Planetary Radio: Space Exploration, Astronomy and Science - The Sloan Digital Sky Survey Captures the Universe

Episode Date: March 21, 2011

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Surveying the Universe in unprecedented detail, this week on Planetary Radio. Welcome to Public Radio's travel show that takes you to the final frontier. I'm Matt Kaplan of the Planetary Society. There is a telescope and camera that have patiently, methodically photographed the sky for many years. The result has been a single awe-inspiring image with more than a trillion pixels, along with data that will serve as a reference for many years to come. Now the Sloan Digital Sky Survey is taking the next giant leap into our universe.

We'll talk about all this with the survey's scientific spokesperson, Bob Nickel. Everybody else on the show today will have nice things to say about MESSENGER, the spacecraft that has just gone into orbit around Mercury. But Bill Nye will also tell us how the corrosive skies of Venus may have raised a caution flag for our own world. And Bruce Betts will tell us where to look for a little Mercury in the night sky. That'll be on What's Up. First up, though, is Emily Lakdawalla, the Planetary Society's Science and Technology Coordinator and its celebrated blogger.

Emily, no question what the big story was last week, and that was out at Mercury. That was very exciting. You know, I was really nervous, I think mostly because of Akatsuki's recent failure to enter orbit, and also because one of my grad school office mates, Louise Proctor, is the head of the imaging team on that mission. So I was really, really nervous for her. And I'm so happy that everything went well. We now have a spacecraft in orbit at Mercury, ready to start its science mission. That means we now have spacecraft actively orbiting the Sun, Mercury, Venus, Earth, the Moon, Mars, and Jupiter. And they're, I mean, I'm sorry, not Jupiter, but Saturn. And they're on their way to Vesta and

comet Churyumov-Gerasimenko. There's orbiters everywhere, and it's very exciting. And you actually pointed out that we now have orbited all of the classical planets. I can't claim to have noticed this. Somebody on unmannedspaceflight.com noted it. But yes, all of the naked eye planets have now been orbited by spacecraft. So that's a key milestone, I think. I'm also happy to mention that next week, Sean Solomon will be back on the program. He is the principal investigator for the Messenger mission.

And so we will have a chance to congratulate him directly. As you were waiting for word that Messenger had successfully gone into orbit, you put together yet another really poster quality image. Well, of course, the quality of the images is a result of the amazing processing done mostly by Ted Strike. But, yeah, I decided to point out to people that Mercury is a very small planet. It's actually smaller than the solar system's two largest moons, Ganymede and Titan. And it's comparable in size to all the rest of the Galilean satellites, just a bit larger than our moon. So, you know, there's a whole bunch of bodies in the solar system. They're all roughly

similar in size. And it's interesting to line them up and look at them all together. You took a little bit of heat from some folks. Ted came to your defense because you didn't include Pluto, but for very good reason. Well, the main reason that I didn't stick Pluto in there is, of course, we have no photo of Pluto yet. That's New Horizons' job. But even if I had, it would have been smaller than all eight of the bodies I showed there. The very smallest one was Triton at 2,700 kilometers across, and it was much smaller than the other seven. Pluto is even smaller than Triton, only 2,300 kilometers across. So it's actually not

that big a body, although it stands tall in the outer solar system. Well, it is a beautiful compilation. You'll find it. It's one of the March 17 entries in the Planetary Society blog from Emily. And I guess that's it for this week. Thanks, Emily. All right. See you next week. Emily Lachtwal is the Science and Technology Coordinator for the Planetary Society blog from Emily. And I guess that's it for this week. Thanks, Emily. All right. See you next week. Emily Lachtwal is the science and technology coordinator for the Planetary Society and a contributing editor to Sky and Telescope magazine. I'll be right back after we hear from Bill Nye. Hey, hey, Bill Nye, the planetary guy.

And this week, I want to congratulate the messenger team for getting that spacecraft in orbit around the innermost planet, Mercury. Very exciting. Who knows what they'll discover? They'll see parts of the surface that we've never seen. It's going to be an exciting future. Now, as you move away from the sun, we come to Venus. So here's the deal.

When a volcano erupts on Earth, especially in the tropics, it sends all this sulfur dioxide up into the sky, and it reflects sunlight back into space. So the world cools off a little bit. Well, on Venus, there's sulfur dioxide, and you'd expect it to reflect sunlight into space. But no, it doesn't. It turns to sulfuric acid, which in turn turns to vapor, and that's transparent. The sunlight goes right through it. There is no reflecting into space. So this trick that some people have come up with to put sulfur dioxide in the Earth's sky is probably not so well informed. Now, we made this discovery on Earth by studying another planet, Venus. That's pretty cool, and I hope it's not going to be pretty hot. So just as Carl Sagan

said back in the day, comparative planetology is a vital thing for humans to pursue. Now meanwhile, our hearts go out to the people in Japan who are dealing with the earthquake, the subsequent tidal wave or tsunami, and now this very troubled, exploding, burning, hard to cool off reactor or set of reactors. If we try to use nuclear power to address climate change, because nominally it doesn't produce any greenhouse gases, this may not be such a good idea. I mean, the reactor is nothing but trouble. And then furthermore, to address that problem, let's not go shooting sulfur dioxide into the sky because that apparently has its problem of its own. We're going to have to come up with something else.

We can, and we'll be able to do it because we have learned as much about the worlds around us as we can. Well, good luck to people in Japan. I hope we can resolve this reactor issue as quickly as possible. Thank you to the Messenger team for doing such a great job. And thank you to the Venus Express spacecraft, which allowed us to make this discovery on Venus. It's an exciting time in science. It's a remarkable time in history. Our world is changing.

Let's study the worlds around us to help us address that. I've got to fly. Bill Nye, the Planetary Guy. Let's say you're an astronomer who wants to study quasars, or perhaps a particular kind of galaxy. How will you know where to go in the sky to find your objects of desire? You need a map, but not just a map. You'll also want a database that tells you the nature of every object on that map. The Palomar Sky Survey that began in the 1940s relied on old-fashioned photographic plates. Digital cameras, like the one you take on vacation, use a far more sensitive

technology. More sensitivity means more objects to see in any given patch of sky. So a new survey was begun in 1998, working with a gigantic CCD camera attached to a telescope in New Mexico. Now, this advanced survey has released a breathtaking composite image. You'd need more than 500,000 high-def TVs to reveal all the detail it contains. Last week I called up Bob Nickel to learn more. Bob is a professor of astrophysics at the University of Portsmouth in the United Kingdom. He also serves as scientific spokesperson for the international survey that has entered its third phase. I hear you're just back from a football match. I hope your team won.

I didn't, unfortunately, but this is soccer for you guys over there. Absolutely, yes. But we can celebrate something else, and that is your involvement with the Sloan Digital Sky Survey. My interest in talking to you about this came out of a press release, came out a couple of months ago now, and that was really trumpeting the release of this incredible image, a terapixel image, over a trillion pixels. There is so much more to talk about in the survey story, but that's pretty significant in itself. How long did it take to build up this image of, in essence, the universe? Well, the camera started taking the data, and the camera itself is a 126 megapixel camera. So it's a pretty big thing. It's not like you can buy this thing at Best Buy.

So it started in the year 2000, and basically it's been running for about 10 years. So you can think of the Sloan Digital Sky Survey, at least a part of it, as the world's biggest digital camera. It does something called drift scanning, and I don't really want to get into what that is, but that's a very efficient way of observing the sky. And effectively, over the last 10 years, when the sky's been clear and there's no clouds

and those pristine nights that you know when you go out and look at the stars. The Sloan is scanning the sky. And what we've done, a bit like the software you can get now for your personal computer, we stitched together all the separate images of the sky. And after 10 years, and that's what we announced that the American Astronomical Society meeting in January after 10 years we made this terapixel image it's only a third of the sky so it's not the whole sky and ironically when you look at the amount of the universe that it encompasses,

it's actually relatively small. Although it sounds fantastic, we still have a lot more of the universe to look at and to catalog. Sounds both fantastic and pretty exciting. But even within this image, is there any way to estimate how many objects, stars, galaxies, and otherwise are captured in this picture? Oh, we've done that. Absolutely.

In fact, we know that pretty exactly. I can't remember the number off the top of my head. But I can tell you it's somewhere in the region approaching 500 million objects have been detected. Wow. And those are stars, galaxies, some of them are asteroids, some of them are supernovae in there as well. So we've catalogued all those and we released that as well along with the image. So really you can think of this as sort of a photograph, the digital photograph of the night sky,

and then if you want you can download the spreadsheet of the night sky, which will tell you all the objects that are in that image. And both of those were released back in January. And I would like to say they've been released not just for the professional astronomer, those guys love working with our data, but it's out there for the public as well. And there are projects which take our data and turn it into useful products that the public can look at and interact with. Google Sky that uses the Sloan Digital Sky Survey data. And there's also this project called Galaxy Zoo, which uses our images of galaxies and asks the public to sort of classify them and gives us information about it.

So it's not just professionals that get something out of it. The public really do interact with these sorts of images. And I guess that has been an important part of the philosophy, the thinking behind the survey right from the start. It has. I think that ethos has grown up through the survey. Certainly at the beginning, we were certainly asked and wanted to release the data in a regular fashion. And in January, we had what's called Data Release 8. It was the final data release of Sloan 2.

But we've had eight releases over the last 10 years, so basically one a year. And that has become sort of the norm in astronomy. In fact, in astronomy, people regularly give their data away. And there's something wonderful about that because it stimulates scientific investigation, it stimulates the public to get involved, and there is something very noble about the fact that our data is actually worthless.

And I mean that in a good way, in that, you know, we can publish it, and it doesn't matter if someone else finds something exciting in the data, because it's not like some big multinational company is going to be scooped on this. It really is sort of for human knowledge that we take these images of the sky, and then we give them back to the public to look at. And I couldn't agree more with you with that approach. And I'm glad that you mentioned the Galaxy Zoo, and I guess a part of that being the Zooniverse project, which is giving folks who may not even own a telescope a chance to participate in the exploration of our galaxy and universe.

I joined the Galaxy Zoo relatively early on. It was still a project that was being formed. And I remember in the early days, we were a bunch of astronomers were sat around saying, well, why don't we get everybody to look at our data for us and tell us what it looks like?

And it seemed like a really good idea at the time. And I remember us doing the back of the envelope calculation and saying, well, it'll probably take about three or four years and that's okay because you know you know we've got a few years to wait around and so we were fully expecting for us to be still waiting for the results today we were blown away by the response. The numbers are phenomenal. Effectively, Galaxy Zoo had a quarter of a million users, and they've done about 60 million classifications.

And we finished the original Galaxy Zoo in only a few months. And now, as you point out, we're now in many different types of zoo. We've got the Hubble Zoo. We've got Galaxy Zoo 2. There's Moon Zoo. There was Supernova Zoo. And this whole zooniverse of public interaction with these data really has caught us by surprise. And what I find the most interesting about it is not just that the data is very useful for us,

but when we've asked people why they want to do this, is very useful for us. But when we've asked people why they want to do this, what's incredible is that their overriding response is they want to feel part of the scientific process. And I think we've tapped into something

that I don't think people have really appreciated before, that the general public has a desire to do science. Now, they might not be able to do it as a professional because, you know, they've got other jobs to do it as a professional, because, you know, they've got other jobs to do,

and they probably earn more money doing those other jobs. But anyway, we'll get back to that later. There seems to be a deep-seated desire in people to be involved in this empirical scientific endeavor. And that, I think, is the most rewarding part

of being involved in the galaxy zoo. No question. And we began to discover that at the Planetary Society when we became involved years ago with the SETI at Home project, the folks at UC Berkeley. And it seems very clear that people not only love science, but they want to help do science. We'll hear more from Bob Nickel about the Sloan Digital Sky Survey in a minute. This is Planetary Radio. I'm Sally Ride. After becoming the first American woman in space, I dedicated myself to supporting space exploration and the education and inspiration of our youth. That's why I formed Sally Ride Science, and that's why I support the Planetary Society. The Society works with space agencies

around the world and gets people directly involved with real space missions. It takes a lot to create exciting projects like the first solar sail, informative publications like an award-winning magazine, and many other outreach efforts like this radio show. Help make space exploration and inspiration happen. Here's how you can join 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. 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. The Sloan Digital Sky Survey, or SDSS, has already assembled millions of images into the most detailed sky map ever created. Yet its work is far from finished. That's according to Bob Nickel, scientific spokesperson for this vast project

that involves more than 25 international partners. Bob is a professor of astrophysics at the University of Portsmouth. Let's talk about the rest of the survey, because really, that amazing image is just the start. There are four big projects behind this, all of them based on the use of pretty advanced spectroscopy? That's correct. In fact, this data release 8 of the Sloan that we had in January was both the end and effectively the start. It was the end of 10 years of the original Sloan survey, and the camera that has made that fantastic image has now been retired. But Sloan 3, which is the new version of the Sloan Digital Sky Survey, is now focused solely on measuring the colors of objects in that image. So what we do is we use fiber optics to capture the light from millions of those objects

in that image, and we disperse that light so that we get a spectrum for it, so we can look at the colors of all the objects. And that's vital if you want to measure the distance to those objects. And so what Sloan 3 has become is a spectroscopic survey, and it is looking for distant galaxies to understand what has made up the universe. It's looking for distant stars in our own galaxy to measure the dynamics of our galaxy. And then more exciting for some, it's looking at tens of thousands of nearby stars, looking for the slight wobbles in those stars due to heavy planets going around them. So Sloan 3 is, at the moment, looking both for planets, it's looking for stars in our galaxy,

and it's looking for some of the most distant galaxies in our universe. So it's really doing the full gamut of astronomy that you can do with a single telescope. I also read on the website, which we will link to from our page for this radio show, So it's really doing the full gamut of astronomy that you can do with a single telescope. I also read on the website, which we will link to from our page for this radio show, but anybody can reach by Googling or whatevering in your favorite search engine, Sloan Digital Sky Survey, the project may help us, if not to identify dark energy, at least to characterize it a little bit better. Yes. We're in a very strange situation in cosmology. In cosmology, the last decade has produced some phenomenal surprises and has produced a model for the universe that works incredibly well.

We can make predictions about the universe from this model, but ironically, we don't actually understand the constituents of the model. So it's like driving a car without actually understanding why the car actually works. The irony is, is that right now we know there's this dark energy out there. We don't know what it is. The only thing we know about it is that it makes up about three-quarters the energy density of the universe. So it's the most stuff out there in the universe. Now, what we don't know about it is anything else. We don't know if it clusters. We don't know if it varies with time.

We don't know if it clusters. We don't know if it varies with time. We don't know if it varies with space. We don't know if it links with other components of the universe. So what Sloan 3 will do is it will start that process, and I suspect the process will take a few decades, unfortunately, but it will start the process of pulling back the layers of the onion to get closer to what the properties of this dark energy is. And one of the key things that Sloan 3 should produce is a definitive answer about whether this changes as a function of time in the universe. So is the dark energy this famous constant that Einstein came up

with many, many years ago, or does it vary? And I think that's a fundamental question we need to know about this dark energy, and Sloan 3 should hopefully give us one of the first looks at that question. Bob, it has been delightful. I am terribly sorry to say that we're out of time, but perhaps we can check back the next time the Sloan Digital Sky Survey has a major release of data. Well, please do, and let me assure you that there's lots of results on the horizon, and I think you'll hear a lot more about Sloan 3 in the years to come. We'll keep tracking. Thank you. Bob Nickell is the scientific spokesperson for the Sloan Digital Sky Survey 3. He is also a professor of astrophysics at the University of Portsmouth in the United Kingdom,

where he directs the Institute of Cosmology and Gravitation. We'll be back with yet another astronomer. That'll be our own Bruce Betts for this week's edition of What's Up in just a few moments. It actually happened. I made it into the office where I'm sitting in the office of Bruce Betts, the Director of Projects for the Planetary Society, where we're about to

tell you what's up in the night sky and give away some other cool stuff. Hi. Hey. Glad you made it through security. Yeah, me too. It's getting really tight around here. What's that all about?

Well, mostly we left pictures of you, so you weren't supposed to get through security, but I didn't know you'd wear a disguise. So now I can't go here or the post office. And yet, ironically, they have your picture all over the post office. All right. Stop wasting time. Sorry. You started it.

No, maybe I should. Anyway, night sky. Check out Jupiter. It's getting lower and lower, but Jupiter over in the west, shortly after sunset, bright star-like object. You might still catch a little Mercury, a little brighter object farther down, but also dropping out of the way. Saturn, on the other hand, just getting easier and easier to see,

up in the early evening in the east, looking yellowish, high overhead in the middle of the night, and Venus still super bright in the pre-dawn sky. All right, we move on to this week in space history. It was in 2001 that the Soviet, later Russian, space station Mir re-entered the atmosphere. Ten years ago this week. We also had comet Hyukutaki closest approach to Earth 15 years ago this week. Was the Mir re-entry, was that one of those that Taco Bell tried to get some mileage out of? I don't recall. I don know and they're not paying us so the heck with them

we move on to our next segment which since you're actually here with the microphone we'll do this random space fact that was neat that was neat you've never done that before i try to be different but it's hard well it's been eight and a half years. Really? Wow, we're old. Okay, we just had Messenger. Congratulations, Messenger, on successfully orbiting the planet Mercury, first Mercury orbiter. I'm fired up about that, by the way. I've been waiting for that my whole life. Just seems that way because it's been up there a long time.

No, I mean to have a Mercury orbiter, not for Messenger. Oh, I get it. Well, as Emily pointed out, last of the classical planets to get an orbiter. Indeed it is. It deserved one. Poor little Mercury. But now it's got one. So when did the other orbiters occur? When was the first orbiter of Earth? Sputnik 1 in 1957. Moon, 1966. Mars, 71. Venus, 75. Jupiter, 95. The asteroid Eros in 2000. Saturn in 2004. Asteroid Itokawa in 2005.

And now, finally, 2011, Mercury with Messenger. And Sean Solomon, the PI for that mission, will be our guest on the show again next week. Very cool. I mean, they're neat because they've been doing such great science. They've given us the mystery half of Mercury on their three flybys, but now they get to party in orbit. So good. I'll look forward to that show. We move on to the trivia question. I asked you, what is the kind of airplane that space shuttle pilots use to practice since they can't just throw an orbiter up there whenever they want to. What airplane do they use in their practice?

How do we do? Huge response. I suspect because we are giving away again Livio Radio's Carmen car audio player. This is the neat little unit that comes with software, makes it real easy on a Mac or a PC to download the podcast of your choice. You take the thing out to your car, plug it in the formerly known as a cigarette lighter, and it's got a little FM transmitter and you listen to your podcast. So a pretty cool thing without needing any other hardware. Really just two answers, both correct. I think you know what they are. Indeed, a Gulfstream II is the type of

aircraft and then they've modified it. So they also give it the title C11, correct? Yeah, some people said C11, some said C11A, but either one would have been close enough. Our winner, Ron Basque of Milford, Connecticut, a first-time winner as far as I could tell. He just mentioned, yes, a Grumman Gulfstream 2. He even gave us the tail numbers and added this little fact that because the actual characteristics, if they were to set down on the runway, would have been quite different from the shuttle. They actually only went down to about 20 feet. And then they said, okay, you did good. You're ready to fly the real thing. Yeah, well, it's the last 20. You can just drop that part. But actually, the space shuttle

as many people may not be aware, has the gliding characteristics pretty much of a rock. So even with the Gulfstream 2, they have to do really weird stuff to it. They put the flaps down, they leave the gear down, and they actually throw their engines in reverse in order to make them drop like a rock. It sounds like I'm making this up, but I'm not. Yeah, Anders Brolin, our listener in Sweden, one of our listeners in Sweden, was on to this because he said indeed they modify the Gulfstream for a high drag configuration. But he then went on to say, I guess that means the plane is fully

dressed up in skirts with makeup and a push-up bra. Which would add a lot of drag, you've got to admit. Yeah, I'll just leave that one. Well, anyway, we're going to send Ron Bass that Carmen from Livio Radio. It just makes quite an image as they're coming down. That's the reason. It's the airport that won't let them touch the ground. Anyway, we move on.

For this week, going back to the history of orbiters. 1971 Mariner 9, the first orbiter around Mars. What was the second? Go to planetary.org slash radio. Find out how to enter. You have until March 28th. That would be the 28th, Monday at 2 p.m. Pacific time to get us that answer. I think for a change, we're just going to give away a

Planetary Radio t-shirt. How's that? It's the greatest gift in the history of the universe. I'm glad you said it because it would have sounded so, you know, immodest if I had. Oh, exactly. Yeah. No, it's much better when I said. All right, everybody, go out there, look up in the night sky and think about if you had a flag to represent yourself, what would that flag look like? Thank you and good night. Maybe your flag would look just like the Mars flag that we're giving away on next week's show. He's Bruce Betts, the Director of Projects for the Planetary Society, and he joins us every week here for What's Up. Next week, Sean Solomon of the Messenger mission, now orbiting Mercury.

Then in two weeks, bad astronomer Phil Plait. 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.