IRA FLATOW, host:
This is TALK OF THE NATION: SCIENCE FRIDAY. I'm Ira Flatow.
A little bit later, we'll take you on safari. But first, a nearby asteroid is whizzing toward Mars. New data shows that the space rock has a 1-in-25 chance of hitting the red planet, and if it does it will unleash the equivalent of 300 million sticks of dynamite, researchers say. Astronomers are keeping their fingers crossed, hoping for this cosmic collision. Why?
Here to talk about it is Donald Yeomans, manager of the Near-Earth Object program at NASA's JPL in Pasadena, California. He joins us by phone. Welcome back to the program, Dr. Yeomans.
Dr. DONALD YEOMANS (Manager, Near-Earth Object Office, National Aeronautics and Space Administration Jet Propulsion Laboratory): Well, thanks very much, Ira.
FLATOW: What's the chance now of getting hit?
Dr. YEOMANS: Well, we got some additional data that came in from the Sloan Digital Sky Survey, and we used that to update the orbit and predictions. So it's now gone from 1-in-75 chance to 1-in-25 chance.
FLATOW: Wow. Could it actually get even greater?
Dr. YEOMANS: It could, but the most likely scenario is that additional data will drop it to zero. But we don't know that and won't until we get additional data, of course.
FLATOW: Now, what's so good about it hitting Mars?
Dr. YEOMANS: Well, it would be a scientific bonanza. The asteroid, should it hit, would dig out a hole better part of a half mile in diameter and several hundred meters thick or deep. And so the Mars orbiting spacecraft, three of them, could get a great look at some of the sub-surface layers of Mars.
FLATOW: Of course, there's always a chance you could hit one of the Mars rovers.
Dr. YEOMANS: Not much of a chance, but the impact path…
Dr. YEOMANS: …and it's a path across the surface of Mars, should it hit, does pass just above the Opportunity rover.
FLATOW: So you're not worried about that.
Dr. YEOMANS: No. No.
FLATOW: And so if you have this big impact, what do you learn from it?
Dr. YEOMANS: Well, it's sort of like a deep impact that we had with the comet a couple of years ago, except that Mother Nature's providing the impact or the circumstances of the impact and how the planet reacts to the impact will tell us a lot about how the planet is put together and what is the subsurface layers and materials that are there. And so it's a nice free impact and it would give us a bonanza of scientific information.
FLATOW: The fact that there's really not very much atmosphere on Mars keeps it from burning up. Would that be the same effect here on Earth if we got hit by it?
Dr. YEOMANS: Well, of course, the Earth's atmosphere is much thicker, so an object of this size - and it's about 50 meters in size - might not make it to the Earth's surface whereas on Mars because the atmosphere is so much thinner it would punch right through and smack the surface.
FLATOW: What is the projected date of the impact?
Dr. YEOMANS: Well, if it does hit, it would be January 30th about 10:55 Greenwich Time.
FLATOW: 1-800-989-8255 is our number. We are talking with Donald Yeomans about the possible 1 - now, 1-in-25 impact shot that this is having, might have, right? 1-in-25?
Dr. YEOMANS: Yup.
FLATOW: And when will you refine this? You said you had a 1-in-75, now 1-in-25, well, we - should we hold our breath for another refinement?
Dr. YEOMANS: Well, we are going to get additional data as soon as the object gets away from the moon. It's very faint and it's currently right near the moon. So in another week or so it will move away, and we're hoping that some of the larger telescopes will get additional data to allow us to refine the predictions and see whether or not there's still an impact possibility.
FLATOW: Tell us a little bit about how it was tracked, how it was found and how you know where it's going.
Dr. YEOMANS: Well, it was found by the Catalina Sky Survey folks in near Tucson, Arizona, on November 30th, and the Magdalena Ridge folks in New Mexico provided additional data as did the Space Watch folks, again, near Tucson. And then, more recently, we had what we call pre-discovery observations coming from the Sloan Digital Sky Survey folks. Andy Puckett checked in and provided some data on November 8th, 12 days prior to the actual discovery.
So these were observations that were sitting in the archives that - until he pulled them out. We didn't realize they were of this object. So now, we have a fairly extensive list of observations covering the time from November 8th through December 19th on which to fit a trajectory. So we try an initial trajectory, see if it fits the data. If it doesn't, we adjust the initial conditions until it does, sort of - we call it a weighted least squares differential correction, but it's just adjusting the initial conditions until you can match those observations. And then once you've done it…
Dr. YEOMANS: …you can run the orbit forward with all the planetary perturbations on the computer and see where it'll be.
FLATOW: Hmm. Is this part of this whole near-Earth object tracking system that you have set up?
Dr. YEOMANS: It is. It's very much part of that. Normally, we deal with objects that are getting close to the Earth, of course. But our software doesn't discriminate against the other planets as well, and although we don't usually publish that data, we do monitor the approach of asteroids near the other planets as well.
FLATOW: And you can - you have a resolution that you can see something as small as 50 meters, it sounds like.
Dr. YEOMANS: Well, yeah. When I - it was discovered when it was fairly close to the Earth just a few tenths of an astronomical unit, and by a fairly large telescope, a 1.5 meter telescope aperture. And it's getting fainter, so we're going to need even larger telescopes in January to see this object.
FLATOW: Mm-hmm. So if this had been closer, or as close, and was headed toward the Earth hypothetically - it isn't - but if it had been - would we have enough, you know, how far away would we have known about it? How many days, hours, whatever?
Dr. YEOMANS: Well, that would depend on whether the four NASA-supported surveys were actually looking in that direction at the right time. But these objects, as you pointed out, are fairly small and hard to find. And the current goal of the NASA survey is just to find the big ones, which do the most damage of course. But it's hard to say. Hopefully, we would have picked this up several weeks in advance of any close encounter.
FLATOW: Let's see if I can get a phone call or two. And 1-800-989-8255 is our number.
Let's go to Alex(ph) in Coral Springs, Florida. Hi, Alex.
ALEX (Caller): Hey. How are you?
FLATOW: Hi, there.
ALEX: I had a question. Number one, how - if I have a telescope at home, how could I track this object? And number two, is there any chance about hitting Earth or any of the particles that it's going make once it hit Mars?
FLATOW: Okay. Good question.
Dr. YEOMANS: Okay. Well, unless you have a very large telescope - this is really out of the question for seeing with an amateur telescope unless it's, you know, several meters in diameter and there's - I don't know of any of those. So this is really for the pros. We're hoping that some of the folks in Hawaii on top of Mauna Kea with the 6.5-meter telescope - it's as but 24th - it will be 24th magnitude, which is well beyond amateur telescopes.
And your second question is this object poses no threat to Earth even if the eject - even if it does hit Mars and digs the crater and throws the eject up in the atmosphere, only the finest dust, micron size dust, would escape and that's absolutely no threat to anyone.
FLATOW: Well, Dr. Yeomans, I want to thank you for taking time to be with us. Fascinating stuff. We'll be watching.
Dr. YEOMANS: Okay.
FLATOW: Donald Yeomans is manager of the Near-Earth Object program at the NASA Jet Propulsion Laboratory in Pasadena, California.
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