Planetary Radio: Space Exploration, Astronomy and Science - We're on Asteroid Watch With JPL's Don Yeomans

Episode Date: August 17, 2009

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We're on Asteroid Watch, 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 of the Planetary Society. There's a new website designed to keep you up on the latest news and science regarding those space rocks that are found throughout our solar system. It's just a matter of time before some of the bigger rocks have an encounter of the violent kind with our delicate planet. Don Yeomans of JPL returns to tell us what we'll find at Asteroid Watch.

Emily Lakdawalla continues the deep dive into Jupiter she began last week. She'll reach the core of the matter in this installment of Q&A. And I'll help Bruce Betts celebrate our friend Marvin the Martian as we examine the night sky and hear another random space fact in What's Up. You'll also want to get in on Bruce's new contest. What would you tweet to Marvin or any other alien? Not including the one stuck in District 9, of course. Bill Nye, the planetary guy, is out of town and has the week off.

My colleague Amir Alexander has a couple of great news stories posted at Planetary.org, beginning with news from the Kepler exoplanet finding spacecraft that we've talked about on this show. Even though it is still in its shakedown phase, Kepler has managed to analyze the atmosphere of a known exoplanet, a so-called hot Jupiter. Then there's WASP-17. That's the shorthand name of yet another exoplanet just found. This one is going the wrong way. Every other planet we know of orbits in the direction that its star rotates. Scientists have some thoughts about how this retrograde variation on Newton may have happened.

And don't forget that Emily is back at the reins of the Planetary Society blog. She has assembled her own Saturn at Equinox Cassini mosaic for your pleasure. You can check out the dark rings at planetary.org. Here's a quick update. Some of you may remember Mars Exploration Rover project manager John Callis telling us that Opportunity was heading back to investigate a big rock it had passed. Sure enough, NASA and JPL have confirmed that that half-ton or bigger object is an iron-nickel meteorite. I'll be right back with Don Yeomans. People are fascinated by asteroids,

especially the ones that come uncomfortably close to home, the Planetary Society's support for the discovery and tracking of near-Earth objects came out on top in a recent survey of the organization's members. And the United States National Research Council just issued an interim report on this country's NEO survey and hazard mitigation strategies. But that cloud of metal and rock generates enormous scientific interest as well, including new enthusiasm for a human mission. Asteroid Watch is a new website loaded with features and news about, well, asteroids.

It's where you can see Don Yeomans and his colleagues in their hometown videotape on CSI, which in this case stands for Comet Asteroid Scene Investigation. Don has talked to us about NEOs before on this program. He manages NASA's Near-Earth Object Program Office at the Jet Propulsion Lab, where the new site is based. I talked to Don a few days ago. So, Don, I had no idea that you guys at JPL were joining the CSI franchise until I found that clip on the website. It must have been fun. Well, it was fun. It's a nice way to draw attention to our activities.

It was a very nicely produced video, and we'll put up the link, of course, we'll put up the link to the Asteroid Watch website where people can watch the entire thing for themselves. But I'm sure that people are going to want to explore the other resources that you've put up there. How long did it take to put it together? We have had a website, Near Earth Object, neo.jpl.nasa.gov, up for several years. But that one is aimed primarily at the professional community and so we wanted to have a public friendly uh website that introduced asteroids and near-earth objects and so beginning about six months ago we started looking at what would it take to present a more friendly

face to uh near-earth objects and uh we've been working on it over those. That's pretty quick to put together a website as rich as this, six months. And it certainly has been getting a lot of media attention. Did that surprise you? Not really. I think this is a topic that generally gets a lot of interest with the media and the public, but there's a lot of misinformation out there as well, and so we wanted someplace where the public could go to get important and interesting and factual and reliable data, sort of a one-stop shopping for near-Earth objects, if you will. And I'm looking at the homepage right now, as a matter of fact.

It has a news section, and the top story is the discovery that this one asteroid is not one asteroid. It's a triple asteroid. Yeah, that's right. Marina Brozovic and her colleagues here at JPL used the Goldstone radar recently to determine that this object, which is called 1994 CC, is not just a near-E Earth object, but it's actually a triple system. It has two moons of its own, and it's the second near-Earth object that actually has two moons. Very surprising, I might add. Do you suspect that we're going to discover that a lot of what we've, in the past, taken to be single asteroids are really systems or asteroids with companions?

Well, to date, we have something like 15% of the near-Earth objects are, in fact, binaries. And now we have two objects that actually have triple systems. So it was surprising initially, but now that we've found so many, it's not a surprise any longer. Is this kind of a golden age for asteroid research? And I'm thinking primarily of the fact that we've been able to image so many asteroids and have visited a couple, more than a couple. Yeah, that's a good point. I think we are really in the golden age of asteroid research in the sense that we've

had a couple of spacecraft encounters. in the sense that we've had a couple of spacecraft encounters. We've got a sample return, hopefully, from the Hayabusa spacecraft coming back next year. And, of course, the radar, they have been imaging several objects, and their resolution is such that it's almost like a spacecraft flyby. Don, the focus certainly seems to be mostly on asteroids. After all, the site is Asteroid Watch. Are comets getting second billing here?

Well, comets are an important component of the near-Earth objects. But in terms of numbers, asteroids in near-Earth space outnumber comets by 100 to 1. So it really is more of an asteroid watch than a comet watch. But that doesn't mean we're ignoring the comets. We will certainly monitor any comets that get close to the Earth and put them on our website and on our widget, which gives close approach information that's upcoming. But realistically, we don't expect too many comets to get that close that often, whereas for asteroids, it seems to happen every few days. You know, I'm glad you mentioned the widget, which is one of the interactive features of

not just the website. You don't need to go to the website to enjoy the widget, but you've also got a Twitter account and an RSS feed. It seems like you're providing all kinds of ways for people to stay up on what's going on with these rocks that could threaten our planet. Well, that's true. The hope is that we're providing a friendly interface for folks who want to know about near-Earth objects, not just the hazards, which seems to get all media attention, but the fact that these objects are important scientifically,

representing the leftover bits and pieces from the early solar system formation process. They probably brought to the early Earth much of the water and carbon-based molecules that allowed life to form, and then they punctuated evolution with the subsequent impacts, much like the one that wiped out the dinosaurs. So we really owe much of our existence and our position atop the food chain, we humans, to near-Earth objects. Although they are a threat, and some of them, they also are scientifically important and extremely important for life on Earth. Did some of these items, factoids you just mentioned, make your top ten list on the website. Well, yeah, actually we did include a couple of items along those lines.

In fact, the first one gives credit to asteroids. The first one on the top ten is thanks to asteroids, noting that they probably did provide much of the Earth-based water and carbon-based materials, the building blocks of life. And then further down we note that in the future, if you're going to build structures in space, asteroids may provide the minerals and metals to do that. And comets, which are about 30% water, could provide water and break the water down into hydrogen and oxygen, which is rocket fuel, the most efficient form of rocket fuel.

So comets and asteroids may well provide the raw materials for interplanetary structures and interplanetary travel, providing the rocket fuel and water that is necessary to sustain life in space. So they're extremely important from a number of points of view, not just the hazard point of view. That's Don Yeomans, manager of NASA's Near-Earth Object Program Office at JPL. We'll continue our conversation in a minute. This is Planetary Radio. Hey, hey, Bill Nye the Science Guy here. I hope you're enjoying Planetary Radio.

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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. Asteroid Watch is the new NASA website that brings asteroids down to Earth

in a much gentler, though still exciting, approach. You can find it at www.jpl.nasa.gov slash asteroidwatch. And we've also got that and related links at planetary.org slash radio. The site is overseen by Don Yeomans, the manager of NASA's Near-Earth Object Program Office at the Jet Propulsion Lab. the manager of NASA's Near-Earth Object Program Office at the Jet Propulsion Lab. Don is also a senior research scientist and supervises JPL's Solar System Dynamics Group. How do you feel about recent talk of a human mission to an asteroid? Well, there has been a lot of talk about that, in the sense that you'd like to test the technologies that would eventually get you to a human presence on Mars.

You wouldn't just take a giant step and go directly to Mars. You'd like to test some of the technologies on something a little easier to get to, like an asteroid. So I think the crewed missions to asteroids are being talked about in the sense that they offer a stepping stone to Mars. Although they're interesting in their own right, a quick trip to an asteroid by a couple of crew members would certainly test the technologies that would ultimately be necessary to get a couple of crew members to Mars and back. And we want to make sure people understand when you say crew, do you mean C-R-E-W-E-D, not the other kind. Yeah, it's easier spelled.

Let's go back to some of the features of the website, beginning with the widget that you mentioned. Describe that. What's that about? Well, the widget is an attempt to point out upcoming close approaches of objects. For example, we currently have on there an object about 840 meters in size making a close approach to the Earth on August 24th within 19 distances to the Moon. I always think of these things in terms of lunar distances. If they get within one lunar distance, of course, then it's very close. But we are calling out all objects that are potentially hazardous. By that, I mean that they can get within 7.5 million kilometers of the Earth's orbit. And it doesn't matter what

size they are. We list the next five close approaches on this widget. And it's constantly changing as we get more and more information and more and more close approaches. So we call out the date, we call out the size, and, of course, the name of the object, and then we give a little graphic saying, well, it's about the size of the Golden Gate Bridge or the size of a bus or the size of a small SUV. So it's very visual, and it gives you a quick update as to what's coming. According to the website, it's currently available for the Mac in OS X, but to PC folks, I guess they can get it as a Yahoo, do they call it a widget as well?

Yeah, if you go to the website itself, it gives you instructions on how to download the widget, either for PC users or Mac users. We've checked it out on both, and it seems to work fine, unless you've got a really ancient operating system. It might be a problem. Who's maintaining the Twitter updates? Are you doing those tweets? The Twitter updates are run out of our public information office, and we provide the information, of course, but the back and forth with the Twitter is usually handled by our media relations or public relations office with our help, of course. What else is there on the website that you'd want to bring to people's attention?

Well, we have the news notes, of course. We have these top 10 asteroid factoids that I put together. And we have the missions to comets and asteroids that are underway or about to get underway. Dawn, Hayabusa, Epoxy, Stardust Next, Rosetta. There's information on all those missions. We have images, comets and asteroids that can be downloaded. And then we have video and audio presentations. We mentioned earlier the CSI, but we also have interactives. We can

download the widget or the Twitter accounts or the RSS. Back on the overview page, there's a couple of animations that I think are pretty impressive. You can click on the first one, which shows the asteroid Eros rotating underneath the spacecraft. It's really quite impressive. You can click on the first one, which shows the asteroid Aeros rotating underneath the spacecraft. It's really quite impressive. And you can do the same thing for the asteroid Itokawa as it rotates underneath the Japanese Hayabusa spacecraft. So it's quite dramatic simulation, not simulations.

There are actual images of the asteroids themselves. We're just about out of time. I wanted to finish with an asteroid impact in the news in the last few weeks. In fact, our guest last week, Heidi Hamel, came on to talk about that new impact on Jupiter that made initially at least a black spot on Jupiter about the size of the Pacific Ocean. What does an impact like that on Jupiter make you think about our concern for our home planet? Well, I sort of look at it as Mother Nature's way of giving us wake-up calls from time to time.

We had the Shoemaker-Levy 9 impact back in 1994, and then 15 years later, we had yet another impact of Jupiter by probably a smallish, perhaps kilometer-sized comet, although I don't really know how big it was. But the impact scar on the atmosphere of Jupiter suggests it was about that size, perhaps. And so, I mean, if that object of that size had hit the Earth, it would have been an extraordinary energetic event and would have been catastrophic for the region around which it hit. I look at it as sort of a wake-up call that these are objects that we need to pay attention to. And in fact, NASA is paying attention to them in the sense that they have three full-time

observatories looking for them. And once we find them, we can track them and determine whether or not they are a threat. None of them are at the moment, but we haven't discovered but a few percentage of those larger than 140 meters, which is thought to be sort of the limit as to regional devastation and something less. So the kind you were talking about before, the one that currently is on your top five list, the 840 meters, what kind of damage might an asteroid in that class do to Earth? If something of that size were to hit, it would be, well, it would be almost a global event. You know, something on the order of 60,000 megatons of equivalent energy, which is almost inconceivable to think about.

But that one is certainly not a threat, and nor are any others of that size a threat. But we know that because we've been looking for these objects for the last 10 years rather intensively, and we've been focusing on the large ones, the ones that are larger than a kilometer or so in diameter, the ones that could cause global problems, not just regional problems. And we found pretty nearly 90% of them, and none of them and none of them represent a threat. So in a sense, we've retired the risk from objects of that size, at least to the 90 percent level. Don, thanks for watching and please keep it up. Thanks also for the new Asteroid Watch website from JPL, where we can follow along with you. My pleasure. Don Yeomans is the manager of NASA's Near Earth Object Program Office at

JPL, the Jet Propulsion Laboratory near Pasadena, California. We'll be watching the skies with Bruce Betts in this week's edition of What's Up right after we hear from Emily. Hi, I'm Emily Lakdawalla with questions and answers. Last week I answered a question about the composition of Jupiter and explained that its upper atmospheric clouds were made of materials familiar to us on Earth because similar temperatures and pressures prevail there.

But the story is quite different deep inside the planet. Jupiter is about 11 times Earth's diameter and contains almost 300 times as much matter. All that mass means that the planet has an intense gravitational field leading to incredible pressures within it. At the same time, Jupiter retains some of the primordial heat of its formation and is also heated inside as it continues to contract, converting gravitational potential energy into thermal energy. If you descended half an Earth diameter below the clouds, you'd find the pressure to have increased to half a million bars and the temperature to 2,000 degrees Celsius. At that level, the dominant element within Jupiter, hydrogen, acts more like a liquid than a gas.

Go down to a depth of one Earth and pressure and temperature squeeze hydrogen to the density of water and make it behave more like a metal. Go down to a depth of a little more than four Earths and you'll finally get to Jupiter's core. The core is made of hydrogen compounds and also the elements that make up rocks and metals, but with a pressure of 100 million bars and a temperature

of 20,000 degrees, none of these materials behaves anything like their counterparts do on Earth. The core probably churns so violently that all these materials are mixed together, rather than separating into layers of different compositions. Jupiter's core is a little less than twice Earth's diameter and probably contains 10 times Earth's mass, so if you could somehow take its atmosphere away, you'd still have quite an impressive planet. Got a question about the universe?

Send it to us at planetaryradio at planetary.org. And now here's Matt with more Planetary Radio. Time for What's Up on planetary radio bruce betts is the director of projects for the planetary society and he's at the other end of the skype line welcome back thank you very much good to be here how's the night sky uh it's beautiful as always matt over there in the pre-dawn sky we've got venus still spectacular over in the east, can't miss it, brightest star-like object over there in the pre-dawn. Up above it, you can find Mars dimmer and redder. And then in the evening sky, we also have something really bright over in the east, and that is Jupiter, so also brighter than any of the stars out there.

And you'll see it in the east, and by the middle of night, it's high overhead. Can't miss it. By the way, if you're checking out Jupiter in the evening, and you're hanging out in the northern hemisphere, look up above Jupiter. You'll see three bright stars, not surprisingly making a triangle, a big spread out triangle. That is sometimes called the summer triangle, really really Summer Fall more accurately. And that's Vega, Altair, and Deneb, three very bright stars that are particularly visible for we Northern Hemisphere people in the summer. Excellent. I appreciate that. I always like it when you add more than the planets, little highlights like that. All right. Well, we'll try to do that more. But right now, we're going to go on to this week in space history.

Wait, before you do that, did you catch the Perseids? No. But I told a lot of people, too, and they enjoyed them very much. I tried. That night, we were up in Central California on the coast, and it was totally overcast. There was not a chance of seeing them. The next night, of course, it was somewhat clearer, and I still couldn't see anything, because I knew that you said that, you know, it tapers off. It's not like it's all on that one night, but maybe next year. We should do a field trip some year.

Yeah, absolutely we should. Or we can go in December and see the Geminids up high in the mountains and be really cold. Yeah, lovely. On to this week in space history. Ten years ago, Cassini headed to Saturn, oddly enough, flew by Earth, doing that wacky gravitational slingshot thing that they do to help them get out to the outer solar system. And, of course, it's doing great out there at Saturn now. All sorts of neat stuff.

And this also leads me to random space fact almost blew out skype there well you know i've done it before as you know yes which i'm very proud of strangely anyone can break glasses who can break their skype line anywho uh this one actually from emily uh letting us know that between august 10th which you know we've passed but that was the Saturn equinox happens once every 15 years and September 4th things line up between

the Sun, the Earth, and Saturn such that we're actually looking at the dark side of the rings so the rings are nearly edge on but also we're looking at the dark, the unlit side. Boom, boom, boom, boom,

boom. Sorry. So pretty much nearly invisible looking, perhaps invisible. So if you go out, pull out that telescope right now, at least small telescopes, and you look at Saturn, probably aren't going to see the rings. That's a weird, freaky thing.

I'm going to give it a shot. Please do. On to trivia contests. We asked you about our buddy, Marvin the Martian. What year did he first appear in a cartoon? How did we do, Matt? Wow, lots of responses to this. The outpouring of love for this little guy who's tried over and over to destroy our planet is really quite remarkable.

Anyway, it was Lindsay Dawson, our regular submitter of massive and fascinating responses, but who has not won the trivia contest in, as far as I can tell, nearly two years. far as I can tell, nearly two years. Lindsay Dawson was the one picked by Random.org, and he told us that Marvin's first appearance, though not by name, he wasn't named until years later, was July 24th, 1948. July 24th, 1948, almost exactly 61 years ago, in Hair Devil Hair. And what was his doggy's name canine that's right very good work you know what lindsey also did a couple of other people did this too they sent us copies of the early mars exploration rover a patch with marvin saluting us and it says red planet gladiators do you know who was on the Mars B patch back in those days? Me? You wish. Yeah? No, it was David Kaplan sent us the

copy of the Mars B patch with Duck Dodgers in the 24th and a half century. Nemesis of Marvin. Anyway, we are going to send Lindsay, of course, a Planetary Radio t-shirt and an OPT rewards card. Alright, on to the next contest. Time for more fun

and fabulous joy and creativity from our listeners. We got contacted by a former Red Rover Goes to Mars, that's a program we had with MER, a student from Australia, Jackie Hayes. She's now not a student, she's working for a magazine, Cosmos magazine. They're doing a little input contest the next week or so, which you can find at hellofromearth.org, where they plan on beaming to the nearest known exoplanet messages from people on Earth.

I, of course, couldn't resist turning this into a planetary radio contest with us. If you could tweet to aliens send your little twitter message so very short 140 characters what would you say you get one tweet what do you say to the aliens go to planetary.org slash radio to find out how to enter and this time it's just judged on humor that's what i'm thinking just funny that's what we're judging on go to planet yeah i said that let's go on we don't want the That's what we're judging on. Go to Planet... Yeah, I said that. Let's go on. We don't want the aliens to think we're profound. We just want them to crack up and laugh so hard that they decide not to kill us all.

Yeah, that's my concern is they'll kill us all. And maybe if they're laughing, they'll at least not kill us. And we got the 140 character limit? I think so. What do you think, Matt? I think we should stick with that since you said it's a tweet, right? It's a tweet. Yeah.

All right. Well, they've got it. Which you can still find Matt at Matt Kaplan on Twitter. And you can find me at Random Space Fact, all one word on Twitter. Yeah. And I can't remember Emily's Twitter account, but I'm sure it's easy to. It's E-Lock-To-Walla. E-Lock-To-Walla.

E-Lock-To-Walla. You want to get that entry to us by Monday, August 24, at 2 p.m. Pacific time. Okay, that's it. All right. Everybody go out there, look up the night sky, and think about nail clippers. Thank you, and good night. I wonder if Marvin the Martian has nails. You don't really see him, and he has no mouth.

You never see his feet because he's always got his sneakers on. He's Bruce Betts, the director of projects for the Planetary Society, and he joins us every week here for What's Up. What fun. Planetary Radio is produced for your listening and exploring pleasure by the Planetary Society in Pasadena, California. Keep looking up. Thank you.