Planetary Radio: Space Exploration, Astronomy and Science - Move Over Hubble: The Spitzer Space Telescope

Episode Date: June 13, 2005

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Hubble's infrared sister in the sky, 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. If anything, the Spitzer Space Telescope is a bit more of a miracle than the Hubble Space Telescope, and it is proving its scientific value on what seems like a daily basis. We'll talk with B. Thomas

Sofer, director of the Spitzer Science Center, about this amazing instrument. Later today, Bruce Betts is positively quillish over this week's space trivia contest. But wait, there's more, beginning with these space headlines. Okay, remember last week's show in which I reported that Mars rover Opportunity would be roving again within a few weeks?

I should have said hours. After spending more than a month stuck in a Martian sand trap, the little explorer is once again doing what it does best. Get the details at planetary.org. Cosmos 1, the solar sail, has been mounted atop the Volna rocket that will boost it into Earth orbit June 21st. All that remains to be done is to install the rocket in a Russian Navy submarine and put to sea. You can check out the new solar sail section on the web at planetary.org. We'll also be providing special coverage of the mission

over the next two editions of Planetary Radio. And Deep Impact is hurtling toward that spectacular 4th of July fireworks show in space. We're going to try to devote our show that week to this comet smackdown mission. In the meantime, there's an update at, you guessed it, planetary.org. Tom Sofer is up in a minute, right after Emily Lakdawalla examines a colorful mystery on Saturn. Stay tuned, space cadets. Hi, I'm Emily Lakdawalla with questions and answers.

A listener asked, In Cassini images of Saturn, the northern hemisphere is blue while the southern hemisphere is not. Why is that? True color images of Saturn from Cassini show a yellow-orange colored globe to the south of the rings, as we typically expect for Saturn. But north of the rings, you can see a blue-colored sliver, making Saturn's northern regions look a lot like Uranus or Neptune. The yellow colors in the south are caused by light reflecting off of high-altitude clouds.

In the northern hemisphere, there appear to be few clouds. As a result, sunlight penetrates more deeply into Saturn's sky there. Only the shorter wavelength blue light is scattered back to Cassini's optics. But why is it that there are few clouds in Saturn's northern hemisphere compared to the south? Stay tuned to Planetary Radio to find out. For thousands of years, humans looked to the sky in the only way they could, with unassisted eyesight. And when that clever Florentine fellow first turned a telescope to the heavens, he was still confined to the tiny portion of the electromagnetic spectrum we call visible light. But the universe had undiscovered secrets waiting for us,

secrets that would only be seen when we quite literally learn to look beyond our eyes, at radio waves, X and gamma rays, ultraviolet, and the infrared. B. Thomas Sofer's remarkable history has brought him from the infancy of infrared astronomy to the advent of the Spitzer Space Telescope, now following planet Earth as it orbits the sun. The Caltech Professor of Physics directs the Spitzer Science Center, operator of the Spitzer Space Telescope, named after renowned 20th century astrophysicist Lyman Spitzer, Jr. Tom Sofer, I want to start our discussion of the Spitzer Space Telescope with an image

that just blew me away, was just breathtaking. And that was the Sombrero Galaxy, I guess something that the Spitzer only fairly recently imaged? That's correct. It was part of a program that one of our legacy science teams is executing, imaging and spectroscopy of a variety of nearby galaxies. Absolutely beautiful. And really what I thought at the time was George Lucas, eat your heart out. It was that kind of a breathtaking image.

And it was, as I guess all the images are from the Spitzer, in false color. I suppose all the images have from spitzer have to be since they're working in the infrared that's correct spitzer works at wavelengths where the eye is not sensitive and so when we turn our data into images what we do is we make a correspondence between different infrared wavelengths and different colors on the video monitors. The colors actually have a lot of scientific meaning as well as, I happen to agree with you, that they're visually quite spectacular. You've been working in infrared astronomy for, what, over 30 years now? That's right. Actually, I got started as an undergraduate when I was at Caltech.

I worked on one of the very earliest all-sky surveys, the two-micron sky survey that was being conducted at Caltech, and I had this wonderful opportunity as an undergraduate in the middle 60s. But you had a major disadvantage in that your instruments, while very powerful telescopes, had to work underneath this big atmosphere. That's correct. One of the things that I then did, actually, which sort of taught me the power of going into space for infra-astronomy, was I went to Cornell as a graduate student, and I got to fly sounding rockets as a graduate student. And even in five minutes of observing time, which is what you would get with sounding

rockets, we could do fantastic things doing infrared astronomy from space. And that sort of whetted my appetite for the power of space astronomy. It is absolutely correct that by going into space and cooling the telescope, the telescope wants to be cooled to nearly absolute zero. You gain an enormous amount of sensitivity over anything that you could possibly accomplish from the ground. I guess if sounding rockets whetted your appetite, then a mission that you were part of that had images start or data start coming back in 1983 must have been the first real meal in this area.

Yes, yes. The Infrared Astronomy Satellite, we called it IRAS, was the first all-sky survey in the middle and far infrared wavelengths. And that really just, you know, it's like seeing the universe for the very first time at new wavelengths. And the things that we found were what motivated, basically, building the Spitzer Space Telescope. You've had the Spitzer on orbit now for a little more than a year and a half. Anyone who visits the website, and we will provide that address, that URL, at the end of this conversation,

and on the Planetary Society website where this program can be heard. Anybody who sees these images has got to be extremely impressed. I mean, how big a leap beyond IRIS is the Spitzer Space Telescope? A huge leap. Factors of a thousand or more. Wow. When astronomers can gain a factor of two or four in sensitivity by building a new telescope, it's a major step forward. And we've gained, in some cases, a factor of a hundred,

in other cases, a factor of as much as 10,000 over anything that had come before. Is it fair to say that the engineering challenge presented by Spitzer was even greater than that for a visible light telescope like the Hubble? I believe so. The challenges were different. With Hubble, it was image quality and pointing stability. Our demands are not as high in that area, but on the other

hand, we have a telescope that we maintain at around five and a half degrees Kelvin with 300 liters, that's about 300 quarts of liquid helium, for five years. And doing that was a very difficult challenge, and we have succeeded as we had quote planned it, but I would say fairly beyond our expectations. Have you actually been surprised at the quality of data and the images that have been returned by this instrument? Yes. I think the main thing that has surprised me is how quickly we got to a state of really high-quality data. I'm used to having worked with the IRAS data. It took us many months to really understand the data and be able to process it well, to feel comfortable with it.

And that came very, very quickly. And that came very, very quickly. Does that impressive but still limited amount of liquid helium put a sort of a deadline on your observations? Yes, it does. When the helium runs out, nearly all of our channels no longer can operate. Let's see, there are 11 separate modules in the observatory. And of those, two of them can operate after the helium runs out. The shortest two wavelengths, those are 3.5 and 4.5 microns, which corresponds to about 7 and 9 times the wavelength of visible light.

Those can operate, but everything else will basically end. So obviously you have strong incentive to crowd in as much science as you can, not that they don't on other instruments. Yes, we do. And one of the things I'm very proud of is how much science we pack into our observing program. We're in a rather special orbit, a rather different orbit than something like Hubble. We don't orbit the Earth. We're in a rather special orbit, a rather different orbit than something like Hubble.

We don't orbit the Earth. We orbit the sun. So we trail the Earth as it goes around the sun. So we don't have to go around the Earth and avoid it and avoid the moon and things like that. And so because of that, we can observe nearly all of the time. So we're observing about 22 1⁄2 hours a day. The other hour and a half a day, we're transmitting our data back to the Earth. We're actually observing about 6,600 hours a year, which is about twice as much, or actually more than twice as much,

as any other optical or infrared telescope observes. We need to take a break. I hope when we come back, we can talk about some of the data returned by the Spitzer Space Telescope in this first little more than a year and a half of operation. Our guest is B. Thomas Sofer, Caltech Professor of Physics, who is the Director of the Spitzer Science Center. This incredibly powerful infrared instrument. And we will pick up again with Tom Sofer 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,

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at our exciting and informative website, PlanetarySociety.org. The Planetary Society, exploring new worlds. The Planetary Society, exploring new worlds. B. Thomas Sofer is our guest this week on Planetary Radio. We are talking to him about the Spitzer Space Telescope, sister to the Hubble Space Telescope, one of NASA's great observatories, four of them, I believe, up there, each looking at a different range of electromagnetic radiation. The Spitzer has been at it for a little more than a year and a half and you owe it to yourself, listeners, to take a look at the website

and see some of the incredible images and read about the marvelous science that is being done by this instrument. Tom Sofer, I hate to ask a scientist who works with many other scientists who want time on his instrument to name favorites, but there have to be some results that have been coming back from Spitzer that you would most want to call attention to. Yes, yes. I do have things that are my own personal favorites. Some of them, I have to say, are associated with things that I'm involved in,

but others don't have anything to do with what I do scientifically. Well, that's fair. We'll let you talk about your own work. Okay. The thing which I think Spitzer has done which excites me the most is something I have nothing to do with, which is the direct detection of planets orbiting other stars. This is work by two separate groups, Drake Deming at Goddard Space Flight

Center and Dave Charbonneau at Harvard. Each of them separately has detected the thermal infrared radiation from a planet orbiting a star other than our own. Yeah, Dave Charbonneau was on, I think, just maybe a month and a half ago and gave a lot of credit to your instrument. It's a real tribute to the quality of the instruments, and those instruments were put together by really very dedicated teams. Giovanni Fazio at the Center for Astrophysics and George Ricci at the University of Arizona put together spectacularly good instruments that were used. And without the

quality of the instruments, the observations could not have been made. It's a tribute both to the creative science of the scientists and the quality of the instruments. What are another couple of the projects that you're proudest of? Well, one of the things which, in fairness, is something that I'm associated with is the discovery of distant galaxies that have no optical counterparts, as best we can tell, but are reasonably bright in the thermal infrared. We've been able to determine their distances by getting redshifts from the spectrograph, the instrument that breaks the light up into its component wavelengths,

its component wavelengths, and we find the same kinds of spectral features in these galaxies that we see in nearby galaxies. And so we know what the material is, and we then, by measuring the wavelength of the particular spectral feature, we establish its redshift. And these are galaxies at redshifts of greater than two, which means that their lookback time is something more than 10 billion light years. And we're just starting to understand what they might be. And I'm finding that sort of this discovery of what I believe is a new class of galaxy

to be particularly exciting. That's incredible to look that far back in the history of the universe and see these galaxies which only this instrument could reveal. They weren't available. They couldn't be seen in the optical range. That's correct. And this is one of the things that we wanted to look for, building this observatory that had this enormous gain in sensitivity. The huge gain in sensitivity lets you discover things that were not reachable before.

And that's one of the things that makes it such a wonderfully exciting opportunity. We have just a couple of minutes left. Is there one more you'd like to mention? And then I thought I'd mention one that I got as a NASA press release just last week. I think the other area of science that is really a body of work is the studies that Spitzer has done

that show the assembly of planetary systems, what we call debris disks of planetary systems. I think that the work that Spitzer has done has really clarified, illuminated, and added many new questions to the picture of how the material that is left over from the formation of a star turns itself into a system of planets and dust particles like our own solar system. Well, even as it raises these questions, I assume that in the grander sense, it also confirms a lot of thoughts about how we have come to believe solar systems come into being? I think that that's right. It is confirming that and it's building this picture that tells us how common systems like our own solar system are. Very briefly, here's a press release dated June 9, 2005. NASA's Spitzer captures echo of dead stars rumblings.

There seems to be a major announcement from the Spitzer Space Telescope at least once a week. What's this one all about? least once a week. What's this one all about? This is about seeing, if you will, the propagation of a burst of radiation from a supernova remnant. I believe it's Cassiopeia A. Observers actually found apparently moving material in the infrared, which is associated with the sort of outbursts in what had been a supernova remnant that had gone off some hundreds of years before. It's quite surprising. There is a finite life to this instrument, the Spitzer Space Telescope.

Do you see value someday in replacing it with perhaps an even larger infrared instrument in space? Oh, absolutely. I think that the questions that Spitzer's addressing, we will get our answers, but I think we'll also be raising more and deeper questions, and those will need more powerful instruments, more powerful observatories in space. The James Webb Space Telescope will actually overlap Spitzer wavelengths by a great deal. And so that, when it's launched, will push forward much of the Spitzer science. And there are other NASA missions that are on the drawing boards that will address other elements of the science that Spitzer is working on now. Tom Sofer, I guess we better say goodbye, but congratulations, first of all,

on the early and enormous success of the Spitzer Space Telescope, and thank you so much for joining us on Planetary Radio. And thank you. B. Thomas Sofer has been our guest. He is a professor of physics at Caltech. We've been talking to him about his role as the director of the Spitzer Space Science Center, operators of the Spitzer Space Telescope, returning science as we speak, almost around the clock, as he mentioned.

We're going to come back with Bruce Betts, not quite around the clock, but just a couple of minutes away after we hear from Emily. I'm Emily Lakdawalla, back with Q&A. Why are there fewer clouds in Saturn's blue northern hemisphere than the yellow south? No one knows yet. That's one of the mysteries that Cassini's science team is having fun investigating. The difference probably has to do with the season. Like the Earth, Saturn's spin axis is tilted with respect to its orbit around the Sun. As a result, Saturn has seasons.

Currently, it is winter in Saturn's northern hemisphere, and Saturn's north polar regions get no sunlight at all. This polar winter likely has a strong effect on Saturn's weather. Saturn's rings act to amplify the winter darkness. When it is spring or fall on Saturn, the rings are edge-on to the sun, so there is only a slim ring shadow cast on Saturn near its equator. This was the view that Voyager got. But during the other seasons, the rings cast a broad shadow across Saturn's winter hemisphere. Cassini is now getting dramatic views of these ring shadows covering a wide swath of Saturn's northern hemisphere. The ring shadows act to reduce the amount of sunlight reaching the northern skies.

Exactly how this influences Saturn's weather, clouds, and sky colors isn't understood yet, but Cassini scientists are working hard to figure it all out. Got a question about the universe? Send it to us at planetaryradio at planetary.org. And now here's Matt with more Planetary Radio. Bruce Betts is here. He's the director of projects for the Planetary Society. Must be time for What's Up.

It is indeed, Matt. It is time for What's Up. We're going to have some fun today. I bet we are. Wait till we talk about the trivia contest. It's true. Your listeners got funny and zany, and we love nothing more, although we're a pretty serious bunch around here.

Speaking of which, let's talk about what there is to see in the sky, and I'm going to keep pushing this compact trio of planets coming up. serious bunch around here. Speaking of which, let's talk about what there is to see in the sky, and I'm going to keep pushing this compact trio of planets coming up. June 25th will be the tightest cluster of them, but you can watch them. Mercury is rising up above the western horizon shortly after sunset. It's following the sun, but it's getting farther from the sun. Saturn is getting closer to the sun, and Venus is just hanging out being really, really bright. So what that means is look to the west shortly after sunset. You will see Venus is the brightest star-like object there. Above Venus is Saturn getting lower and lower over the next couple

weeks. And then below Venus for the next couple of weeks is Mercury looking quite bright as well. And those three are going to be within a degree and a half of each other by June 25th. They'll then separate some more, and then a couple of them will snuggle, and we'll give you all the details. But go out there and look at them. Also, look up overhead after sunset in the early evening, and you will see Jupiter looking like the brightest star-like object nearly overhead, and Mars in the predawn sky in the southeast. Very exciting stuff. Okay, what else?

All right. This week in space history, it's Women's Week in space history. Valentina Tereshkova, first woman in space in 1963, and 20 years later, almost to the day, Sally Ride became the first American. 20 years later, almost to the day. Yeah, yeah. Fascinating. It's funny how those things work, yeah.

These things happen all the time in space. It's like Superman knowing all those people with the initials LL, you know? It's really cosmic. It is. It's really like, whoa. Anyway, on to Random Space Fact! For those of you who haven't seen Cosmos, first of all, you should go watch it. But second of all, as Carl Sagan referred to many times in there, we are all star stuff.

Almost all of the elements that we are made up of and our world and everything else were created inside stars. The original universe is thought to have had mostly hydrogen, some helium, a little tiny bit of lithium and beryllium, and not much else. And so the stars and their furnace and their fusion process create the heavier elements. much else. And so the stars and their furnace and their fusion process create the heavier elements for elements that are heavier than iron. They have mostly been created in supernova explosions.

I love this. This is heavier than iron. This is one of my favorite facts. This is this is one of I think one of the top hundred coolest facts of human history is that we are made of star stuff. I've always loved it. I would love to see your top hundred facts of human history. I we are made of star stuff. I've always loved it. I would love to see your top 100 facts of human history. I'll show it to you.

It's in my pocket. I'll show it to you when we're done. Oh, great. Okay, maybe we'll share some more with the folks. Although, like, 30 of them have to do with bubble gum, right? Anyway, on to the trivia contest. We asked you a question which inspired all of you, inspired many of you to great humor, and we thank you for it.

We asked you, where in the solar system is the equator named quill? The equator named quill. That's appropriate. The equator named quill. And how'd we do, Matt? I know how we did. Lots of great, good answers and lots of funny ones. People were inspired.

I don't know what it is about quill that just brought them out of the woodwork. Lots of regulars, lots of people we'd never heard from before. We did get this note from David Donnell, not our winner, David, sorry. But he pointed out that, yes, Pwil is from a Welsh legend, and it's actually pronounced Pwil, but so what? Where's the fun in that? We're not going to that. Thank you for the information, but Pwil.

By the way, did you know that Pwil was the lord of die-fed in Welsh mythology? Oh, is that the new decongestant? It's over the counter now, did you hear? It clears both nostrils. Die-fed. Get it now. We also had a couple of people who wanted to draw Quill as a metaphor. Here's one who sent a picture of Quill because he says it looks like a big sneeze. Wow. I've never noticed that before.

It really does. And someone else said it's like the rust spots starting to form on the doors of his car. Actually, that was Peter in Australia. But our winner, our winner went all out. Boy, this was Paul Carnes. Paul Carnes. I don't know where he's from, actually, but we're going to make the appeal. We'll write back to him and say, hey, Paul, you've got to tell us where you're from.

I suspect Virginia. He is a pharmacist, or as he says, a quill pusher. And that's just the beginning. Well, how appropriate then. He's got, I don't know, 10 or 15 wonderful puns in here. All waste. Waste? Waste on pwill.

So, you know, we're obviously into this. But, Paul, we're going to track you down and we're going to send you that solar sail poster. Is that okay with you? Well, we thought so. What do you got for us next week? I was afraid we had to wait for his answer. For next week, I'm going to challenge you to try to be humorous with this one. It doesn't involve a fun word like puel. I'll try to do better next time. Please. Yes. Okay. Here in the land of fusion, which is always funny, the land of fusion,

which happens inside stars and elsewhere. What is the last element that still releases energy from fusion? The last element that still releases energy when you fuse it. Beyond that, fusion actually takes energy. But up until this element, as you get heavier and heavier amongst the elements, it releases energy. What is that magical element? Not hydrogen. Oh, okay. So a new question. I'm sorry. Well, I eliminated one. No, I'm kidding. It's not. Okay. that magical element? Not hydrogen. Oh, okay.

So a new question. I'm sorry. Well, I eliminated one. No, I'm kidding. It's not. Okay, there's your clue, everyone. It is not hydrogen. Definitely not hydrogen. And it is not einsteinium.

How do they enter? Enter by going to americium. No, no. Enter by going to planetary.org slash radio and find out how to email us your brilliant answer to win a fabulous solar sail poster as solar sail launch approaches. Get that to us by the 20th, the 20th of June at 2 p.m. Pacific time. And you will be entered in this brand new space trivia contest. Part of what's up. Hey, everybody, go out there, look up in the night sky, and think about the miracle of chocolate.

Thank you, and good night. That's my favorite fact, number 39. Yay! He's Bruce Betts, the director of projects for the Planetary Society. He is here every week with What's Up. Oh, by the way, Quill, or Pool, or whatever, is located on Jupiter's moon, Europa. Planetary Radio is produced by the Planetary Society in Pasadena, California.

We look forward to hearing from you. Write to us at planetaryradio at planetary.org. Back next time with the first of two solar sail specials. Have a great week, everyone.