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Guest Host: Rebecca Roberts
The Hubble space telescope went into orbit in 1990, and more than twenty years later the telescope continues to send information and images to scientists studying the universe. Among other contributions, Hubble gave us one of the first images of a planet outside of our solar system and showed scientists that the expansion of the universe is accelerating.
- Jennifer Wiseman Senior Project Scientist for the Hubble Space telescope, NASA's Goddard Flight Center
MS. REBECCA ROBERTSWelcome back, I'm Rebecca Roberts sitting in for Kojo Nnamdi. You've probably seen the pictures, in fact, we've got some of them sitting right here in the studio. The red galaxy streaked with a swirl of yellow and blue gasses and that amazing picture of the Eagle Nebula. A panoramic view of the universe and close ups of Jupiter's moons. The Hubble space telescope has been sending back incredible images of our solar system and galaxies beyond since 1990.
MS. REBECCA ROBERTSBut for scientists, Hubble is about more than pretty pictures. Studying the data and images Hubble sends back has helped scientists understand the very nature of the universe. As Hubble turns 21 this week, we look at some of the space telescopes most amazing discoveries and talk about what its future might be. My guest is Jennifer Wiseman, she directs the laboratory for exoplanets and stellar astrophysics at NASA's Goddard Flight Center. Thank you so much for coming.
MS. JENNIFER WISEMANHi, thank you Rebecca.
ROBERTSSo Hubble is turning 21 this week. Was it expected to last this long?
WISEMANWell, Hubble was launched to be a long lasting platform in the sky. So it was launched with the thought that it could go on for quite some time given that we can service it with astronauts and that astronauts have been able to go back to the telescope periodically to update its instruments and to refurbish it so that it could continue on for years to come. So it was launched, hoping that it would be operational for at least 10 years but an unknown period beyond that and we've been really delighted with its success.
WISEMANAnd so that's why it's a near earth orbit, so that astronauts can reach it.
WISEMANThat's right. It's in near earth orbit. It can be reached by the space shuttle and it's whipping around the earth about every 97 minutes or so.
ROBERTSAnd what has needed the most updating in 21 years?
WISEMANWell, what happens is occasionally you need new gyroscopes, which help the telescope point. You need batteries to help keep it powered. Right now, the Hubble is mostly powered through being recharged by the solar panels on the outside of the telescope that recharges batteries. But the most amazing part for scientists is the fact that you can put in updated science instruments periodically. So that means that even though Hubble is 21 years old, it's basically reborn every time we put in these new science instruments.
WISEMANWe had a wonderful mission two years ago to service the telescope, possibly for the last time, since we won't be having any more space shuttle opportunities, at least in the form that we've known servicing Hubble. And we have basically a brand new observatory in many respects because of these new instruments that we were able to put in a couple of years ago.
ROBERTSAnd when the shuttle program ends, what does that mean for the Hubble?
WISEMANWell, we hope that Hubble will keep operating for many more years. It's in good shape now. I should mention that I'm now the senior project scientist for Hubble. I've stepped down from my role directing the laboratory for (word?) planets there at Goddard so that I could take on this exciting role. Right now when Hubble is very much at the peak of its capabilities, now that it has these new instruments that we installed a couple years ago, it's doing very well. We hope that for several more years it will continue to be a top-notch platform for astronomy in the future years.
WISEMANMaybe as we move toward the latter years of this decade, we may see some of the instruments begin to fail, but hopefully not all at once. And so we'll keep operating as long as we can and as fully as we can to keep the maximal amount of science coming through the telescope. And of course we're looking forward to a major follow on observatory, the James Webb space telescope that's being -- that's in development right now.
ROBERTSMy guest is Jennifer Wiseman. The telescope is the Hubble, and you can join us at 800-433-8850 or send us e-mail, firstname.lastname@example.org. Let's talk a little bit about the things that the Hubble has uncovered. First of all, although this wasn't a new idea, the images from the Hubble have helped confirm it, that not only does the universe continue to expand, that that expansion is accelerating.
WISEMANThat was a tremendous surprise. So one of the major goals for the observatory before it ever launched, was that it would help us really refine the -- knowing the rate of expansion. We knew that the universe was expanding. That was one of the great accomplishments of Edwin Hubble, the name sake for the telescope. But just within recent years, careful observations of distant galaxies and comparing them to more nearby ones and comparing the rate of expanding motion have confirmed that the expansion of the universe is accelerating, and that was a big surprise. We always thought that the expansion rate must be decelerating because gravity was the only thing we knew that would work on that large scale, and it should be slowing down this expansion.
WISEMANBut instead, to find that it's been speeding up for much of the latter history of the universe, it has been a big surprise, and we are terming the cause of that dark energy right now, but we don't really know what the nature of this dark energy is.
ROBERTSYeah. I love terms like that.
ROBERTSIt's sort of a, we are not totally sure term.
WISEMANExactly. It's a popular term in astronomy.
ROBERTSAnd it's interesting that not only is the universe not contracting, right, it's not bouncing back in some way after the big bang, but it's not even slowing down in its expansion. Does that mean that it won't ever slow down?
WISEMANWell, we don't know because we don't know the full nature of what this dark energy is. I mean, there are all sorts of theories that get into things beyond measurable physics, things having to do with string theory and so forth that might, bring us to ideas of bounces and big crunches and so forth, but not in the sense, the classical sense that we had been thinking in simple terms that the universe would just be pulled back together again by gravity because there wasn't anything else to keep pushing it out.
WISEMANAnd now we see that there's something we don't quite understand. It may be something about the nature of gravity itself that we need to understand more fully. So what's happening now are plans for future missions such as W First, which is a mission concept for a future mission that would more carefully detail as we look out of these distant galaxies, how over time the structures of the universe have formed, how gravity has acted over time, and how we can tell the effects of this dark energy, and maybe we can understand the nature of it a little bit better in the future.
ROBERTSLet's take a call from Bob in Crystal City, Va. Bob, welcome to "The Kojo Nnamdi Show."
BOBHi, thank you. I was wondering if the Hubble Telescope was actually looking at the far reaches of our own solar system, and specifically whether or not there was any interest in looking at the (word?) cloud, and perhaps any new planetary bodies that might be at the far reaches of what we consider to be our area.
ROBERTSSomething out there by Pluto?
WISEMANWell, certainly Hubble has been a major player in understanding the universe close to home in our solar system, and in fact, much of our current understanding of what we call the Kuiper Belt, which is this outer realm of rocky debris in our own solar system has been enhanced by Hubble observations. In particular, our understanding that Pluto is one of many, many objects that are similar to it, large rocky bodies. And of course that led to the decision that people either love or hate, but to create a new class of planets that we call dwarf planets of which Pluto is just one of many.
WISEMANAnd of course, we are looking beyond to see what's out there. There are sometimes better ways of doing large field surveys sometimes from ground base telescopes that have larger fields of view, and then Hubble is an excellent follow on telescope to get precise imaging in high resolution imaging of objects that you have once detected.
ROBERTSNow, of course, when you're looking into space, you're looking over both time and distance, right?
ROBERTSWhich is something that can blow your mind if you think about it too hard. But if -- how far away -- long ago is Hubble capable of looking?
WISEMANWell, that's a fabulous question, especially this year, because we are now seeing the faint light from galaxies that are as far away or as far back in time if you want to put it that way, as we have seen before. Astronomers call these great distances, we call them red shifts because as the universe expands, what we get is light that's stretched out as it travels to us by that expansion of space, and things appear redder to us than they would be if we were right at the object. So we see these most reddened or red shifted galaxies by looking in the redder channels or filters on Hubble's instruments.
WISEMANOur new wide field camera three is particularly good at this. It has an infrared channel, and astronomers have worked very hard to see if they can tweak out the most distant galaxies in these deep fields. I should say that the Hubble deep fields are my favorites, and these are these deep images that show you countless galaxies that you see simply because you're integrating light for a long time, and seeing the (unintelligible) objects really realizing visually how many galaxies there are.
WISEMANThese most distant ones that are being pulled out now, if you think about it, are more from the infant stages of our universe. We believe the universe is about 13.7 billion years old, that it's been that long since the big bang, and we're seeing some of these galaxies as they emitted their light from within that first .7 billion years.
WISEMANSo just a few hundred million years after the beginning of our universe, we see these galaxies starting in their sort of infant forms, to light up.
ROBERTSSo you're looking back 13 billion years?
WISEMANWe are, yes. And that's a humbling though and experience. And the fact is that we're not -- we're seeing these sort of scruffy infant galaxies. They're not the big spiral beautiful things that we see closer to our milky way. They are the first gatherings of stars and gas that we believe over time evolved by merging with other galaxies, and through title interactions and gravity that can form these nice beautiful structures we see. But the scruffy ones are quite interesting because we're seeing them as they first began to form, and we're hoping that even future telescopes like the James Webb space telescope that will be able to see even farther into the infrared, will see even younger galaxies or proto galaxies.
ROBERTSDoes that mean there's some way to see the big bang, or the instant after the big bang?
WISEMANWell, you can't see, for reasons of the physics of the very early high-energy ionized material, you can't see all the way back in that sense, but you can see very closely after the big bang. You can the first burst of escaping radiation. We call it the cosmic microwave background emission. And this was discovered by astute scientists a few decades ago, and they were -- a Nobel Prize was awarded for this detection. So we can in fact see background radiation everywhere we look. Because if you think about it, the big bang actually happened everywhere in space all at the same time.
WISEMANAnd so that background radiation is everywhere, and it's caught along with this expansion of space cooling over time. So it takes very sensitive telescopes to pick it out. So in that sense, yes, we can see almost to the very beginning of time.
ROBERTSAnd I should say that it is a little too bad that this is radio because you've brought these just breathtaking images that I'm getting to see. Is there a place that our audience can see these online?
WISEMANAbsolutely. Everyone should go to hubblesite.org. That's H-U-B-B-L-E-S-I-T-E dot O-R-G, hublesite.org, and that will take you to a gallery like none you've ever seen before. It has a gallery of just about every Hubble image that you would like to see with explanations of what you're seeing. And, of course, Hubble has contributed to so many different branches of astronomy, it's hard to list it all briefly, but it -- we're including also things like how stars form, and Hubble was one of the first telescopes to really discern these discs of dust and debris around young stars, and to figure out that hey, maybe that's where planets might be forming as stars form.
WISEMANAnd then to our great delight, Hubble was one of two observatories that imaged for the first time extra solar planets recently. So in Hubble's case it was the planet Fomalhaut b. What an exciting accomplishment to actually image an extra solar planet. Now, we've been studying extra solar planets before, and we continue to in other exciting ways. So Hubble is a contributor to I think one of the hottest topics in astronomy today.
ROBERTSWell, let's talk about extra solar planets, your field. So these are planets that orbit around a star other than our own sun.
ROBERTSAnd they are not largely detected by seeing them.
ROBERTSThat's sort of push and pull against the star that you can detect through other means.
WISEMANThat's right. So extra solar planets have up until just recently have always been just the subject of science fiction in a sense that, you know, are there planets outside our solar system or not. Well, now we know the answer is yes, but that's only within the last couple of decades that we started detecting them, and as you say, it's usually indirectly. Because these objects are very small, very dim, they don't shine their own visible light. So the way most of them have been detected is through ground-based telescopes watching stars and seeing if they can see the wobble of star that's caused by the push and pull of an orbiting planet.
WISEMANHundreds of planets have been detected this way. Now, the next step is trying to characterize them, trying to find out something about them. And one thing that Hubble was a pioneer in is understanding the composition of the atmosphere of some of these extra solar planets.
ROBERTSHow does that work?
WISEMANWell, one in particular is the process of transit. So if you happen to look at a system that fortuitously has the planet orbiting its star along our line of sight, that planet will pass in front of its parent star every orbit, and the light from that star will past through the outer rim of that planet, the outer edges, which means it passing through its atmosphere if his has one, and that atmosphere may take a gulp out of some of that light. We call it absorption, certain gasses, atoms and molecules in the atmosphere will absorb particular frequencies of light coming from the background star.
WISEMANSo then when we see that star light, we see the stuff that's been munched out of it by the orbiting planet, and we can tell from that what some of these components are in the XO planet atmosphere. So for example, a planet like HD209548b is a very popular one for people studying XO planets.
ROBERTSAnd it's a much better name.
WISEMANYes. But we -- it was sodium, carbon, hydrogen, oxygen, these kinds of things were found. Now, keep in mind that most of the extra solar planets that we're able to detect and see right now are the large gas giant planets like...
WISEMAN…Jupiters and Neptunes. But we are getting to the point where we are detecting smaller and smaller extra solar planets. Of course, the goal is to try to detect an earth-like planet. Hubble probably won't be the instrument to do that, but what Hubble is doing are these fabulous transit studies of some of these larger planets. And we're also working in concert with other facilities like the Kepler Space Telescope which is another NASA facility, which is wholly dedicated to looking for these transiting planetary systems and finding -- I think they found over a thousand candidates right now.
WISEMANSo it's a very exciting time for studying XO planets, looking forward to finding planets with evidence perhaps of habitability or even biological activity in the not-too-distant future with some of these current or future facilities. That's our goal.
ROBERTSAnd the telescope that's in the works now, the James Webb Telescope that you've referenced a couple of times, is that likely to be the instrument to...
WISEMANWell, it will be a fabulous instrument for studying these transiting planetary systems for looking at components of atmospheres and also for finding what's going on in these zones where extra solar planets form. So it will a really good -- what I think of as a drill to drill into these very dense dusty discs around young stars, and perhaps to even discern a planet buried in those discs, or to find out how planets form, and will be able to tell us quite a lot about what we call super earths which are objects maybe just a few times larger than Earth.
ROBERTSBut not in gas giants.
WISEMANAnd including gas giants, yes, of course. But we -- what we also hope for a future facility that will be able to get down to things the size of earth or smaller and enable us to do what we call spectroscopy which is this detailed study of the atmospheres looking for biomarkers. A biomarker would be some sort of chemical signature that we could be pretty sure was caused by the presence of life on that planet. So now, keep in mind that astronomers would be thrilled if we found even a bacteria or a fungus on another planet somewhere.
WISEMANSo we're not the ones for the most part that are thinking of Klingon civilizations right now. We're hoping for some kind of photosynthesis or anything of that nature would be a tremendous excitement for us.
ROBERTSWe have a comment posted on our website by Randy who says, "I'm working at the U.S. Naval Observatory with a 26-inch refractor. I used to claim it was the Hubble of the 19th century. It discovered moons of Mars in 1873, which is astounding. Our 26-inch is still working 140 years later. Why couldn't the Hubble run another century?"
WISEMANWell, again, it's just -- for Hubble, it's a matter of being able to keep up the hardware and keep it serviced. And since the Space Shuttle program is winding down, we sort of have options of trying to develop some other means of servicing the Hubble, or of looking for future observatories that will extend the great science of Hubble in other ways. We have a wonderful astronomy community in the United States, and all over the world.
WISEMANAnd in the U.S. we have professional astronomers who advise NASA and the National Academies of Science on what kinds of astronomy facilities both on the ground and in space would be the best for getting the kind of science that we want. We look to that advice. We call it the decadal survey, for what kinds of telescopes and observatories to use in the future and the present. But I can tell you that right now Hubble is at its peak and it's public support that keeps Hubble going and in the eye of everyone around the world. So we appreciate the public support and excitement for the observatory.
ROBERTSJennifer Wiseman, senior project scientist for the Hubble Space Telescope at NASA's Goddard Flight Center. Thank you so much.
ROBERTSAnd you can see some of those Hubble pictures at our website. I'm Rebecca Roberts sitting in for Kojo Nnamdi. Thanks for joining us.
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