Planetary Radio: Space Exploration, Astronomy and Science - The Universe in Ultraviolet: Bill Blair on the FUSE Mission

Episode Date: October 29, 2007

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Exploring the ultraviolet and how to kill your spacecraft, 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. After eight wonderfully productive years, the Fuse spacecraft is dead. And Bill Blair helped to kill it. We'll find out why, and hear about the great success of this little-known mission. Emily Lakdawalla will tell us why the New Horizons mission, now speeding toward Pluto, is unlikely to help unravel the Pioneer anomaly.

And Bruce Batts will tell us where to look in the night sky for the coolest of naked-eye objects. He'll also unveil our second space trivia contest that could make you eligible for one of our fifth anniversary grand prizes, including a fragment of Mars meteorite. I wish we had more time for headlines from around the solar system and beyond. We'll just mention that Space Shuttle Discovery is safely docked with the International Space Station, and Chang'e 1, the Chinese lunar orbiter, is on its way to our planet's only natural satellite. Check out our coverage at planetary.org, where you should soon be able to see a live picture

from the Planetary Society-funded Optical SETI telescope operated by Harvard University. It's the biggest optical telescope east of the Mississippi, and it's watching for a flash of laser light that would tell us we are not alone. Time to see Emily play among the stars as she presents this week's Q&A. I'll be right back with Bill Blair and the Fuse mission. Regular listeners to this show will know that the Pioneer anomaly is an unexplained acceleration that has shown up in careful analysis of radio tracking data from the two Pioneer spacecraft. After taking into account all forces acting on the Pioneers, radio scientists have been unable to account for this tiny acceleration, which amounts to about one ten-billionth of the acceleration due to gravity at the Earth's surface. one ten-billionth of the acceleration due to gravity at the Earth's surface. It's possible that the acceleration has to do with some force that is peculiar to the design of the Pioneer spacecraft, so it'd be valuable to check whether other

spacecraft at the edge of our solar system are experiencing the same acceleration. Unfortunately, the Voyager spacecraft can't be tracked precisely enough for Pioneer anomaly analysis. The Pioneers are very stable in their orientation because they spin continuously. By contrast, the Voyagers are three-axis stabilized and adjust their pointing with tiny puffs of gas from their thrusters. These puffs of gas are many orders of magnitude more powerful than the tiny acceleration of the Pioneer anomaly, so the effect, if it exists, is undetectable on the Voyagers. New Horizons happens to be spin-stabilized like the Pioneers.

Can New Horizons be used to check for the Pioneer anomaly? Stay tuned to Planetary Radio to find out. Dr. William Blair is an astrophysicist and research professor at the Johns Hopkins University in Maryland. That's where he has served as chief of observatory operations for FUSE, the Far Ultraviolet Spectroscopic Explorer. Okay, raise your hands if you've heard of it. Uh-huh, not too many hands. And yet, FUSE has just completed an eight-year mission

that has told us how much water has escaped from Mars, that some exotic planets may be starting to form around a nearby star, and that our Milky Way galaxy is much more dynamic than anyone thought. I talked to Bill just days after he had helped to turn off Fuse forever. Bill Blair, congratulations to you and the entire Fuse team on the completion of a very successful mission, as acknowledged by Alan Stern, NASA Associate Administrator, in a recent news release. Fuse accomplished all of its mission goals and more. It vastly increased our understanding of our galaxy's evolution, and many exotic

phenomena left a strong legacy on which to build the next generation of investigations and missions. Pretty nice praise. Well, yeah, thanks very much, Matt. It was kind of a sad week to have to turn the old bird off, but it had gotten eight good years of service and much more than anybody expected. We had to work real hard to do that, but ultimately it was a very successful mission. Summarize the mission here. Summarize what FUSE was all about. Well, the FUSE satellite, I guess I like to describe, you know, space telescopes and even ground-based telescopes as the tools that an astronomer uses, just like a carpenter has different kinds of hammers or different kinds of saws for different jobs. Astronomers have different kinds of telescopes and instruments on those telescopes.

The Fuse satellite was basically a component of NASA's astronomical tool belt, if you will, that did a very specialized job. It looked at far ultraviolet light, basically in the ultraviolet where Hubble had ultraviolet sensitivity where its sensitivity dropped off is right where we were picking up and extending down to shorter wavelengths of light or farther into the ultraviolet part of the spectrum. Our scientific device was called a spectrograph. It's a device that breaks the light up into a spectrum for analysis. To an astronomer, a spectrum is really just a plot of the brightness or the intensity of light as a function of frequency or wavelength of the light. And we were looking at ultraviolet light, and the data that are

produced are basically graphs, squiggly lines, but those squiggly lines contain just incredible amounts of information about the objects that are being observed, or in some cases the material that is between the object and the observer that imprints a fingerprint onto that spectrum. Why is short ultraviolet such a rich place to look for these spectra? Well, that's a good question. This little range of the spectrum that Fuse observed, we actually observed it at fairly high resolution. That is to say we really spread the light out a lot to look at the details.

And that's because there's so much astrophysical action, if you will, in this little part of the spectrum that we observed, that it was worth a mission in its own right to look at this spectral range. This little region of the light spectrum contains the primary absorptions or emissions from atomic hydrogen, the Lyman series, it's called, of lines from the hydrogen atom, which, of course, is the most abundant thing in the universe. And molecular hydrogen has a lot of bands that are connected to the ground state,

so it's the coldest form of molecular hydrogen. Again, a large component of what's out there in space between the stars, as well as a number of other features in this spectral range that come from very hot gas that allow you to sample things like the halo of our galaxy, where supernovae have blown hot gases out off the plane of our galaxy and into the halo, and our sight lines intersect this material, and you can learn about these regions. Basically, regions that are typically invisible to telescopes, and we sense their presence kind of indirectly using background sources

and seeing the imprint that that gas in the foreground causes onto the spectrum of the background objects. As you said, the primary product of this spacecraft were these spectrographs and not so much pictures. And I wonder if maybe that's one reason, while Fuse may have gathered an enormous amount of attention and praise from astronomers and astrophysicists, it certainly is not as well known as, for example, the Hubble. Yeah. Yeah, it's a sad story. We've always had a tough time getting our science case out there in front of the public because of that.

You know, Hubble has spectrographs, too, and how often do you hear about the work that Hubble does with its spectrographs? You don't see them on the cover of the newspaper, do you? Not very often, and so that's why we haven't probably seen a lot of press. But there's a famous line from one of the scientists that was on the team that proposed FUSE to NASA. He said, if a picture is worth a thousand words, a spectrum is worth a thousand pictures. That's great. There's just so much physical information in a spectrogram of a distant object. And when you think about it, these are objects.

I mean, okay, we get an occasional meteorite or something coming in, but basically these objects weigh out in the universe. We cannot get our hands on and bring into the laboratory. The only way we can learn about them is to dissect the light that they send across the universe to us. And FUSE was just a spectacular mission for doing that job. So I'll give you an example. Let's say we look at an object in the Large Magellanic Cloud nearby galaxy, one of our little satellite galaxies. We looked at about 300 objects in the Magellanic Cloud galaxies.

There's two of them, large and small. For each of those spectra, what we get is we get the spectrum of the star, which is of interest to somebody. We get the imprint of the hot gas and cold gas on the sight line in the Magellanic Cloud galaxy. We also see the imprint of the Milky Way halo in that same data. And so somebody else goes and looks at that part of the data. And so you're doing three projects in one every time you look at a star in the Magellanic Clouds. It's really quite dramatic how much information is in these light spectra. One of the more recent reports on objects in the universe that few studied, and this was this double star system, which looks like just a very bright single star from Earth,

single star from Earth, but turns out this LH 54-425 is two of the most powerful stars that are getting uncomfortably close to each other. What did FUSE do with these? Well, because FUSE observes at such high spectral resolution, that is to say, spreads the light way out, it is quite sensitive to small velocity shifts in the features that we see in the light spectrum. And so by observing this object over a period of time, what looked like a single star showed a signature of movement of the lines in the spectrum as a function of time that indicated that it was actually a binary star.

Fuse contribution there in particular is, again, there is a feature of highly ionized oxygen down in the fuse range. It's kind of a unique diagnostic. It comes from gas of about a temperature of 300,000 Kelvin. And so it's intermediate between X-ray temperatures and what you normally see in the optical or the near ultraviolet part of the spectrum. And so these features actually are diagnostics of the winds from these very hot stars. We saw a very clear signature, not only that there was a wind there, but that it was varying in a way that was consistent with this being a very powerful binary star with a period of, I think it was about two and a quarter days.

Yeah, and some of the other numbers here are incredible. The more massive of these two stars, shedding material, 500 trillion tons per second at five and a half million miles per hour. Yeah, those are pretty astounding numbers, but you know, this is, I guess you could say they're astronomical. Yes, you certainly could. When you put almost any numbers from astronomy into tons per second or miles per hour, it sounds very, very high. These are very extreme conditions, obviously, but they're certainly not unheard of in our wild and wonderful universe out there. It's just a very unusual system to find two stars this massive in such a close dance with each other. I mean, basically, it's a laboratory.

You couldn't set this up in the laboratory and do it. And yet nature provides, you know, the opportunity to look at these things and try to understand the physics of what's going on. More from Bill Blair of the Fuse Mission when Planetary Radio continues in a minute. Hey, Bill Nye, the science guy here. I hope you're enjoying Planetary Radio. We put a lot of work into the show and all our other great Planetary Society projects. I've been a member since the disco era. Now I'm the society's vice president. And you may well ask, why do we go to all this trouble? Simple. We believe in the PB&J, the passion, beauty, and joy of space exploration. You probably do too, or you wouldn't be listening. Of course, you can do more than just listen. You can become part of the action, helping us fly solar sails,

discover new planets, and search for extraterrestrial intelligence and life elsewhere in the universe. Here's how to find out more. 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. We're talking with Bill Blair of the Johns Hopkins University, where he serves as Chief of Observatory operations for the FUSE mission. That's the Far Ultraviolet Spectroscopic Explorer. Let's talk a little bit about this mission. You said it was eight years, but it didn't start out as an eight-year mission. No, it was originally slated for three years of science operations. Basically, we launched back in June of 99, and it does take a while to

commission an observatory like this. It was about December 1999 that we actually got rolling on the science part of the mission. So we expected to get about three years beyond that. And I mean, in reality, everyone hopes, I think, when you put this much effort into a mission and you launch it, that it will last more than that primary mission length. But there's no guarantees in this business, and there are a number of things that happened to us that almost knocked us offline even before the end of that three-year period. But when we got into the mission and we started getting results and NASA saw that it was very successful, they opened up the observatory to the astronomical community at large to write proposals.

Every year they would solicit proposals and select a fraction of those to be actually done with the satellite. And we would process the data, send it out to the astronomers, and they have, to this date anyway, have published about 1,200 papers on FUSE results in the astronomical literature and technical literature as well about some of our problems and recoveries from those problems as well. It's been very interesting to people. So NASA just kept the ball rolling on this. They could sense that it was successful, and people had – it wasn't just doing more of the same as it got older. People were finding new things to do with it as a function of time.

One example of that might be we had no conception at the time that FUSE launched that it would ever be useful for anything that had to do with the formation of planetary systems around other stars. And yet, of course, over the last decade, that's become a very hot topic in astronomy. And there were observers that proposed to use FUSE to look at stars like the Beta Pictoris system and other systems that have disks of gas and dust around them that are thought to be forming planets. Fuse's unique contribution there is that it could see the gaseous component. The Spitzer Space Telescope and other infrared telescopes can look at the dust that is heated

as the star system or the planetary system is forming, but they are not very efficient at seeing the gaseous component. And so by using Fuse in combination with Spitzer or one of the other telescopes became a very powerful tool then for investigating these planetary nurseries, if you will, something we just wasn't even conceived at the time that Fuse launched. These kinds of stories are always one of my favorite categories of tales of science, the completely unexpected benefits that come from a scientific investigation or instrument. It seems to happen over and over. Yep. This falls under the category

of all things must pass, even very good things. The Fuse mission is coming to an end. In fact, you put a report on the website just a few days ago, on the 18th of October, about how you went about killing Fuse. Yes, it's a sad story. Well, Fuse does not have any fuel or hydrazine or anything like that on board that it can direct it around after it's left on its own up there. It was completely operated with electricity from solar panels and from spinning wheels that are called momentum wheels or reaction wheels that pointed the satellite around the sky. And it was actually the demise of the reaction wheels.

Slowly over the years, we lost several and had to find ways of running the observatory without all four reaction wheels. And we ultimately got down to one. And it was the failure of that final reaction wheel this summer that finally killed the science operations of the project. So, Fuse is up there. We had been maintaining it in a safe mode where it's just pointing straight down at the Earth as it goes around. It took some babysitting to keep it in that safe mode, and so once we really leave it alone, it's going to tumble around up there.

It's going to stay in its orbit, but I mean, it will not be held in an inertial pointing position. It will be flopping around. The solar panels will occasionally turn toward the sun. Well, you don't want things like, you know, batteries to overcharge and possibly rupture or even potentially explode, I suppose, and blow parts of fuse all over the orbit up there where it's going to bother somebody else, you really want to make this thing as inert as you can and just let its orbit slowly decay over the next roughly 30 years, and it will eventually burn up in the atmosphere. But it'll take something like 30 years before that happens. So we had to put it to bed in a way that it was really going to stay quiet. And the way we did that was to discharge its batteries down as low as we could

and still have enough power to send the final commands, then turn the computers on in a standby mode so that they can't process any commands, and even if they do come alive again, then finally to turn off its radio transmitter so that it would remain quiet forevermore, as Edgar Allan Poe might say. And as you said, fuseuse is dead, long live Fuse. I guess it lives on through its data and its science legacy. It really will. You know, even with the number of publications that have been done to date,

there are so many more in the works. I mean, I've got a half a dozen myself that I haven't had time to get written up that will slowly be coming out over the next few years. that I haven't had time to get written up that will slowly be coming out over the next few years. We took something like 130 million seconds of science data with FUSE over the last eight years, and those data are being reprocessed with our current calibration software and will be archived for future astronomers to use. And so we actually have a big job to do to get that done still, even though the on-orbit operations are done,

and write up documentation for future users to understand what FUSE data are all about. And with that, Bill, we are out of time. Thank you very much for coming on Planetary Radio and giving us this wonderful wrap-up on the FUSE mission, which really, as you've just demonstrated, is not over yet. Okay, Matt. Well, thanks very much. I appreciate the interest. Dr. William Blair is an astrophysicist and research professor at Johns Hopkins University. He is the chief of observatory operations for the FUSE project. And FUSE just completed eight extremely successful years of astronomical observing. FUSE, the far ultraviolet spectroscopic explorer. We will be back with Bruce Betts in this week's edition of What's Up in the Night Sky,

our own little bit of exploring, right after a return visit by Emily. I'm Emily Lakdawalla, back with Q&A. Can radio scientists use New Horizons to check for the Pioneer anomaly? Like the radio scientists use New Horizons to check for the Pioneer anomaly? Like the Pioneers, New Horizons is spin-stabilized, so if the Pioneer anomaly is a real effect and not just some fluke caused by the design of the Pioneer spacecraft, it should be detectable in the New Horizons radio tracking data. However, even if it is detectable, it may

not be detected. In order to determine whether New Horizons shows the Pioneer anomaly, scientists need to develop a detailed model of all of the forces that may come from within the spacecraft, and then they need to perform much more detailed radio tracking than is strictly necessary for New Horizons to accomplish its science mission to Pluto and the Kuiper Belt. These things cost money, probably a couple of million dollars. In an era of very tight budgets, NASA has elected to spend its millions elsewhere. So New Horizons could be used to search for the Pioneer anomaly,

but at least for the present, this search is not going to get done. Got a question about the universe? Send it to us at planetaryradio at planetary.org. And now here's Matt with more Planetary Radio. Got a question about the universe? Send it to us at planetaryradio at planetary.org. And now here's Matt with more Planetary Radio. Time for What's Up on Planetary Radio. I'm in the room with Bruce Betts, the director of projects with the Planetary Society, here in the cavernous studio at the Planetary Society headquarters.

It's just not as much fun doing this on the phone. It's so much better to see you across the table. Aww. What's up in the night sky? Got in the evening sky. You can still catch Jupiter in the early evening just after sunset over in the west. But gosh, it's starting to get tough even for the super bright jupiter as it gets lower and lower in the sky mars on the other hand will start to fill your evening with joy and delight as it is rising in the in the mid evening in the east uh looking reddish now almost as bright as the brightest star in the sky as we move towards its late december opposition or closest point in

its orbit and then it's also up high in the sky in the pre-dawn. In the pre-dawn, you can also catch Venus still in the east. Getting lower on the horizon is the brightest star-like object. And look above Venus, and you'll find Saturn getting higher in the pre-dawn sky. And always a lovely treat with a small telescope. Go out and check out those rings. I didn't warn you that I was going to ask you about this. Did you read something about a comet that has, like, flared, come out of no place?

Yes, there is a flary comet. One of the discoveries by the LONIOS program. So it's a binocular-type object, but it is out there, and we'll give you a little more information perhaps next week. But in the meantime, you will need basically a finder chart for it. So check it out on the web, one of the many discovered by the Loneos program, L-O-N-E-O-S. Okay, next week. Yeah.

Okay, what else you got? Well, we've got a random space fact. Is this our... No? No? Yeah, this is our Halloween show, isn't it? That was good. Scary kitties.

You know what's really scary? What? The most energetic thing in the universe for a brief amount of time. That's Lou Friedman after a trip to Russia. All right. The second most energetic thing in the universe, gamma ray bursts, just after Lou Friedman. Yes, these are the most energetic things in the universe

for the few seconds where they burst. There are a couple different kinds we've learned. We went from knowing almost nothing for three decades to now having some very cool spacecraft that have tracked these little buggers down all across the universe and found out the more we learn, the stranger they are. And we've got some that the longer period ones, and for a longer period we're talking more than two seconds,

those seem to be the formation of black holes, the hypernova going to a black hole, just spewing gamma rays all over the place. And then we have the short period ones where we have a couple of mostly burned out stars that are orbiting each other and finally crash together. We just talked about something like this during today's interview with Bill Blair. These two O-type stars that sometime in the next million years or so may crash together. They're fierce. It's amazing. They're fierce. Bring it, baby. But this is perfect for Halloween. It is scary stuff. Yeah, one wouldn't get into what it would do to the Earth if one went off. But fortunately, we're probably okay any given day.

Yeah, let's stay on the other side of the galaxy from one of those at least. Yeah, at least. Maybe more so. Yeah, more so. All right, let's go on to our trivia contest. We asked you who flew both the X-15 and the space shuttle. Who flew the X-15 and the space shuttle? How did we do, Matt?

Either more people are listening or more people want a T-shirt because this is the last group of people that won't be eligible for the fifth anniversary prize that we'll come back to, or prizes. But we still got a lot of people entering. You know who got it right? John Eric Thompson. John Eric Thompson of Murrieta, California, not too far from where we are, who said Joe Engel. Joe Engel flew about the X-15 and then early flight of the space shuttle.

Couple of flights of the space shuttle, I was told, and some of the approach and landing tests in Edwards. And then a couple of people mentioned this weird thing about Apollo. He was supposed to be on Apollo 17, got bumped to Apollo 18, which never happened. Yeah, that's not good. Sad story. Okay, I got to tell you this, because I told you before we started recording, we got the worst trivia contest entry we've ever gotten. By all means. Let's discuss it. Here it is from Greg Liberace.

That is his name. He said that the only person to fly both the X-15 and the space shuttle, noted game show host and explorer Wink Martindale. Wow. Who knew? Who knew? No. Obviously, that's wrong.

He was the only person to fly the X-15 and also fly an Apollo. Who knew? Who knew? No, obviously that's wrong. He was the only person to fly the X-15 and also fly an Apollo. Well, Greg does point out here. He replaced Joe Engel on Apollo 17. Is that right? He's the one who beat him out? Yeah. Greg says, by the way, I am sane, just very bored.

Well, now we're less bored, thanks to Greg. Speaking of great game show hosts, let's give you another trivia contest. We have now two spacecraft headed off to the moon, two more next year, as part of what Planetary Society is calling the International Lunar Decade. Pretty simple one here. Tell us the names of the two spacecraft on their way or orbiting the moon now. And the two that are scheduled to be launched in 2008, go to planetary.org slash radio to get us your entries. So they have to do all four? All four.

Okay. It's all four or don't even bother. Okay. They've got to get them to us by November 5, 2007, 2 p.m. Pacific time on that Monday. And by the way, this will be your second opportunity to get in on our fifth anniversary prize spectacular, prize Lollapalooza, which we're going to do at the end of November for our November 26th show. Would that be a prize-a-palooza? Yes, it would. I like that better.

Yes, yes. Prize-a-palooza. I can't say it, but you say it again. prize-a-palooza? Yes, it would. I like that better. It's a prize-a-palooza. I can't say it, but you say it again. Prize-a-palooza! What he said. Five weeks only. Enter and have a chance to win a Mars meteorite. That's right, an actual piece of a Mars meteorite,

as well as other fabulous prizes. Enter and you'll be entered into our random contest of all those who enter. We're done. All right, everybody. Go out there, look up in the night sky, and think about little flecks of Mars hitting you in the head. Thank you, and good night.

It could happen. That would explain a lot, actually. He's Bruce Betts, the director of projects for the Planetary Society, and he joins us every week here for What's Up. By the way, we want to thank SpaceFlory.com for that Mars meteorite fragment. One of you will win. We'll tell you about more prizes next week. Planetary Radio is produced by the Planetary Society in Pasadena, California.

Have a great week. Thank you.