Planetary Radio: Space Exploration, Astronomy and Science - High Flyin', Cave Divin' Planetary Science with Dan Durda

Episode Date: June 2, 2003

High Flyin', Cave Divin' Planetary Science with Dan DurdaLearn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

This is Planetary Radio. June is here with a very busy solar system summer soon to follow. Welcome back everyone, I'm Matt Kaplan. What's the connection between an F-18 fighter jet and cave diving in Arizona? solar system summer soon to follow. Welcome back, everyone. I'm Matt Kaplan. What's the connection between an F-18 fighter jet and cave diving in Arizona? No, that's not this week's trivia question, but you'll still hear the fascinating answer when we talk with astronomer Dan Durda.

Bruce Betts will have us visiting Venus for the real trivia contest later in the show. First up is Emily, who can't quite get the color adjusted on her TV. I'll be back in a minute with Dr. Derda. Hi, I'm Emily Lakdawalla with questions and answers. A listener asked, Why do the pictures I've seen of Saturn's rings look blue-green or white in Hubble photos, but brownish from Voyager images?

The answer has to do with all of the different steps and electronic devices involved in the production and display of a planetary image. To understand the source of the color differences, imagine walking into a large electronics store. You'll be greeted by a wall full of television screens showing the same vividly colored images. But when you begin to examine the TV images more closely, you'll notice differences in brightness, contrast, and color balance between the screens. Some seem more red, some seem more gray, and so forth. If you start adjusting the relative brightness of green and red on a TV set, you can achieve a very wide range of colors, from realistic to very unnatural. Of course, realistic is a subjective judgment.

So how about planetary scientists? Why don't they always go for realistic colors in their photos? Stay tuned to Planetary Radio to find out. Dan Derda sure gets around. I mean that in both the physical sense and the intellectual one. Dr. Derda is a senior research scientist in the Department of Space Studies at the Southwest Research Institute. He probably knows as much about asteroids as anyone on Earth,

and that includes his knowledge of near-Earth objects, or NEOs. Dan, welcome to Planetary Radio. Hello, Matt. It's a pleasure to talk with you again. Yeah, and it is again. The last time we talked, we had a very specific topic, which certainly will come up this time, and that is the fact that you coordinate the Shoemaker-Neo grant program for the Planetary Society. Why don't you tell us what that is?

Oh, sure, yeah. The Gene Shoemaker Near-Earth Object grant program was started by the Planetary Society in 1997 to honor Gene Shoemaker, who was a planetary scientist who probably did more than anybody else early on to help pioneer our understanding of asteroid and comet impacts on the Earth. And the real goal, the intent of the Shoemaker NEO grant program is to increase the, basically help out the professional programs and help increase the rate of discovery and follow-up observations of the near-Earth objects that are passing near our planet. There's the big search programs, programs like Linear, Loneos, NEAT, SpaceWatch.

They're funded primarily by the U.S. government through NASA primarily, and they're doing a wonderful job. I mean, the estimates of the population of small asteroids and small fraction of burnt-out comets that are passing near the Earth, something like maybe 1,100 objects larger than a kilometer across, something like that, early on, about almost a decade ago, NASA established a goal to find 90% of those objects within a decade. And we've been doing pretty good. The professional surveys have now found probably on the order of, you know, 60% or so of the objects that we know should be out there,

and they're creeping up on that goal pretty quickly. But those professional programs are, you know, it takes a lot of money to run them, and by the time all that money is doled out from the government sources, there's not a whole lot left over for the professional astronomers to dedicate to the sort of follow-up observations and the physical studies observations of these objects. The primary goal of those surveys is to survey, to find the objects. And that's where the Planetary Society members, through their donations, can really help,

because through the Shoemaker Program, we've been funding a number of dedicated amateurs around the planet that are basically helping out the professionals in filling in the gaps where the professionals don't have the time or resources to be able to do it. As is so often in these programs that the Planetary Society gets behind, one of the parts that I love the most is this human side. The fact that the guys who get these grants, and I've talked to some of them, these are not guys who hang out at the Keck or get to use those instruments or telescopes that we all hear about, the ones that are hundreds of inches across.

They have smaller instruments, maybe at a college, and they desperately need a few bucks so they can buy a new CCD camera, and often that's where the grant has been able to help. Oh, immensely. The grants have helped immensely with people like that. And, you know, we say, you know, amateurs, amateur astronomers, but, you know, that's really, we don't mean that in a condescending sense at all. No.

I mean, quote-unquote amateurs are, they're doing professional quality work with pretty much, I'll have to tell you, a lot of these people I've talked to, and I've seen their, I've seen the facilities that they have built up, partially with Planetary Society help. I'll tell you, quite frankly, some of these quote-unquote amateurs have facilities and instrumentation that is making some of the professionals drool, quite frankly. The technology that they're able to put to use for the follow-up studies on NEOs is pretty impressive. And that's one of the great things that's happened in astronomy. I mean, sitting next to me here in my home studio is my little 8-inch telescope

with computerized go-to function. I don't have a camera for it, but, I mean, really, it's become much easier for people on a budget, shall we say, to do this kind of work. Oh, absolutely. And as I said, it's really helping out the professionals. When you talk to Brian Marsden at the Minor Planet Center, you very quickly gain an appreciation for the work, the really valuable work that the amateurs do in helping to track

and follow up the observations of these near-Earth objects. I mean, just one example, the observations that are made by the professionals, quite often they're so busy surveying the sky that once an object is observed, they don't really have the time to go back and, as we say, follow it up, look at it several nights later to measure its position so that we don't, in a sense, lose the object. You have to keep following an object to define a pretty precise orbit. The more follow-up observations that you have, the more observations you make of its precise position in the sky,

the far better you can track and predict its position in the future and therefore predict future Earth near encounters or even impacts. Yeah, whether it's a rock we need to worry about. Exactly, exactly. And that's exactly where the programs that are funded through the Shoemaker Grant Program really help out. These folks out there are helping with those follow-up observations. And not only the follow-up observations to help us understand where these objects will be in the future, but in a lot of cases the observations that are being made are helping us understand what these objects are,

the physical studies, how large the object is, how fast it's spinning. Is it oblong in shape, is it perhaps even a binary, for instance, does it have a little moon going around it? All of these sorts of observations are well within the capabilities of what's being funded through the Planetary Society, and they need to be done. What a great transition for me to be able to ask you why you shoot little aluminum balls at rocks. I have a program.

I've been working with a colleague of mine, George Flynn. We've been, for the last couple of years now, traveling out to NASA Ames Research Center using the Ames Vertical Gun Range. This is a very large gas gun, which is used to fire, shoot little aluminum pellets or steel pellets or glass pellets of various sizes at targets, rock targets, soil targets, things like that, to simulate the sort of impacts that happen in the solar system, either impacts of asteroids

onto planets or planetary surfaces, or the impact between asteroids or smaller debris in the asteroid belt. George and I have been working for a number of years to look at and study the actual disruption of real meteorite materials. There's a lot of the work that's been done in the past has been done on things like cement targets or terrestrial basalt samples, the sort of common familiar rocks that we're all used to dealing with and to kind of use those as analogs for the breakup of asteroids. And there hasn't been a whole lot of work done on using real asteroidal material, in other words, meteorites. And so George and I have been studying the breakup of those meteorites to look at the production of interplanetary dust particles out in space.

In that process, we're getting a lot of insights into how those real meteorites break up because meteorites have a whole bunch of different types of mineral grains in them. They have chondrules. Some of the most common meteorites have these little olivine-rich mineral blebs in them called chondrules. They're maybe a millimeter or so across. And the composition of the chondrules is a little different than the composition of the rest of the composition of the chondrules is a little different than the composition of the rest of the bulk of the meteorite.

And what we're trying to understand is, does that affect the way in which interplanetary dust particles are made? Do the dust particles come from certain parts of the meteorite and not others? And the best way to study that is to break up real meteorites. Dan, I'm going to use this opportunity maybe to go to a break. But when we come back, I want to talk to you about some of your friends in high places, specifically the ones who take you up in F-18 fighter jets. Great fun.

Dan Durda is our guest. He is a senior researcher at the Southwest Research Institute. Planetary Radio will be back right after this. 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. You can learn about these adventures and exciting new discoveries from space exploration in the Planetary Report. The Planetary Report is the Society's full-color magazine. It's just one of many member benefits. You can learn more by calling 1-877-PLANETS. That's toll-free, 1-877-752-6387. And you can catch up on space exploration news and developments

at our exciting and informative website, planetarysociety.org. The Planetary Society, exploring new worlds. Matt Kaplan back with Planetary Radio and our guest Dan Derda, who, among other things, is the coordinator of the Gene Shoemaker NEO grant program at the Planetary Society, but does lots of his own research at the Southwest Research Institute, gets them around, and also gets them up high in the sky. You really have a good time in those F-18s, right? It's not just science, is it?

It's science, but boy, I have have to admit it is a heck of a fun way to do astronomy what are you doing up there well for a couple years now i've been working with my colleague alan stern starting around 1998 when i first uh first started working at the southwest research institute we uh were developing um a the concept to be able to do uh high altitude airborne astronomy from smaller, higher-performance aircraft than astronomy has conventionally been done in the past. NASA has flown airborne astronomy missions in the past. We had the Kuiper Airborne Observatory coming up.

Now we're going to have the SOFIA aircraft that converted at 747. Alan's idea back in the late 1990s was to bring this to smaller aircraft that you could deploy a little bit more flexibly and a little bit higher performance aircraft to give you a little bit more opportunity to get up higher, get up faster, and do these sorts of things. We were starting out with looking at asteroid occultations. It's when an asteroid, as they move through the sky on their orbits, they'll occasionally pass in front of and eclipse background stars. And if you're lucky enough

to be in just the right position at just the right time, when the shadow of that asteroid being cast by the star sweeps over the surface of the Earth, you'll see the star wink out temporarily and back on. And that's a great opportunity because we know the orbits of the asteroids pretty well to measure their sizes. You can time how long the stars blinked on and off, and knowing the speed of the asteroid, that kind of gives you a chord across the asteroid, tells you how big it is. That's great if you happen to be in just the right place with your telescope, but if that event happens out over the water, over the ocean, or if it's cloudy that particular night, which often seems to happen with these important events, you miss the event.

With an aircraft, you can fly out over the water or above the clouds and make sure you don't miss it. How do you fit any kind of useful instrumentation into what's basically a fairly small airplane? It's not a large aircraft, and it helps certainly being a small astronomer. I'm not that big a person. The materials, the instrumentation, I should say, that we carry is pretty small. Our system is centered around a very sensitive image-intensified CCD camera that actually frames at video rate. It's essentially a very intensified video camera.

And we put a standard, although relatively expensive, very high quality, but a pretty standard Nikon camera lens on the camera. There are some small boxes that power the camera and take the data to and from the camera. We have a small camcorder that we record on, a GPS unit, and so on and so forth. It all does actually fit within the rear cockpit of the F-18, although, of course, you do want to be safe with it because this is an aircraft that, if by chance things happen to go wrong, which they occasionally will in some aircraft, you may have to eject out of the aircraft. You want to make sure that none of this gear gets tangled up with you as you may have to eject. So we have to go through some safety procedures to make sure that everything's clear and out of the way.

But it does work well, and we've worked with NASA's Dryden Flight Research Center to develop that program. And they've been absolutely wonderful, and the program just would not have happened without their help. Well, so I take it you picked up some useful data. Oh, we absolutely did. We timed a beautiful occultation of an asteroid called Palixo back in 2000. And since then, of course, with that program demonstrating how well that system really works, we went on to now start to search for volcanoids,

which are a population of very small asteroids which may be orbiting the sun very, very close to the sun, actually inside the orbit of Mercury. But since they're so close to the sun, it's a very hard thing to do from the surface of the Earth to look for these things because you're looking in the bright twilight real close to the sun. If you can get up real high, very high up in the atmosphere, so that most of the atmosphere, in fact, is below you, you can make the sky dark enough that it makes it a little bit easier to look close to the sun. So we've been working with our airborne system to revive these searches for volcanoids.

Yeah, and I'm glad you brought that up, because I was going to. These are a fairly new, certainly not an area that I've been familiar with. In fact, the term volcanoid itself is rather fascinating. How did it get that name? Well, it's not related to Mr I've been familiar with. In fact, the term vulcanoid itself is rather fascinating. How did it get that name? Well, it's not related to Mr. Spock, actually. It's a little different. It's about a century-old problem, quite frankly. Back, well, turn of last century, right?

Astronomers had been very precisely measuring the motion of the planet Mercury and noted that the position of Mercury's, the close point, the perihelion point of Mercury's orbit around the sun, where it's closest to the sun, that point migrates around the sky over time. And you can account for that by the gravity of the other planets tugging and pulling on Mercury and so on. And astronomers had accounted for all of the tugs and pulls they could,

but still couldn't quite account for some of Mercury's motion. And they thought perhaps there might be an as-yet-undiscovered small planet orbiting the sun even closer to the sun than Mercury. And they called it Vulcan after the Greek god of fire and metallurgy, it kind of makes sense. Well, they didn't find that planet, and right around the time that the searches for this hypothetical planet Vulcan were peaking up, Albert Einstein came along with his new theory of gravitation

that because of the curvature of space-time near the sun completely accounted for all of the motions of Mercury. And so the whole reason for searching for a planet Vulcan sort of went away. But what didn't go away was the idea that, well, you know, there still may have been debris left over from the formation of the planets in stable orbits close to the sun. It's dynamically possible. And so people continue to search for little, little Vulcans, the Vulcanoids. And that search has gone on.

But as I said, it's a very difficult search. And so up until now, nothing has been found. But that's because the searches have not been very constraining. And so we're trying to do, we're not giving up. We're trying to do the very best job we can. With a couple of minutes left, let's turn from out there in space and the stratosphere to caves in Arizona, in fact, water-filled caves. You've spent some time in these. I've spent a lot of time in some caves in Arizona and also in Florida when I was a graduate

student there in Florida. I'm not sure that you draw a sharp line between the fun stuff you do on the job and the fun stuff you do for fun. Well, I'm a very lucky person. The things I consider fun are the things that are really sort of part of my job, too. It's a very great position to be in to love what you do so much that it's just your hobby anyway. So I'm very lucky in that regard. Cave diving has, up until now, actually been one of the hobbies.

But quite frankly, it's turning into a position where I may actually be able to do some of it as part of my research. I've been proposing to work on developing and designing a fully autonomous underwater robot that can go down deep into thermal springs, thermal hot springs, and map the systems down there and search for microorganisms that we've not been able to detect from the surface because it's hard to get instruments down there. So we're going to build this vehicle. We're trying to build this vehicle.

It'll be a great technology for astrobiological research. Of course, somebody has to dive with it, so I might get to do some cave diving as part of my research. I can think of a certain Jovian moon that you might want to send that to. Yeah, that's exactly what we're interested in. The moon Europa may have a pretty deep subsurface ocean under that crust of ice, and at the bottom of that ocean may be possibly thermal vents and so on,

much like the deep ocean vents on the Earth where we found unexpected forms of life. And so we are, in fact, developing this vehicle just for the future application on Europa. Dan, we're almost out of time. There was one more topic that's a bit difficult to capture on the radio, but we will give people a way to view some of the amazing paintings, the artwork that you do. You have this in common with a colleague of yours who was previously on our show.

Yes, in fact, Bill Hartman was just interviewed for your show a few shows back. And Bill and I are members of the International Association of Astronomical Artists. We're a group of, oh, a very diverse group of people, some scientists, some artists, some computer engineers. We have one guy who worked in India're a group of, oh, a very diverse group of people, some scientists, some artists, some computer engineers. We have one guy who worked in India as a pit car, a pit crew chief. These are very versatile, very nice people who are also extraordinary artists, and it's an honor for me to be considered part of their group. It's a great amount of

fun. I enjoy painting. It's a fun pastime, and because of my interest, I tend to paint astronomical subjects, and so people have probably seen a few of my paintings out there. The painting for the New Horizons mission to Pluto, which the Planetary Society played a very active role in making sure it happened.

That's my painting that people see out there quite a bit. It's a great amount of fun. Your work is outstanding. People should take a look at it. And we will provide some web links to your personal homepage at the Southwest Research Institute. We'll give the main web address for the SWRI right now, and that is www.boulder.swri.edu And if any of our listeners didn't quite manage to get that down with their pencil, just go to the website, planetary.org.

You may already be there listening to this show. You'll find several links that will tell you about SWRI. We'll have one to that International Association of Astronomical Artists and to Dan Durda's homepage, and you can see some of his own artwork there. Dan, we're out of time. Thank you very much, and I look forward to talking to you again here on Planetary Radio. Thanks, Matt. It was a pleasure talking with you.

We'll be back with Q&A. Why do different scientific photographs of the same planet look differently colored? Planetary images are often taken in colors that the human eye actually cannot detect. Multiple images taken through infrared, visible light, or ultraviolet filters are combined in a standard red-green-blue format to show features we ordinarily couldn't see. Sometimes an attempt is made to approach the natural colors of objects, but more often, contrast is deliberately enhanced to bring out subtle details. One image can even be subtracted from or divided by another

to expose color differences so subtle that they can't be detected by any other image enhancement method. This way of looking at data can be a powerful way of seeing, at a glance, phenomena that would be difficult to describe in other ways. Got a question about the universe? Send it to us at planetaryradio at planetary.org. Be sure to provide your name and how to pronounce it and tell us where you're from. And now, here's Matt with more Planetary Radio.

It's time for What's Up with Bruce Betts of the Planetary Society, Director of Projects. Bruce, welcome back. Thank you very much. It's spiffy to be here. And what do we start with? What's up in the sky? Well, we've got five planets, our naked eye friends, but they're getting hard to find, some of them. But not Jupiter. Jupiter, really bright in the evening in the west, and in the morning, Mars is dominating in the southeast, getting much brighter, much faster, as Mars and Earth get closer and closer together.

You still can see Mercury and Venus very low in the east-northeast if you look just before dawn, and you can see Saturn low in the west-northwest in the evening. I guess it's okay for us to mention again, we haven't done it in a while, that the big time with Mars is coming, but it's getting better all the time? Getting better all the time, and August 27th it will be closer than it has been in 73,000 years to Earth. But even right now and during this month, you can watch it brighten, going from bright to basically the equivalent of the brightest star in the sky by the end of the month. And I heard just recently that the best place on Earth to be,

if you really want to be as close as possible, is Tahiti on that August 27th? It is indeed on that moment that Earth and Mars are truly at their closest possible point. Tahiti is roughly where the sub-Mars point is on Earth. You could literally go to the highest point on Tahiti and just almost reach if you just stretch a little. Oh, well, anyway, no. But even if you don't go to Tahiti, or even if you do,

you'll have great views of Mars already and coming up and getting better and better. And we'll give you more information as we get closer to that event. Lots of other stuff and other events that will be here on Earth that we'll be able to talk to people about that they might be able to participate in. Yes. What else have we got? This week in space history, June 3, 1965, Gemini 4 was launched,

and Ed White takes the first U.S. spacewalk. Ed White. Great guy who later, of course, we lost in the loss of Apollo 1. Right. Let's go on to... Random Space Fact! On average, the distance from Pluto to the sun is approximately 40 times the distance from the Earth to the sun. So if you think about it in a different way, if a scale model were constructed with the sun on the California coast

and the Earth about 75 miles inland, then on the same scale, Pluto would be in New York. Wow. That's great. I love those. It's really far away. But I love those little, you know, if the sun was a grape. We'll come back with sun with grape stories. If we make the sun a grape, then we're not going to be able to see any of the other planets. Are we going on to trivia? Yes, we are.

We are. Before we get too far into fruit, let's go on to trivia. Last week's question was about planetary nomenclature. Picking randomly, Saturn to Moon Tethys. What are features on Tethys named after, named for? Every planet and moon in the solar system has different conventions for what to name features after. What about Tethys? Well, it turns out the answer is people and places from Homer's Odyssey, a literary reference.

How'd those people do? They did their typically great job. Way to go, people. We had only one incorrect answer. It was way off. A good guess, but someone who didn't actually check. But boy, people just did a terrific job. And are you ready for our winner?

I am indeed. He is Brian Gray. Brian Gray of Minerva, Ohio said the names of locations on Tethys are taken from Homer's Odyssey. So we congratulate Brian. He'll be getting that Mars 3D poster that we send out in the mail to these lucky winners. Congratulations. And if you'd like to try to win a Mars 3D poster this coming week, answer the following question. And this time, just to challenge you a little bit, we're going to ask you for two related

answers. The question being, what was the first successful mission to fly by Venus, and how many missions had tried unsuccessfully to reach Venus before then? So first mission to actually get there, and how many missions were tried by any country? A little hint for our radio listeners, I suppose those who just dropped by the website and see the trivia question, you can find the answer on our website, planetary.org, somewhere in the Learning Center.

We're being kind this week because this is a little bit tougher. I mean, it's the first sort of two-part answer you've asked for, I think. But it's there if you want to find it, planetary.org. You may already be listening on the website. If you're listening on KUCI,

that's where you can find this week's answer and a whole bunch of other great stuff. How do people enter, Bruce? Go to planetary.org, follow the links to Planetary Radio, and it will tell you how to enter. We're done. We've got an extra minute. I mean, how in the world are we going to fill this? Oh, well, I'd like

to give people some information about a recent workshop that the Planetary Society hosted along with the American Astronautical Society and the Association of Space Explorers on what to do next in space transportation. You can find the results of that on our website, among other recommendations of these many experts, was to essentially develop new launch vehicles to send humans to space. So if you want to see those results, go to planetary.org and follow the headline for that. And with that, I'll also just say look up in the night sky and think about ice cream with chocolate sauce.

Sounds good to me. Anything from you, Matt? No, I'll just say that's Bruce Betts, the director of projects for the Planetary Society, who joins us each week here for What's Up. Join us for next week's Planetary Radio Show when we talk with Dr. Wes Huntress, former Associate Director of NASA and now President of the Planetary Society.

Have a great week.