Planetary Radio: Space Exploration, Astronomy and Science - Water: Now It Has Been Found on an Asteroid!

Episode Date: September 6, 2010

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Music Music Music Music Music Music Music Music Music Music Music Music, Music, Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, and Music, I'm Matt Kaplan of the Planetary Society. Andrew Rivkin leads one of two teams that has found water ice coating an asteroid. Could this be a clue to the mystery of water on Earth? We'll talk with him about that and other questions. Any water on scorching Venus is definitely not ice. Bill Nye will take us there in his commentary for this week. And we'll once again find Bruce Betts collecting planets for his What's Up report that includes a milestone for Trekkies and another

chance for you to win a copy of Packing for Mars, Mary Roach's hilarious yet informative and inspiring book about human space travel. We'll begin as always by checking out recent highlights of the Planetary Society blog with Science and Technology Coordinator, Emily Lakdawalla. Emily, I have to start with the best image ever of the Great Red Spot. It is just so beautiful. I just want to lose myself in it. It's amazing how you see worlds at every scale.

You zoom in and you see all kinds of little stormlets, and then you zoom back out and you see the Great Red Spot, and I should add one of the big white spots that was wandering around south of the Red Spot when Voyager flew past. Yet again, here's an image from Voyager more than 30 years old. Why are we seeing it now? Well, of course, we saw some versions of this image from Voyager, or at least some people did shortly after Voyager flew past. I was a little young to notice these things. But, you know, it takes modern computing power to really bring out the fantastic detail that's visible in these photos. It's a three by four footprint photo. That means that Voyager had to reposition its camera the total of 11 times during

the shoot, and it shot the image through two different filters. And in the past, you know, back in the 70s, computers just weren't up to the task of reprojecting and assembling all of these data. And now there are amateurs going back through the old data and doing some absolutely incredible work. And because Cassini didn't get closer to Jupiter than Voyager did, its photos aren't any more detailed. And because of Galileo's antenna problems, it didn't get any particularly detailed photos of Jupiter's atmosphere.

So Voyager is really it. Well, a tip of the planetary radio space helmet to Bjorn Johnson. I hope I got his name right. And let's move on to work by yet another talented person out at Iapetus, even farther out in the solar system. That's right. But this one actually gets paid to do what he does. It's Paul Schenck. And he is really a master of outer planet satellite topography. That's his research niche. And

he's produced some spectacular flyover videos of some of the icy moons out of the outer solar system. And my favorite one is this view over the equatorial ridge of Iapetus. It's really beautiful. It actually mirrors a perspective that Cassini had. You know, Cassini flew over the equatorial ridge. So the photos, they may seem like they're computer generated, but they really are taking the data that Cassini shot through its camera and just kind of adding a little bit in between and making a topographic model to really help us appreciate the topography of Iapetus as seen from Cassini. And it's not hard to imagine flying over, oh, the Alps or the Andes on Earth. No, not at all, except this is really, really dark and dirty. It's a strange satellite.

It's totally covered with this black, dusty material, except for the weird snowy spots that are on these mountains. It's kind of crazy. Last quick mention, something I will mention with some self-consciousness, Last quick mention, something I will mention with some self-consciousness, and that is the just-posted video from the Planetary Society open house a few weeks ago, which features, among other people, you getting to meet, I guess, a hero? That's right. I'd never met Buzz Aldrin in person before, so that was a great pleasure.

And it was really a fun, actually, not just meeting the luminaries like Buzz Aldrin and Bob Picardo and Bill Nye, of course, but also meeting all of the members and well-wishers who turned out for the event. It's all there on the blog at planetary.org. Just look for Emily's picture up at the top left on the homepage, and you'll get to enjoy all this stuff as well. Emily, thanks again. Thank you, Matt. Emily Lakdawalla is the Science and Technology Coordinator for the Planetary Society and a contributing editor to Sky and Telescope magazine.

You know what? We're not done with the blog. Here's Bill. Hey, hey, Bill Nye the Planetary Guy here, soon to be Executive Director of the Planetary Society. But we'll get to that in a minute. First of all, I was in Madison, Wisconsin in the United States this week for VEXAG, the Venus Exploration Advisory Group meeting. These are scientists from all over the world who have taken an interest, if I may, a deep interest in the planet Venus. They agree on what software they're going to use to communicate with the Deep Space Network and to communicate with the Venus Express, a European space agency craft that's orbiting Venus. The Japanese Aerospace Exploration Agency has got a mission that's on its way,

has this super clever orbit where they're going to see Venus in bright sun and at night, and they're going to look at the atmosphere edge on all with one orbit. It's a beautiful thing. And I'll tell you what, the reason people are exploring Venus is because it is shrouded in clouds, and if I may, shrouded in mystery. You know, these are scientists who look at their species of sulfur-bearing compounds. They look at their deuterium, the extra neutron that might be in the occasional hydrogen atom, and they don't know, they can't agree on whether or not there are volcanoes on a planet. That's just the next one over. I mean, as space explorers, we can tell you that there's a huge volcano on Mars, volcanoes on a moon of Jupiter. There's crazy mountains on

moons of Saturn. And yet people don't know whether or not there's a volcano erupting right now on the next planet over, our sister planet. And every one of these people, as he or she finishes his or her talk, they got a little reference to climate change. Venus is the worst case of a greenhouse effect runaway where the acid clouds rain sulfuric acid and the surface is so hot the acid doesn't reach the ground. It is a hellish place. And if climate change continues on Earth the way people believe it might, we are in for trouble. So by studying Venus, we might learn a great deal about the Earth. And get this, my friends, by the time you hear this, I will be executive director of the Planetary Society. I've written about both things. I've written about VEX be executive director of the Planetary Society. I've written about both

things. I've written about VEXAG and taking over the Planetary Society on our website, planetary.org. But for now, I got to fly. Bill Nye the Planetary Guy. Where did Earth get its bountiful supply of water? Many scientists think our planet wasn't always so blessed. Were we bombarded by millions of those dirty snowballs called comets? Yes, there's little doubt that this has been one source of H2O, but there are problems with that theory, as you'll hear from Andrew Rivkin. And he specializes in observing and analyzing the compositions of asteroids at the Johns Hopkins University Applied Physics Lab. His team spent years carefully observing a

space rock called 24 Themis. Yes, I said Themis, which may be confusing to those of you who heard last week's conversation with Phil Christensen. Phil's Themis is the thermal mapping instrument on the Mars Odyssey orbiter. It's just a coincidence that Andy's Themis has the same name. In fact, Andy wasn't even sure how to pronounce the word. Is it Themis or is it Femis? And I still don't know which one it really is, but I seem to have settled on Themis for better or worse.

Possibly because of the instrument. Possibly because of that Mars instrument, for all I know. We'll have to tell Phil that he's had influence out to the asteroid belt. That's right. However you want to pronounce it, it was last April that Andy's group and an independent team led by Umberto Campins at the University of Central Florida jointly announced that 24 Themis is coated with a thin layer of water ice. That's not all. The scientists also detected the presence of organic molecules, which of course are

the building blocks of life. Andy joined me on the phone from his APL office a few days ago. Andy, congratulations on this first discovery of actual H2O on an asteroid, how much water are we talking about? Well, that's a great question. We're going to need to do some more modeling, and that also you have to make some assumptions about exactly what is going on beneath the very surface there. With the telescope and with the spectrum, we can only see the very surface. So you kind of have to make some assumptions about how representative that is of the whole body. You're probably looking at maybe between 10 and 30 percent water in the interior, if our original assumptions are right. No kidding. I mean, that may not be quite the

level of a comet, but that's a lot of water. It is. It's consistent. We have some meteorites that have fallen to Earth and that we've studied in the lab, and some of those also seem to have about, can have up to 10, 15 percent water in those rocks. In those cases, the water is part of the minerals, so the ice that might have originally been there would have melted and reacted with rock. And in this case for Themis, we think that that probably never happened, so the water just remained as ice as it was originally. probably never happened, so the water just remained as ice as it was originally. The makeup of that water, I guess it's maybe, you can't tell yet, but it may be a little bit different than the water that we've seen in comets? Yeah, from people that have studied comets remotely, you can tell the different isotopes within the water.

And for comets, the evidence suggests that the amount of deuterium, which is a form of hydrogen, the ratio of that deuterium to normal hydrogen is different from what we see here on Earth. And from what we can tell from the meteorites, and we think meteorites tend to come from asteroids, we think that the water in the meteorites is a little bit different from what we see in the comets, closer to what we see here on Earth. Which is a pretty significant find find if this is the case, because this apparently may tell us something about

why our planet seems to have so much of this wet stuff. Yeah, that's right. The models that people do when they try to calculate how the planets formed, a lot of them seem to point to Earth being just too warm to really have started with much water at all. So we think that the water must have been brought in from elsewhere. The easiest way to do that is to have it brought in via impact with comets and asteroids. Since comets are so icy, that was the obvious first place to look.

But since this deuterium to hydrogen ratio isn't what we see here on the Earth, that means that there needs to be some other explanation, or at least that the comets alone can't do it. If the ratio turns out to be correct in the asteroids and in objects like Themis, then that leads to the possibility that a lot of the water instead came from impacts with asteroids instead of impacts with comets. Could you talk a little bit about how this discovery was made? I'm kind of blown away by just how long it took you and another team to independently make this discovery.

Yeah, the observations are, because we're looking for water and we are looking through the Earth's atmosphere, which has water in it, we have to be pretty studious about our calibrations and making sure that we've got all the T's crossed and the I's dotted. We have been interested in water on asteroids for some time. Mostly what we've been finding and expecting to find is water in the form, like I mentioned in the meteorites, where it's bound in the rocks. So we had these lists of objects we were interested in, and in 2003 or so, FEMIS came to be visible and was at the top of our list of objects that we wanted to look at.

We saw FEMIS had this interesting spectral shape, which didn't look like the other objects we'd seen, but because the observations are difficult ones or are tricky ones to make, we didn't necessarily believe it right away. So we had to wait for it to come around a few more times before we had a good combination of good weather and a bright Themis and got the good spectrum we needed to really, really make the fit a really conclusive one for us. And so what you've actually seen is this apparently very thin layer of ice on the surface of Themis?

Yeah, that's correct. The best fit, if you go and try to match it up with spectra that we have in various databases, is only between a tenth and a hundredth of a micron thick on mineral grains, so very thin. And the other types of materials we've looked at to try to see if we could make a better match or even an equivalent match just didn't do the job. Now, I am just about as interested in the other stuff that you found on this big rock, 200-kilometer rock, the organics.

Even though I know it's no surprise, I guess we've seen organics certainly in meteorites, but what does this tell us about the solar system and maybe other things? That's a great question. The organics, we're very excited to find that as well, although we haven't been able to focus quite as much on that. As you said, we know that we've seen organics in meteorites before. But interestingly, even though people have been looking for the organics in asteroids, they've been hard to find. And so people have been trying to come up with reasons why they weren't there or why they weren't seeing them, either suggesting that you couldn't keep them on

the surface of an asteroid because ultraviolet light would break them down or something else like that. But since we see it on the surface of Themis, that suggests that we should be able to see it in other places as well. And I'm sure that plenty of people are now trying to figure out where to point their telescopes to find more of it. And it also does suggest that, again, if we're bringing in, if there's the possibility of bringing in ice and water on asteroids, that you might also bring a significant amount of organic material to the Earth in the same impact. That's Andrew Rivkin,

leader of a group of astronomers that has discovered water on an asteroid. He'll tell us more when Planetary Radio continues in a minute. I'm Robert Picardo. I traveled across the galaxy as the doctor in Star Trek Voyager. Then I joined the Planetary Society to become part of the real adventure of space exploration. The Society fights for missions that unveil the secrets of the solar system. It searches for other intelligences in the universe, and it built the first solar sail. It also shares the wonder through this radio show, its website,

and other exciting projects that reach around the globe. I'm proud to be part of this greatest of all voyages, and I hope you'll consider joining us. 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. Our nearly 100,000 members receive

the internationally acclaimed Planetary Report magazine. That's planetary.org. The Planetary Society, exploring new worlds. Welcome back to Planetary Radio. I'm Matt Kaplan. Water has been found on an asteroid for the first time. This was no mean feat, considering that 24 Themis is orbiting beyond Mars, almost 500,000 kilometers from the Sun. Andrew Rivkin of the Johns Hopkins University Applied Physics Lab led one of two teams that made the discovery. While they made their discoveries with ground-based telescopes, Andrew is also excited about the recent and still-to-come observations by robotic spacecraft that get up close and personal

with asteroids. Let's talk about what's to come. We talk pretty frequently on this program about the Dawn mission, among others, which course, next year is going to reach its first target, Vesta. Are you looking forward to this close-up view of a couple of big asteroids? Oh, very much. This is a wonderful time to be studying asteroids. We've been learning so much just in leaps and bounds from the work that Neil Shoemaker did at Eros.

The Hayabusa mission was a tremendous success, and to have our first look at these really large objects that are practically planets in their own right, I guess depending on who you ask, we're going to learn an amazing amount from Vesta and from Ceres in particular. Are you particularly interested in Ceres, which is kind of a world unto itself? I

mean, it's spherical. It's true. I am very interested in Ceres. I think Vesta is also going to be amazing. And of course, the fact that we have meteorites that we've associated with Vesta helps that effort. But I think Ceres is really kind of an unsung target. It is large. It is the dwarf planet, according to the IAU. It's thought to be very ice-rich in its interior. It's by far the largest object out there. There's evidence that it's differentiated, like I said, into an ice shell over a rocky core. I don't think we have any idea really what we're going to find in terms of its geology. Definitely exciting times. Where else is your own work taking you? I'm going to be starting a project soon with my collaborators,

trying to kind of bridge the gap, in a sense, between the asteroidal observations we've made and some of the observations of the Moon that spacecraft have made. There's these findings of water on the Moon by the M-cubes on Chandrian-1 and VIMS on Cassini and the Deep Impact spacecraft. And there's been some suggestion that that water was created by interactions with the solar wind. Those same sorts of interactions should also be occurring on the asteroids. And so we're going to try to make similar observations of both to try to test those

sorts of theories. We can also do things for observations of the moon that those spacecraft now can't do since they're all either defunct or at other targets. So we can observe places over the course of different lunar phases and return to them again and again. We can tweak our observations and just come back the next month and try to make more of them. So I think there's still a lot to be done observing the moon from the ground. Speaking of ground-based instruments, what kind of role are the new, you know, mega telescopes going to play in the research that you're able to do? We were just a few weeks ago on this program talking about the giant Magellan telescope, among others.

Yeah, the big telescopes, they've already been sort of revolutionizing a lot of study, thousands of asteroids in the course of its survey. The work that WISE has done is another example of that, where something that was intended for astrophysics primarily has done an amazing job of generating great data for small bodies and asteroid studies. Pan-STARRS, I believe, just found its first NEO. When the LSST comes online, we expect it to also generate some great data for asteroids. When you were a kid growing up in New York, what got you interested in all of this stuff so far out there? I think I started out sort of in a typical way where I wanted to be a fireman,

and then I wanted to be a fireman, and then I wanted to be an astronaut. When I was six or seven years old was when the first real, a big wave of robotic spacecraft were launched by NASA and operated by NASA. So the Viking spacecraft landed on Mars. I remember vividly seeing the newspaper and seeing the picture of the blue sky on Mars, which was then corrected but made a big impression. Voyager went to Jupiter and Saturn as I was a child. And of course, Carl Sagan's Cosmos came out, and that had a tremendous effect on me and a lot of my peers in the field right now, actually. Let's hope that your work inspires some more young folks to move in the same directions, because this remains a very exciting field. And, Andy, thank you for taking the time.

I certainly hope that we can check back with you, maybe as Don begins to tell us more about the second largest of the asteroids out there beyond Mars. That would be great. Thank you. Andy Rivkin, born in New York but now in Maryland at the Johns Hopkins University Applied Physics Laboratory. By the way, have you become an Orioles fan? Oh, no, no, Yankees. I grew up a Yankees fan, and I'm still a Yankees fan.

I've been going to see the Nationals, though, down in D.C. Yankees, huh? Well, nobody's perfect. Yeah, I hear that a lot. Anyway, Andy, as you can hear, is at JHU's Applied Physics Lab, and he specializes in observing asteroids and analyzing their compositions. His team, along with another, have independently verified for the very first time this presence of water on the surface of an asteroid 24 Themis.

We'll be back to talk about the night sky with Bruce Betts. That's just a few moments away. So Bruce Batts is the Director of Projects for the Planetary Society, and time once again to talk to him about what's up in our solar system and the universe, and also to thank him for helping to make one of the most enjoyable parts, at least for me, of the open house video, which is now up on the Planetary Society website. It was entertaining. Yeah, we had good time. You had some good props too, though not quite as good, I think, individually as the electric tape measure that Dave Doody had. Okay. I'm sorry. I didn't mean to disappoint you. Mine cost more. Yeah, well,

you know, and yours is made of titanium, too. So, okay, never mind. I take it back. What's up in the night sky? Copy of mine's going to Mars, this moon Phobos and back. Mine has organisms in it that we actually know what they are. All right. Not that I'm feeling competitive. All right, I'll move on. I just want you to know how impressed I am with the life experiment that everyone should read about right now. Yeah, too late. At least after they hear you tell us about the night sky. In the night sky, there is over in the west after sunsets, Venus looking extremely bright.

And there are two other planets over there and a bright star, but they all kind of get washed out except for Venus, which just dominates. but they all kind of get washed out except for Venus, which just dominates. But if you look carefully or pull out some binoculars, you can see Mars reddish to the right or upper right of Venus. You've got Virgo's bright star Spica near that farther to the right. And way to the right, really low, is Saturn on the horizon. And you can also look in the other part of the sky over there in the east, and all through the evening, Jupiter looking extremely bright. And if you pull out some binoculars, Uranus, which we'll talk about in a little bit, will

be within three degrees of Jupiter, roughly. So not that far away. Probably want to go find a finder chart on the web for that. Okay. On to this week in space history, I know you'd want me to mention that in 1966, Star Trek premiered. Oh, thank you for including that. Trekkie that I am.

2004, the Genesis spacecraft crash lands on its return back to Earth, and they've pulled lots of science out of that after putting the pieces back together. In 1975, Viking 2 was launched. Groovy. Let us move on to... How fast are you going?

Because I think there was some time dilation there. I'm going really. It's... Oh, I'm sorry. I should never record at 0.9 the speed of light. Ha, ha, ha, ha. Jupiter. It's big. It's massive. Its mass is two and a half times the mass of all the other planets in our solar system combined. Say that again? The mass of Jupiter is two and a half times the mass of all the other planets in our solar system combined. You put all the others together, and Jupiter is still two and a half times the mass. Impressive, isn't it?

It certainly is impressive, because I would have thought that, you know, with Saturn and Uranus and Neptune helping out us puny guys, that that would not be true. But that's a big darn planet. King of the planets. You know, there's a reason they call it that. Speaking of kings...

What? Oh, okay, that king, yes. We asked you in the trivia contest, how many distinct rings, at least as we know now, does Uranus currently have? How'd we do, Matt? I'm just going to tell you that we had a first-time winner. Benjamin Ray Pearson. Benjamin Ray Pearson in Tucson, Arizona, who came up with the answer, 13 rings, currently known

right now around that planet of Uranus. And you won't be surprised to hear that we got some interesting other factoids from listeners. But we are going to send Benjamin a Planetary Radio t-shirt. What'd we learn, Matt? What'd we learn? Well, here's the most interesting one, I think. Now, of course, Uranus discovered by William Herschel. And only about eight years after he discovered it, Bill said that he thought he saw a ring around Uranus,

which is not to be confused with a similar joke. But that wasn't confirmed. I mean, those rings weren't confirmed until almost 200 years later, as a couple of smart listeners pointed out. Do you think there's any chance that he actually saw one of the rings of Uranus? I suppose there's always some chance, but it seems incredibly unlikely since they are really, really dark rings and very thin and hard to see. So are we sure that he was talking about the planet and not some other joke, right?

No, he had not moved on to teaching anatomy at that point, so I think he was talking about Uranus. This is absolutely a fact. He originally wanted to call it George's Star, after, of course, the king at that time. It was Ian Jackson, a Britisher himself, who told us that he still prefers that original name of George's Star. So, crazy planet for a mad king, I suppose.

Wacky, wacky planet. Tilted on its side. Craziness. Speaking of the outer solar system, I got a new question for you. Please. For every three orbits that Neptune makes, how many orbits does Pluto make? And I decided to go with that one instead of the one where they're each on trains coming across the country and they have different speeds and you have to figure out when they meet.

So for every three orbits Neptune makes, how many does Pluto make? I remember that very math question. If Uranus was on a train headed west. Okay. Yeah. I'm glad you rephrased it that way. Go to planetary.org slash radio. Find out how to enter. I'm glad you rephrased it that way. Go to planetary.org slash radio. Find out how to enter. You got until the 13th of September to get us that answer. That'd be Monday, September 13 at 2 p.m. Pacific.

And let's give away another copy of Mary Roach's Packing for Mars, since we have another one or two to give away. We're going to give one away next week. Now, anybody who answers this one correctly and gets chosen by random.org, you're going to get that very funny and very clever and informative book. All right, everybody. Go out there, look up at the night sky and think about lint traps and what they collect. Thank you.

Good night. He's Bruce Betts, the Director of Projects for the Planetary Society. He joins us every week here for What's Up? And I'm going to go check the dryer right now. Planetary Radio is produced by the Planetary Society in Pasadena, California, and made possible in part by a grant from the Kenneth T. and Eileen L. Norris Foundation.

Clear skies. Thank you.