Planetary Radio: Space Exploration, Astronomy and Science - A Near Miss for Mars and Bill Nye Pays Tribute to Mercury!

Episode Date: January 14, 2008

A Near Miss for Mars and Bill Nye Pays Tribute to Mercury!Learn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

A near miss for Mars, and Bill Nye returns this week on Planetary Radio. Hi everyone, welcome to Public Radio's travel show that takes you to the final frontier. I'm Matt Kaplan, and we are jam-packed this week. You've probably heard Don Yeomans quoted in the last few days. Don heads NASA's Near Earth Object Program and it's his office that has been tracking the course of

a 50 meter rock that won't be going splat on the red planet. He'll join us in a couple of minutes. Emily will also sound off about that Near Mars object in her Q&A segment and Bruce Betts will bounce in to tell us what's up and what's going down with the latest space trivia contest. Wow, we barely have time to tell you that Shuttle Atlantis is now targeting February 7 for its next liftoff. By the time you hear this, humankind should have returned to the planet Mercury.

That's reason enough for Bill Nye to celebrate. I'll be right back with Don Yeomans. Hey, hey, Bill Nye the Planetary Guy here. I'm the science guy and, of course, vice president of the Planetary Society. And this is another historic week in space exploration. We are sending the Messenger spacecraft very, very near the planet Mercury. Now, I remember, or if I may, I remember when I was told that Mercury goes around the sun very fast compared to other planets, only 88 Earth days, which is appropriate.

The messenger of the gods, Mercury, had wings on his sandals, for crying out loud. And I remember being charmed that, like the moon, I was told, Mercury spun just once for every orbit of the sun. Well, that turns out not to be true. It was a big discovery with radar that Mercury spins two-thirds of a time when it goes around the sun. Wait, that turned out not to be true. We discovered back in 1974, the beginning of the disco era,

almost 34 years ago with the Mariner 10 spacecraft, that Mercury spins about half a turn for every orbit of the disco era, almost 34 years ago with the Mariner 10 spacecraft, that Mercury spins about half a turn for every orbit of the Sun. That is quite an enchanting thing. But despite that, Mercury is crazy cold on one side and very hot on the other. It's about 470 Celsius on the hot side. It's not hot enough to melt lead. It's not as hot at Venus because the Mercurians, if there are any, don't have any atmosphere. And on the cold side, it's about 170 Celsius below zero, colder than dry ice. Oh, not quite as cold as liquid nitrogen, but it's getting down there at any rate. Get it? The Messenger spacecraft will have just flown by on the 14th of January, and we will discover things that have never been discovered before.

You know, it is not beyond beyonding that with these cold conditions on Mercury, you know, it hardly wobbles at all. The Earth has seasons because it's tilted. Not so Mercury. It could be that these craters near the north and south pole of Mercury hold ice, water ice. If we discover water ice on another world, my friends, it will change ours. And the cost of this mission is less than a cup of coffee per taxpayer. People say, why are you sending this mission to Mercury?

What are you going to find there? We don't know. That's why we're going. And it benefits everyone on Earth. Oh, my friends, it's an exciting week when it comes to Mercury. Talk to you next time on Planetary Radio. For now, I got to fly. Bill Nye, the Planetary Guy. It's Don Yeoman's job to make sure nothing like the rock that wiped out the dinosaurs goes unnoticed by humankind. The senior research scientist at the Jet Propulsion Lab heads NASA's NEO, or Near Earth Object Program Office,

where they currently have tallied more than 5,000 comets and asteroids that cross our home planet's path. Over 700 of these are more than a kilometer wide. The latest such object to cause a stir is asteroid 2007 WD-5. It missed Earth, but looked for a while like it might make a big new hole in Mars. I visited JPL just a few days ago to talk with Don about this and other NEOs. Don, thanks very much for joining us on Planetary Radio. We are talking and speaking really just hours after the latest observations of this object.

And I guess the result is that the Martians have reason to breathe a sigh of relief. Yeah, they do, I'm afraid. We were actually rooting for the asteroid. It was discovered on November 20th, just around Christmas time. The impact probability with Mars actually peaked around 5%, 1 in 20 chance of actually hitting Mars at one point.

And those are pretty good odds, right? I mean, we don't see them get, we haven't seen them get too far beyond that. And if they ever do get further beyond that, we'll hope it's Mars and not Earth. Yeah, that's the point. You would expect an object of this size, which about 50 meters, about half the size of a football field, you'd expect something of that size to hit the Earth and Mars about every thousand years. So this was a long, long shot, but one that we were actually pretty excited about. And excited because we've got lots of theory about what happens when a rock this size hits a planet, but we don't get to see it happen very often.

Well, that's true, and it was happening to Mars and not us, of course, so it was doubly exciting. I was wondering about this last night as I was looking at your website, the NASA NEO program website, which we'll provide a link to, of course. Would part of that be that we'd be looking at this, a really fresh crater where so many of them are ancient? Yeah, that's the point. We would perhaps have a chance to observe the crater being formed, and that would tell us a great deal about what the surface and subsurface of Mars is about. And then we'd have a chance to look down into the crater being formed, and that would tell us a great deal about what the surface and subsurface of Mars is about. And then we'd have a chance to look down into the crater. Even during the crater formation itself, folks on Earth with a modest-sized telescope could

have seen the flash, possibly could have seen the dust rising up into the tenuous Martian atmosphere. So there was all kinds of interesting things that could have played out. So there was all kinds of interesting things that could have played out. There are certainly estimates of just how big a hole in the red planet this would have made. Well, that's true. We estimate that there was about 50 meters in size, and given the velocity with which it would hit and the fact that Mars' atmosphere wouldn't put up much of a fight, the crater itself would probably be on the order of a half to one kilometer in extent

and several hundred meters deep. So it would have been quite an explosive event. Pretty impressive. I mean, from 50 meters. I mean, what if this thing had been a kilometer? A kilometer would have been an extraordinary event, but you wouldn't expect that to happen nearly as often because there's so many fewer of those guys. Thank heavens. Yeah. You mentioned earlier the fact that the probability of an encounter with Mars actually rose before it started to fall again, which I guess is typical. It is typical.

It's a little hard to understand at first. The uncertainty region, we have a preferred region for where we think the asteroid is at any given time, but there's an uncertainty region on either side where it could be. So we don't know exactly where the object is until we have an orbit that's very secure. So when we first discover the object, the orbit is not so secure, and so we have a cigar-shaped region in space where the asteroid could be, and the center of that cigar is the nominal or most likely position. So what we have to do is we have to run that cigar-shaped uncertainty ellipse into the surface of Mars

and ask the question, how much of that cigar-shaped ellipse is taken up by the surface of Mars itself? cigar-shaped ellipse is taken up by the surface of Mars itself. So initially, when the cigar is huge, Mars just takes up a little bit of it because the uncertainty region is so large. And so the impact probability is fairly small. And then as we get more and more information, data on the asteroid, the orbit gets better. The uncertainty region, the cigar, shrinks a little bit.

And if it's still sitting on, a part of it is still intersecting Mars, then the impact probability actually rises. But as soon as we get enough data to secure the orbit to make it quite accurate, then the uncertainty region shrinks yet again. And as soon as it drops off the surface of Mars, then it drops to zero like a stone. So you get this situation where you have a low impact probability, it rises and peaks, and then it drops to zero, assuming it misses, of course. If it doesn't miss, of course, it keeps going.

But we haven't seen one of those yet, except for Shoemaker-Levy 9, the comet that ran into Jupiter back in 1994. Yeah, which resulted in some pretty good science and some terrific images. It did indeed. And, in fact, that was the incident that created the need for our software. We were asked to provide predictions of where those chunks of the comet would land. And so Paul Chodas and I developed the software that would predict where these things would land and what time they would land and compute the impact probabilities.

And so that software developed into what we're now using for all near-Earth objects. Watching those probabilities fall and rise and fall again obviously is totally dependent on the data you gather, which is totally dependent on people data you gather, which is totally dependent on people around the world making observations. And I was really interested to see on your website again, the different telescopes, the different facilities that were observing this object. Yeah, it was great. The community really pulled together and helped us out a great deal. It was discovered, of course, by the Catalina Sky Survey near Tucson. It was quickly

observed by Magdalena Ridge in New Mexico and also by Spacewatch, also near Tucson. But we had observations from Colorado in Spain. We had observations, again, from Magdalena Ridge. And we also had what we call pre-discovery observations. One enterprising gentleman, Andy Puckett, who's in Alaska, actually went back into this digital Sloan survey data and pulled out pre-discovery observations that were made on November 8th. There it was, but nobody realized when that survey image was taken that they were looking at this object. That's right. This fellow you mentioned, Andy Puckett, a professional astronomer, amateur astronomer? A recent PhD in astronomy, not in orbit determination, but he actually heard the story of this asteroid that might hit Mars on the TV.

He took the initiative to say, oh, hey, let's integrate the orbit back in time on our website, which you can do. And then he asked the question, where was it prior to his discovery and said, hey. You got into this business, at least you became head of the program about 10 years ago. That's right. A lot has happened since then. We found a lot of rocks. Yeah, we have. Things really got off the ground in 1998 when NASA committed to the search for near-Earth objects. And we currently have four programs full-time looking for these objects, Kelly and the Sky Survey, the Space Watch group, the Linear group run out of Lincoln Lab at MIT, and LONIOS, the

group at Lowell Observatory. That's Don Yeomans, manager of NASA's Near Earth Object Program Office. He'll rejoin us in a minute. This is Planetary Radio. Hey, hey, Bill Nye the Science Guy here. I hope you're enjoying Planetary Radio. We put a lot of work into this show and all our other great Planetary Society projects.

I've been a member since the disco era. Now I'm the Society's Vice President. And you may well ask, why do we go to all this trouble? Simple. We believe in the PB&J, the passion, beauty, and joy of space exploration. You probably do too, or you wouldn't be listening. Of course, you can do more than just listen. You can become part of the action, helping us fly solar sails,

discover new planets, and search for extraterrestrial intelligence and life elsewhere in the universe. Here's how to find out more. You can learn more about the Planetary Society at our website, planetary.org slash radio, or by calling 1-800-9-WORLDS. Planetary Radio listeners who aren't yet members can join and receive a Planetary Radio t-shirt. Members receive the internationally acclaimed Planetary Report magazine. That's planetary.org slash radio. The Planetary Society, exploring new worlds. Welcome back to Planetary Radio. I'm Matt Kaplan. My guest is JPL's Don Yeomans, manager of NASA's Near-Earth Object

Program Office. I asked Don how the search for the biggest of these asteroids and comets is going. I asked Don how the search for the biggest of these asteroids and comets is going. NASA's current focus is to try and find 90% of those objects that are one kilometer and larger by the end of this calendar year. And we're close to that. I'm not sure we'll make the 90% mark, but we're certainly going to be in the upper 80s. The rationale was that these are the objects that if they hit would cause a global disaster. You know, it was a 10-kilometer-sized object that took out the dinosaurs 65 million years ago. But anything over a kilometer is going to cause a global problem. And so find those first.

And there's only thought to be about 900 of those objects. So it was a doable thing. And now we're trying to get NASA to sign up for an extended search to find those objects 140 meters and larger within 10, 20, 30 years. Do we have any idea how many of those there are and what percentage have already been found? Well, we have a reasonable estimate of how many there are, certainly about 75,000 of them. So it's an order of magnitude larger than the larger ones that we're looking for now. And I think we found only 4% of them. And that was inadvertent because we're looking for the large ones. But, of course, if a small one gets close to the Earth, it's fairly bright and it is discovered.

But we're going to need larger telescopes to find 90% of the 140-meter-sized objects. Hopefully, NASA will sign up to that before too long. With the current state of observations, the funding, the facilities, telescopes that are available, and the people who are watching, what's the least amount of warning we might plausibly get before, let's say, a 100 or a 150-meter asteroid would impact the Earth? Well, I noted that these four observatories are looking every clear night, so it's unlikely that something of that size would sneak up on us and take us by surprise. up on us and take us by surprise. What is not unlikely, however, is that something like that could be discovered, you know, a month or two prior to an actual collision. So that would be a problem. And so you'd have to, you couldn't mitigate by trying to push it off or slow it down in space. You'd have to try and evacuate the area that might be affected. And certainly that's the ultimate goal, I guess.

As some people are talking about, Rusty Schweikert with his B612 Foundation, who's talked about this on the show, is to get to the point where not only can we find these early enough, but we figure out how to nudge them out of the way. Yeah, yeah, Rusty's been one of the key figures in trying to draw attention to the fact that we really don't have any solid plans in place now for mitigation. And should a 50-meter or 100-meter-sized object be found to be on an Earth-impacting trajectory, there are no definite plans to deal with it. That being said, there have been some studies, and the National Research Council has been directed by Congress to look into this issue again and to recommend strategies for dealing with the various sizes and the various threat levels that may occur. So I think that process has been started. We haven't started demonstrating mitigation techniques or anything, but at least

the paper studies are underway and people are starting to think of just what makes sense. Is it nuclear weapons? Is it gravity tractors? Are you talking about throwing rocks off the surface and generating a thrust that way? So there's a number of technologies that we have currently that could be used to deflect an asteroid. We ran into a comet in July of 2005, demonstrating that we have the technology to run into these things. And these so-called kinetic impactors could be used to slow down some of the smaller asteroids that represent a threat to Earth. So we do have the technology to deal with these objects.

We just don't have a matrix or a plan to put in place such and such technology given such and such a threat. That intentional impact, of course, deep impact for which you were a co-investigator. Of course, the idea here is not just that we need to watch out for these comets and rocks in space, but that they are interesting objects in themselves and worthy of study. And I know you're on the science team for Hayabusa. You're hoping to get your hands on a little bit of asteroid material, if all goes well. Yeah, that's a good point.

It's not sufficient just to point out the bad press that these comets and asteroids gets from time to time. It's kind of like sharks. Yeah, but unlike sharks, these objects are probably responsible for our being here in the first place. They may have delivered to the early Earth much of the water and carbon-based materials that allowed life to form. They may have struck the Earth after life formed, punctuating evolution and allowing only the most adaptable species, that's us, to develop further.

So we could possibly owe our place on the food chain to comets and asteroids that have impacted the Earth. And in the future, these objects could be the resources for building interplanetary habitats. You're not going to build habitats on the Earth and launch them into space. You're going to go up there and look around for raw materials to build your structures. Asteroids can provide that. You're going to look around for water to sustain life. You could break the water down into hydrogen and oxygen, which is rocket fuel. So at some point, the asteroids could

provide the structures for developing life in interplanetary space, and the comets could be the fielding stations and watering holes for future interplanetary space, and the comets could be the fielding stations and watering holes for future interplanetary development. Don, thank you very much for keeping an eye out for all of us. My pleasure. Don Yeomans is a senior research scientist at the Jet Propulsion Lab near Pasadena, California. As we said, co-investigator for that deep impact mission, our first movie-worthy title

for a mission to an asteroid, and a member of the science team for Hayabusa. Most significantly here, he is the manager for NASA of the NEO Program Office, located at JPL. We're going to move down the block to pick up with Bruce Betts for this week's edition of What's Up, but that will be after a Q&A visit with Emily. Hi, I'm Emily Lakdawalla with questions and answers. A listener asked, will any of the spacecraft at Mars watch that asteroid pass by? An asteroid on course for Earth would generate alarm around the world, but an asteroid on course for Mars had Mars scientists thrilled with anticipation. They imagined watching an impact

happen, measuring how the dust it tossed into the air floated around the planet, and studying the resulting crater. It'd be an unprecedented opportunity to understand a fundamental process that shaped the surface of Mars and all the other terrestrial planets. But now that an impact has been ruled out, there's little reason for the Mars spacecraft to tear themselves away from their work to watch 2007 WD-5 pass by. Because WD-5 is small and faint, and because its orbit is still somewhat uncertain, it presents a real observing challenge. For instance, it'll be too faint for the rovers to spot even if they were to warm themselves up for energy-costly nighttime operations. Also, on its approach to Mars, WD-5 will be coming in from the direction of the Sun, and the orbiters can't safely point that way.

They'd have to wait until the asteroid passed by and watch it on its way out. And even though the HiRISE camera on Mars Reconnaissance Orbiter could, in theory, resolve the tiny body and take a photo showing features on its surface, WD-5's position is still too uncertain for HiRISE to be able to point precisely enough to find it. The best chance was the wider-angle cameras on the orbiters, but without an impact to look forward to, it just doesn't seem worth interrupting their Mars observations, especially when large telescopes on Earth can track the asteroid just fine without help from Mars.

Got a question about the universe? Send it to us at planetaryradio at planetary.org. And now here's Matt with more Planetary Radio. Well, as promised, it's time for What's Up with Dr. Bruce Betts, the Director of Projects for the Planetary Society. He's going to tell us all about the night sky. And I'm going to tell him about the stuff I got at the JPL store. Cool.

What's in the bag? What's in the bag? There's a new store right in the visitor's entrance. I got there early. And so here's the bag. And I bought myself, look, I bought a JPL t-shirt, right? Nice. And I got you a present.

Here it is. Check it out. Check it out. It's the official Saturn V Superball. That's exactly right. Superball, you know, a couple inches in diameter with clear on one side with a little Saturn V in there. Thank you. The Saturn V is a little misshapen. It is in a Super Bowl.

Yeah, it is. And it really bounces well, too. Cool. All right. Well, bounce us on up into the night sky. I will bounce us to the night sky. Let's talk about Mercury, because I'm just so excited about this Mercury flyby coming up.

And Mercury is also going to be Mercury flyby by Messenger, of course. You can listen to last week's show for more on that i'm going back there i'm going to be back there at apl when they it's going to be cool you're very fortunate mercury you'll be able to see it uh it gets better over the next week or two so depending on when you're listening to this it's very low in the glow of sunset so look for just above the west or west-southwest horizon about a half hour after sundown. And it's a pretty bright object. It's magnitude minus one for those who play the game. If you look at the same time or any time in the evening, look overhead and you'll see Mars as the bright orangish thing that's getting dimmer over time, but still quite bright and good. And it's

starting to get gibbous if you look at it through a telescope. I love that word. Past opposition where you see a nice full circle, and now it's moving to gibbous, the official term for where you have a little bit of the dark side of Mars visible, but mostly the light part, what we see with the gibbous moon quite frequently. That's Mars. You also have Saturn coming up in the mid-evening right now in the east, looking yellowish and dimmer than the other objects we've been talking

about. Great telescope object as always. And in the pre-dawn, you've got Venus, brightest star-like object over there in the east. And Jupiter's making its way up. You might catch it low in the east, but wait two or three weeks and then it'll uh it'll really get up there and be a another nice bright object beneath venus in fact i want to start mentioning uh february 1st conjunction of venus and jupiter they're going to snuggle up only 0.6 degrees apart in the pre-dawn sky two really bright planets wow two brightest planets very Very close. And February 7th, coming up on an annular solar eclipse. So for those of you in Antarctica, you might see it as annular. But a partial eclipse will be visible throughout New Zealand and some parts of eastern Australia. And I know we've got a good number of listeners there as well as a few in Antarctica.

Or maybe one. Now and then. Yeah, we have one or two. We'll move on to this week in space history. Write to us if you're in Antarctica, by the way, and you see this. Or even if you don't. Yeah. This week in space history, it was three years ago,

Huygens landed on Titan during this week. You can still hear the sounds on our website of the descending through the atmosphere. I've mastered approximating them, by the way. Oh, would you do it? Not that we have a lot of time. All right, well, 10 seconds. Here is the entire, like, two-and-a-half-hour descent compressed to 10 seconds. Okay.

And this is what it sounded like going through the atmosphere. Did you catch the landing there? Yeah. I love the modulation there. Yeah. That was wonderful. Thank you. Yeah, you can check it out on the website, but it's going to sound very similar to that.

So there's really no point. Really, there isn't. You've heard it. You've been there. But it is cool to hear something sound from a billion miles away. It is. Or me. sound from a billion miles away it is or me uh 2006 two years ago new horizons was launched headed off pluto past jupiter about a year later off to pluto in 2015 1969 first docking of two

manned spacecraft we're gonna come back to that in the trivia question on to random space fact On to random space fact. Near-Earth asteroids, as you've just been talking about with our guest, are divided into groups. Atons, Apollos, and Amores. Amores? Amores. Would that be Amore if we were in Italy? Amore. Well, they're named after the first asteroids or asteroids of those classes that were discovered.

Aten's are Earth-crossing near-Earth asteroids with a semi-major axis smaller than the Earth's. And Apollo's are Earth-crossing with semi-major axes larger than the Earth's. And Amore's are Earth-approaching near-Earth asteroids with orbits exterior to Earth Earth but interior to Mars. There you go. That's the educational portion of our program.

There we go. On to no more education with the trivia contest. Oh, there may be a little bit more. We asked you about Phoenix. One instrument on the Phoenix lander headed to Mars are copies of ones that flew on Mars' polar lander. How did we do? I'm going to rush through this because we're running out of time, but I will tell you,

our winner got all four. At least as far as we can tell, there were four. Margaret Schwartz, Baltimore, Maryland, and you confirm these. Rack, the robotic arm camera. Yes. SSI, surface stereo imager.

That's right. TIGA, thermal and evolved gas analyzer. Sure thing. And Marty, the Mars descent imager. Sure thing. And MARDI, the Mars Descent Imager. Indeed. All based, at least, on the instruments that flew on Mars Polar Lander. And Margaret's going to get a year in space calendar. Fabulous.

Beautiful year in space calendar. Now, speaking of year in space, we return to our anniversary. Where are we with prizes here these days? I don't know. It's up to you. We could do another calendar, I think. One more. Yeah, right.

The Year in Space calendar, because they're so cool, and can actually be found on our website as well. What were the first two-man spacecraft to dock in space? I know, you probably couldn't see that coming. That is the correct year, contestant, but that is not the answer to the question. That is the correct year, contestant, but that is not the answer to the question. Go to planetary.org slash radio to find out how to get us your answer and compete for the beautiful year in the space calendar. You got till the 21st. That would be Monday at 2 p.m. Pacific time on the 21st of January in this year, 2008.

We're done. All right, everybody, go out there, look up at the night sky, and think about fizzy bubbles. Thank you, and good night. He's Bruce Betts, the Director of Projects for the Planetary Society. He joins us every week here for What's Up. Planetary Radio is

produced by the Planetary Society in Pasadena, California. Have a great week. Редактор субтитров А.Семкин Корректор А.Егорова