure where the safe landing sites are because we can actually see the rocks that are big enough to kill a lander.

PALCA: So, it'll be useful in two senses, one in scientific and one in picking the right real estate for the next mission.

Dr. MCEWEN: That's correct.

PALCA: Okay, well let's go the phones now and how about, let's see, Michael in Kensington, Maryland. Welcome to SCIENCE FRIDAY. Michael, are you there?

PHIL(ph) (Caller): Hello this is Phil from Burke, South Dakota.

PALCA: Oh, well, I pushed the wrong button then. I'm sorry, but hi, Burke.

PHIL: That's okay. Well, okay, quick question. I've checked the web site and as you mentioned there hasn't been many pictures taken for HiRISE and I'm wondering, are you planning to take any photographs during the next few months during aero-breaking? That's one question. The second question, are you planning to take photographs of the moons of Mars also? And I guess, one more, are you gonna look for the Mars polar lander? So that's my three questions.

PALCA: All right.

Dr. MCEWEN: Okay, yes, yes, and yes. We're going to take images next week, actually before we start aero-breaking, but in the current orbit. It'll be just nine images total and 46 gigabits of data which is a heck of a lot of data to a lot of old missions, but it's a drop in the bucket to MRO. But those will be wonderful to us, but that's it, and we can't take images during aero-breaking until next fall. Now next fall, we do a number of calibrations, one of those especially for CRISM, the imaging spectrometer which is also a fantastic instrument on MRO. They are particularly interested in looking at Deimos, one moon of Mars, for calibration purposes and we hope to get some pictures. May not be great pictures, but because of their requirements, but at other times we will take pictures of the moons. I want to say though that the European Mars Express mission has taken some fantastic missions of the Martian moons and they are in an elliptical orbit where they get close to those moons so they can actually do better than we can. Now Mars Polar Lander, yes, we will definitely be looking for that...

JOE PALCA, host: And remind us which was, that was the mission that didn't land as softly as people had hoped?

Dr. McEWEN: The Mars Express mission was both an orbiter and the Beagle Two Lander, the Beagle Two Lander was never heard from, and so that's another one along with Mars Polar Lander that we will be looking for, because this is important for engineering, the engineers are very anxious to understand what was the failure mechanism, and if we can see that the parachute deployed or we can see that it, one of these landed and opened their solar panels, or if they crashed, all that is very important information for assessing what happened and avoiding such mistakes in the future.

PALCA: Okay. Thanks very much for that question.

PHIL: Thank you.

PALCA: Okay. What about the Rovers? Has the Mars Recognizance Orbiter got enough resolution to pick out the Rover or its landing site?

Dr. McEWEN: Yes, we will see the Mars Rovers very nicely and we'll also see the train around the Rovers, that will be a big help to them in terms of putting their observations in the more regional context and it may also influence their decisions about where to go next and keep exploring assuming they're still alive and going at that time.

PALCA: Okay, let's take another call now, and I think I've got Gerald in Montana. Gerald, are you there?

GERALD (Caller): Hello? Yes.

PALCA: Hi, welcome to the program, what's your question?

GERALD: Well, thank you very much. This is all wonderful technology that we have going on and be able to see it first hand it's just absolutely amazing and what I was wondering is what is the long-term goal for all of these projects? Is it just simply to understand the geology and the history of the formation of Mars or is the beginning projects for future colonization?

PALCA: Oh, colonization...

GERALD: And I'll take my answer off the air. Thank you.

PALCA: Okay, thank you. What about that, Dr. McEwen?

Dr. McEWEN: Well, I'd say it's both depending on who you talk to. Certainly scientifically Mars is of great interest in particular in the search for life, either ancient life or current life, and we have one example of life right now, a second example would be of extreme importance to understanding the origin and evolution of life, and the opportunities for life then beyond Mars, beyond this solar system even. And that's key to the follow the water strategy, we need to find where the water is or was in order to know where to look for life.

There's also a long-term goal for human exploration of Mars. It doesn't look like that's going to happen any time soon, but it remains of interest, and again, you want to find out where the water was, because you need water to create oxygen to breathe and to create fuel, so water is probably the most valuable resource on Mars for any future human colonization.

PALCA: Okay, well Dr. McEwen I'm afraid we've run out of time. So thank you very much and thanks for joining us today.

Dr. McEWEN: Okay, thank you.

PALCA: Alfred McEwen is a Professor of Planetary Geology in the Lunar and Planetary Laboratory at the University of Arizona in Tucson. He's also the Principal Investigator for the High Resolution Imaging Science Experiment. When we come back, changing gears to look at something a bit closer to home, mad cow disease in the United States. Stick around. This is TALK OF THE NATION from NPR News.

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