Planetary Radio: Space Exploration, Astronomy and Science - Still Making a Deep Impact, with Jessica Sunshine

Episode Date: December 26, 2005

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Still making a deep impact, 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. It made a deep impact on all of us half a year ago, and an even deeper one on Comet Tempel 1. Remember what a kick that was? Jessica Sunshine hasn't forgotten. This mission scientist is still pouring over the data.

She'll talk about some of the very surprising things we've learned. And stick around for the last visit ever with Bruce Betts. Okay, okay, the last one in 2005. Just enough time for a handful of space headlines. Ring around the big blue planet. Thanks to the Hubble Space Telescope, two new ones have been found at Uranus. The story is at planetary.org. The U.S. Congress has approved NASA's budget.

Included in the bill is a directive that NASA create a program to find and track all near-Earth objects that are bigger than 100 meters. And while we'll have much more on the returning Stardust probe next week, we should note that the spacecraft and its cargo of comet and interstellar particles comes home on January 15. Are there spots on Mars where future astronauts will be protected from deadly radiation? As usual, Emily has the answers. I'll be right back with Jessica Sunshine. Hi, I'm Emily Lakdawalla with questions and answers. A listener asked,

Are Mars' local crustal is much weaker than Earth's. But Mars Global Surveyor has recently discovered that patches of Mars' crust are magnetized strongly enough that they act like magnetic umbrellas. Mars' mini magnetospheres ward off the solar wind in their vicinity. However, they don't have any effect on the sun's ultraviolet radiation. The ultraviolet radiation still reaches the lower levels of the atmosphere and surface. Ultraviolet radiation is, of course, one cause of cancer in humans. But it does seem that visiting these magnetized areas of Mars's crust could protect future astronauts from the harmful effects of the solar radiation. Stay tuned to Planetary Radio to find out more.

Jessica, sunshine got to bask in the glory of deep impact success last July 3rd as the spacecraft's impactor made its spectacular and explosive rendezvous with Temple 1. The light of that event is revealing never-suspected knowledge about these romantic objects called comets. Dr. Sunshine is chief scientist for the Advanced Technology Applications Division of Science Applications International Corporation, or SAIC.

She's also a co-investigator on the Deep Impact team. Jessica, thanks so much for being part of this last-of-the-year planetary radio where we hope to get an update on the Deep Impact mission. My pleasure. So what has Deep Impact taught us about comets, or at least about one comet? Well, we've learned an awful lot about the structure, the internal structure of the comet. Perhaps that's the most surprising result that we got. Tempel 1 is very fluffy, sort of something on the order of talcum powder,

if not lighter and smaller in particles. That's why the impact was so dusty and why we couldn't see through it. And we've also beginning to understand where different materials are located in the comet. Your colleague, Micah Hearn, who has been on the show, was quoted somewhere as saying, gee, you know, they're going to have real trouble trying to latch on to one of these things with an upcoming mission because it's powder. Correct. I mean, it's more powdery than the, I guess, good high-altitude snow.

So it is going to be an engineering challenge, I think, as well as just trying to stay on the surface given its low gravity. There have been some other nice surprises, I think, and particularly things that you've been in the forefront of discovering because of your specialty, which I guess you should talk about a little bit, and can be summed up as remote sensing and using spectrographic data. Right. My specialty is spectroscopy,

and what we do there is look at how light is reflected or emitted off the surface at various different wavelengths. You can think of it as colors with lots of precision. Simple spectrum is, of course, the rainbow. But we look farther into the ultraviolet and farther into the infrared than human eyes can see. And based on those responses, we can identify different materials. Yeah, as we've heard many times on this program and as most of our audience knows, and materials. Yeah, as we've heard many times on this program, and as most of our audience knows, you can tell from the light either reflected or generated by material, you can get pretty good clues

as to what it's made of. That's correct. And I guess you have, at least on this mission, or maybe it's broader than that, specialized in the light that's been reflected. Yes, mostly worked on reflected light. I've done a little bit of atmospheric work here on Earth and of late have been doing a fair amount of it on the coma of Temple 1 in terms of emission, gas emission features. What additionally have we learned

from Deep Impact, particularly about the composition of Temple 1? I've read that a lot of it has to do with water and organics. Absolutely. Those are the two major species that we're dealing with, and, of course, they're near and dear to us because they are the ingredients that are necessary, if not sufficient, to produce life. I was hoping you'd say that. Yeah, which doesn't mean that they came from comets,

but it's certainly possible and maybe some people would say likely that they contributed to the building blocks of our origins. But in terms of Tempel 1 itself, it's becoming a very interesting story. My personal bias is that we are now understanding it as a geologic body. Sometime a couple of hours out, Tempel 1 transitioned from an astronomical target to a geologically resolved body. It's really opened up astronomical target to a geologically resolved body. It's really opened up our eyes to understanding how the comet works, which is directly linked to the composition.

And probably the most significant thing that's come out of the geology is that Tempel 1 is layered. We're also seeing similar results in the composition. We see differences in the amount of water versus organics that came out as a function of time from the ejecta plume, the original vapor plume, which is an indication that there is layering. We're starting to see differences in surface morphologies that may or may not have compositional implications. And it's really causing us to sit back and think about how did this body get put together. The sort of original concepts were that it was kind of a rubble pile that aggregated materials from the interstellar media kinds of processes,

which seems to be the case in that we have very fine particle material, and yet we have this obvious signature of layering, which is a bit puzzling yet. You're dealing with this, you said now, this transition from an astronomical to a geological object in the same way that we now are learning about Mars as a geological object as we crawl around and look at its composition. Oh, absolutely. This is probably more dramatic in that we've at least had other images of Mars.

This was the first for this particular comet, and by far the best resolution we've had on any comet. Are you finding more or less of the expected components of Comet Tempel 1 than you expected before Deep Impact got there? Well, it's not a question of, well, let me try it this way. There's two issues. We found mostly the materials we expected. The question was not necessarily how much but where

and what causes them to come out at different times and where are they located within the body and what does that tell us about how they're processed. I think probably the single most surprising compositional result to date was that when we looked at the ejecta, we increased the amount of water and carbon dioxide by a factor of about 10. Wow. But the organics increased by a factor of 20. And that was certainly a surprise. What does this, particularly in the case of the organics, does this begin to suggest something about the early composition of the universe or at least our solar system?

You know, we're still flushing it out. We're trying to understand the differences between what may be, let's say, residuals from prior outbursts that may increase the organic content near the surface versus what is really original compositional gradients. And it's a little early to say yet. What about the abundance of water and carbon dioxide? Same for those, a little early to say? Well, what we're in the process of doing right now is trying to understand, again,

it's not so much that they're there, but where do they come from and how do they get there? understand, again, it's not so much that they're there, but where do they come from and how do they get there? We're in the process of understanding how variations that we see actually within the coma, the atmosphere of Temple 1 itself, are related to potential different areas on the surface and different outgassing events. We're also trying to compare and actively working on understanding the difference between the materials that came out from our natural impact and the outburst, I'm sorry, our man-made impact and the natural outburst that we caught about a week before the impact. We saw similar but not the same materials in different abundances,

and again, that's likely to tell us something about the layering and where different materials are located. I had not read about this. Now, is this the natural outflow of material as a comet nears the sun and just stuff boils off? Well, what happened was, in retrospect, perhaps not too surprising, but Tempo 1 probably is the best-studied comet since Halley, and in particular because we had this extensive ground-based campaign

as well as a bunch of our space-based telescopic assets, we're watching the comet both before and after impact to get a baseline to compare the impact event, as well as our spacecraft was taking data every four hours. We had the best temporal sequence of cometary activity, very close to perihelion, that anybody's had. And we saw in various instruments a series of outbursts. That is the natural outgassing, which we assume at this point, but certainly haven't concluded, has something to do with areas heating up and releasing their gases.

Only a few of them were able to get compositional information, but we are, have been able to, now that we understand the size, the orbit, the period, and the shape and pole location of the comet, we can actually trace those individual outbursts to where they came, or at least the general area that they came from. And some of them seem to be recurrent, others don't. the general area that they came from. And some of them seem to be recurrent. Others don't.

We had one outburst that happened repeatedly from the same area several periods before the encounter, but the one right before the encounter didn't happen. So, you know, nature's always mysterious. But I think we will learn an awful lot about that part, which is, of course, a very important part of cometary processing. We'll have more from Deep Impact co-investigator Jessica Sunshine when Planetary Radio continues. This is Buzz Aldrin. When I walked on the moon, I knew it was just the beginning of humankind's great adventure in the solar system.

That's why I'm a member of the Planetary Society, the world's largest space interest group. The Planetary Society is helping to explore Mars. We're tracking near-Earth asteroids and comets. We sponsor the search for life on other worlds, and we're building the first ever solar sail. We didn't just build it. We attempted to put that first solar sail in orbit, and we're going to try again. You can read about all our exciting projects and get the latest space exploration news in depth at the Society's exciting and informative website, planetary.org. You can also preview our full-color magazine, The Planetary Report.

It's just one of our many member benefits. Want to learn more? Call us at 1-877-PLANETS. That's toll-free, 1-877-752-6387. The Planetary Society, exploring new worlds. Welcome back to Planetary Radio, where we're talking with Jessica Sunshine, a co-investigator on the Deep Impact mission. With all this new data about one comet, I had to come back to the question I started with. I started out by wondering,

what have we learned about comets, or have we only learned about Tempel 1? I mean, how much of what we are learning can be applied to these thousands upon thousands upon thousands of other objects that we call comets? Well, I think a fair amount of it is. First of all, Tempel is a very, from every way that we can measure it, is a very typical comet, at least for a Jupiter family comet. It's middle-aged, if you will. It's neither particularly young or particularly old. And what we're very much focusing on is the processes that are occurring on the comet, which have to occur on others. For example, there's no question that if Temple 1

is producing outbursts on a regular basis as it approaches the sun, so much other comets. And in fact, people are now going back to previous data sets where they might have seen something funny that they ignored on other comets that may in fact have been outbursts. Wow. And I think the structural component, the geologic history of Kem Temple 1 is telling us a lot, yet on the other hand, it is very different from VILD 2 geologically. So comets have clearly gone through different origins that we need to understand. It's fairly similar to Borelli from what we can tell, but VILD 2 is a different beast.

Is it still fair, do you think, to describe these using the old metaphor of a dirty snowball? It's probably fair. I think we're, from what we could tell at least of the ejecta, the dust-to-gas ratio is about one-to-one. So, you know, you could decide whether it's a snowy dirt ball or a dirty snowball. I think we kind of expected it to be much more clearly dominated by organics than it was. I'm sorry, by gases than it was. So we expected more water to dust than we saw.

Here's the question that you probably were expecting, particularly as, you already know, don't you, as a few thousand Planetary Society folks and listeners, I bet, are wondering how big that crater is. And, of course, somebody's hoping still to win a prize out there out of this.

Well, I think one of my colleagues said a couple of days after the impact, we know who lost the bet. Right now our official statement, I believe, is that it was somewhere between 100 and 200 meters. Okay, and I don't think a winner has been named yet. Yeah, I think I'm correct that they're going to do a lottery based on the people who came in with that range. The problem, of course, is that we had so much not only dust, but it was very fine submicroscopic dust.

We couldn't see directly the impact site, but we've done a lot of work in trying to infer it based on cratering physics as well as some constraints of areas that we could clearly see before and after the impact, which give us upper bounds on the sides of the crater. What's the future for Deep Impact? The spacecraft itself is kind of in space mothballs, if you will. It's on its way back to the Earth, which makes it possible for us to change its course and point it somewhere else. We're going to be putting an extended mission proposal, which, if it's selected,

We're going to be putting an extended mission proposal, which, if it's selected, would head us toward the comet Botan in 2008, I believe, which would give us an opportunity to have a look at yet another comet to understand, you know, the question you asked, how representative is Tempel 1 and particularly the processes that we saw. Well, good luck with that request for an extended mission. At the moment, your spacecraft is not the only one returning from a comet. It's a good time for comet research with Stardust returning to Earth, bringing back little

comet bits and maybe some interstellar stuff, not long after this program is heard. In fact, we're going to devote next week's show to a little preview of that return of Stardust. Is there anywhere where these two missions intersect, Deep Impact and Stardust, at least in terms of the data that you might hope to see from Stardust?

Well, absolutely. First of all, already the imaging results have been very helpful, comparing VIL-2 to Temple 1, in order for us to understand, because they're so different, the origin of comets and what history they've come through. We have to be able to put both of those into the same scenario. Obviously different histories, but they have to have some commonality to them. And that's something that's been a very important constraint into our thinking of our own results. The samples themselves are critically important and particularly close to my heart

because they're going to answer a lot about the structure. What is the scale and how are these things put together of the small materials that we now know make up the comet? It's our only real look at how they're put together. And, of course, the theory is that it's very similar to the interstellar dust that we see, but we won't know until we see it. And hopefully we're going to see it soon. And hopefully your team will get to take another look at yet another comet. But we knew moments after that impact, that deep impact,

had made itself one of the most successful interplanetary missions of all time. It was quite a fun experience. Well, congratulations once again for that. And we'll check back as more data becomes available. Great. Thanks so much for being on Planetary Radio, too. My pleasure. Jessica Sunshine has been our guest.

She is chief scientist of the Advanced Technology Applications Division, a fascinating company called Science Applications International Corporation, which if we had time we would talk more about, but also a key player in the science team for the Deep Impact mission, which returned all that wonderful data from the big hole it made in Comet Tempel 1 just about half a year ago. We'll continue Planetary Radio with What's Up and Dr. Bruce Betts, our last What's Up edition of the year, right after this return visit from Emily. I'm Emily Lakdawalla, back with Q&A.

If local magnetic fields on Mars can shield the surface from the solar wind, could they also protect astronauts from cancer? The problem with this question is that the first astronauts sent to Mars will be exposed to solar radiation long before they land. The majority of their exposure will happen not during any surface operations on Mars, but instead during the long journey to Mars. What is the risk that astronauts face from this exposure? First, consider the risk that humans on Earth face. It's big.

A healthy, 40-year-old, non-smoking American male stands a 20% chance of eventually dying of cancer if he stays on Earth. How much is that risk increased during the long journey to Mars? It could be as little as 2% or as much as an additional 20%. It's probably true that many young astronaut candidates would be willing to accept a doubling of their risk of developing life-ending cancer in order to become the first human to walk on Mars. Eventually, our leaders will have to face the ethical question

of how great a cancer risk we are willing to allow our brave explorers to take. Got a question about the universe? Send it to us at planetaryradioatplanetary.org. And now here's Matt with more Planetary Radio. It's the last Planetary Radio episode of the year 2005, and therefore the last installment of What's Up with Dr. Bruce Betts, the Director of Projects for the Planetary Society. Happy New Year, Bruce. And happy end of the year to you, too, Matt. So what's up?

Is that kind of a half-full, half-empty thing? It could be. I'm a half full guy, so I didn't even realize that. That's why we enjoy you so much. Well, then you should be half full of delight with what's up in the night sky. Got evening sky, of course, Venus still bright, but starting to drop away. But you can see it just after sunset, looking very bright in the west. Mars now basically in the south after sunset and fading, fading, fading, but still orangish and still looking like a bright star. And in the pre-dawn sky, you've got Jupiter, and Jupiter is up fairly high now in the east just before dawn.

And you can also catch Saturn rising around 8 p.m. It's below Castor and Pollux, the twin stars of Gemini. I haven't seen Saturn lately. I've got to get out there now that it's up in the evening. It's up in the evening. It's very, very good in the evening. And take out that lovely telescope of yours and check out some rings. Thank you.

I will. And, of course, don't miss the meteor shower. Oh, yeah. Those quattrotids or whatever they're called. Those quattrotids. Did I get it right? Yeah. As close as I'm getting it. It just doesn't say much. Of course, don't miss the meteor shower. Oh, yeah, those quadratids or whatever they're called. Did I get it right? Yeah, as close as I'm getting it. It just doesn't say much.

Yeah, it's peak on the January 3rd, 4th, and if you go out there and stare up at the sky, maybe you'll get up to a meteor a minute on average in a dark site. And very little to no moon to interfere with it, so a good thing other than if you're chilly in the northern hemisphere. But you Australians have a great time out in the warm evening. Surf's up. Yeah. Okay, let's move on to this week in space history. I know you're excited. 205th anniversary.

205th anniversary on January 1st of Giuseppe Piazzi's discovery of the first asteroid to be discovered, Ceres. Is that right? He started right out with the biggest one. Sure. But Ceres is the biggest one, right? Isn't it? No? Yes.

Oh, okay. Yeah. Just started right in. I guess that kind of makes sense. Well, it would be the easiest one, okay. Yeah, just started right in. I guess that kind of makes sense since it's easier to see. Well, it'd be the easiest one to find. Yeah, yeah, yeah. Okay, let's move on to a human spaceflight update. Those Progress supply ships, those darn reliable things,

launched by the Russians out of Kazakhstan, taking some Christmas presents, some food, some supplies. Successful launch at the time of recording. They're not quite docked with the International Space Station, but will be shortly and before this airs. So that's good. And getting some new supplies up to Bill MacArthur and Valerie Tokarev. Tons of fun for the guys on the ISS. Is it?

It is. It is tons of fun. Nearly three tons of fun just in the supplies that it's going there. On to Ramblin' Space Fact! That was positively majestic. Oh, thank you. Speaking of majestic voices, on Mars, if you could speak, your voice would sound much lower and fainter. And we've had demonstrations of that on Planetary Society website.

We have on Planetary Radio, but I just wanted to remind people. And you can go to planetary.org slash sounds, and you can hear the Marsinator and hear famous people like me. Yeah. No, there are real famous people on there too, like Ray Bradbury. And Bill Nye, I think. And Bill Nye, having their voices altered like they would sound on Mars. But what's interesting, to give you a bonus random space fact,

is that your voice on Titan would sound very similar, despite them being such different atmospheres. Oh, yeah. Because you've got a serious temperature difference that's causing the main difference on Titan and a big compositional difference as well as temperature on Mars compared to the Earth. Oddly, they result in nearly the same shift in sounds. Not that anybody's going to be testing this in person anytime soon. No, and then even

if you went there, it'd be kind of chilly and, you know, painful. Yeah. But just as you're pondering things, as you're musing, as we so often muse on this show. Shall we muse on to the trivia contest? Yeah, let's do that. We asked you, what was the first wheeled vehicle on the moon? The first wheeled vehicle on the moon. Turns out all those wheeled vehicles were partying on down to the surface within a very short period of time. How did we do?

Very close call here. We had one entry that I actually had to do some research on. Paul Corman of Bellevue, Washington, talked about the MET, which I had never heard of. You had. The Modular Equipment Transporter. It was kind of like a rickshaw loaded with stuff for the astronauts to pull around on Apollo 14. But I determined that that actually was after the first wheeled vehicle,

the one you had in mind, Luna Cod 1. Yes, Luna Cod 1, the Russian vehicle on the Luna 17 lander, was the first of the wheeled vehicles on the moon, followed by the Met, followed by, of course, the Lunar Rover on Apollo 15 through 17, and followed by another Lunokhod as well. And our winner was Del Parma. Del lives in, I guess it's Wigan, England, Great Britain. And, Del, you're not going to get a Planetary Radio t-shirt.

You're going to get a mug. This was the week we were giving you off that mug you were talking about. That ugly mug. No, that beautiful mug. It's a beautiful mug. Oh, you were talking about. That ugly mug. No, that beautiful mug. It's a beautiful mug. Oh, you were talking about me. Yeah, no, the mug is actually beautiful with a beautiful landscape from Spirit, the Spirit rover on Mars, and three reasons why you'd rather live on Mars.

Very clever stuff. Fun stuff. If you aren't our winner, you can find things like that on the Planetary Society website, planetary.org. Now, what are we doing on Trivia Contest, Matt? We ain't doing one. We would normally now give you the new Trivia Contest question, but not this week, folks. Sorry about that, because in two weeks, we're going to have a reprise, a previously owned version of Planetary Radio. It's just because of vacation schedules and so on.

But we think you'll enjoy it. We had a lot of interest in the Planetary Society's 25th anniversary show that we did excerpts from with all that incredible list of guest stars, you know, Bill Nye and Buzz Aldrin and Ray Bradbury and Don Golden, the former NASA administrator. So we're going to do that during the week of January 9th. So no contest this week, but come back next week. That would be Dan Golden. What did I say?

Don Golden. Don? Oh, that's so stupid. I'm sorry. I wouldn't go that far. No, I would. I would. Okay.

Well, anyway. Anyway, we've corrected that. So I feel at a loss without a trivia question, but we'll be back next week with more trivia. We will, and I just want to say that it has been another delightful year of working with you on What's Up, this very enjoyable portion of our little radio show that heads out to people every week. The little radio show that could. That could. And indeed, it has been an honor working with the likes of you, Matt.

Thank you. Thank you, and have a wonderful and happy new year. Everyone, including you, Matt, go out there, look up at the night sky, and think about something really fun you're going to do during this next year. Thank you, and good night. He's Bruce Betts. He's here every week, thank goodness, for What's Up. Planetary Radio is produced by the Planetary Society in Pasadena, California.

Start us next week. Happy New Year, everyone. Thank you.