Tribe.net. Local Connections Serge http://astro.tribe.net/thread/3dbd846a-f480-41e0-acaf-0ce556205e0a#1a16c6f7-0acc-4a6e-bac0-117a8120b414 2009-05-09T14:22:45Z 2009-05-09T14:22:45Z

Whitney Clavin 818-354-4673 Jet Propulsion Laboratory, Pasadena, Calif. whitney.clavin@jpl.nasa.gov NEWS RELEASE: 2009-078, May 6, 2009 PASADENA, Calif. -- The primary mission of NASA's Spitzer Space Telescope is about to end after more than five-and-a-half years of probing the cosmos with its keen infrared eye. Within about a week of May 12, the telescope is expected to run out of the liquid helium needed to chill some of its instruments to operating temperatures. The end of the coolant will begin a new era for Spitzer. The telescope will start its "warm" mission with two channels of one instrument still working at full capacity. Some of the science explored by a warm Spitzer will be the same, and some will be entirely new. "We like to think of Spitzer as being reborn," said Robert Wilson, Spitzer project manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "Spitzer led an amazing life, performing above and beyond its call of duty. Its primary mission might be over, but it will tackle new scientific pursuits, and more breakthroughs are sure to come." Spitzer is the last of NASA's Great Observatories, a suite of telescopes designed to see the visible and invisible colors of the universe. The suite also includes NASA's Hubble and Chandra space telescopes. Spitzer has explored, with unprecedented sensitivity, the infrared side of the cosmos, where dark, dusty and distant objects hide. For a telescope to detect infrared light -- essentially heat -- from cool cosmic objects, it must have very little heat of its own. During the past five years, liquid helium has run through Spitzer's "veins," keeping its three instruments chilled to -456 degrees Fahrenheit (-271 Celsius), or less than 3 degrees above absolute zero, the coldest temperature theoretically attainable. The cryogen was projected to last as little as two-and-a-half years, but Spitzer's efficient design and careful operations enabled it to last more than five-and-a-half years. Spitzer's new "warm" temperature is still quite chilly at -404 degrees Fahrenheit (-242 Celsius) -- much colder than a winter day in Antarctica when temperatures sometimes reach -75 degrees Fahrenheit (-59 Celsius). This temperature rise means two of Spitzer's instruments -- its longer wavelength multiband imaging photometer and its infrared spectrograph -- will no longer be cold enough to detect cool objects in space. However, the telescope's two shortest-wavelength detectors in its infrared array camera will continue to function perfectly. They will still pick up the glow from a range of objects: asteroids in our solar system, dusty stars, planet-forming disks, gas-giant planets and distant galaxies. In addition, Spitzer still will be able to see through the dust that permeates our galaxy and blocks visible-light views. "We will do exciting and important science with these two infrared channels," said Spitzer Project Scientist Michael Werner of JPL. Werner has been working on Spitzer for more than 30 years. "Our new science program takes advantage of what these channels do best. We're focusing on aspects of the cosmos that we still have much to learn about." Since its launch from Cape Canaveral, Fla., on Aug. 25, 2003, Spitzer has made countless breakthroughs in astronomy. Observations of comets both near and far have established that the stuff of comets and planets is similar throughout the galaxy. Breathtaking photos of dusty stellar nests have led to new insights into how stars are born. And Spitzer's eye on the very distant universe, billions of light-years away, has revealed hundreds of massive black holes lurking in the dark. Perhaps the most revolutionary and surprising Spitzer findings involve planets around other stars, called exoplanets. Exoplanets are, in almost all cases, too close to their parent stars to be seen from our Earthly point of view. Nevertheless, planet hunters continue to uncover them by looking for changes in the parent stars. Before Spitzer, everything we knew about exoplanets came from indirect observations such as these. In 2005, Spitzer detected the first light, or photons, from an exoplanet. In a clever technique, now referred to as the secondary-eclipse method, Spitzer was able to collect the light of a hot, gaseous exoplanet and learn about its temperature. Further detailed spectroscopic studies later revealed more about the atmospheres, or "weather," on similar planets. More recently, Spitzer witnessed changes in the weather on a wildly eccentric gas exoplanet -- a storm of colossal proportions brewing up in a matter of hours before quickly settling down. "Nobody had any idea Spitzer would be able to directly study exoplanets when we designed it," Werner said. "When astronomers planned the first observations, we had no idea if they would work. To our amazement and delight, they did." These are a few of Spitzer's achievements during the past five-and-a-half years. Data from the telescope are cited in more than 1,500 scientific papers. And scientists and engineers expect the rewards to keep on coming during Spitzer's golden years. Some of Spitzer's new pursuits include refining estimates of Hubble's constant, or the rate at which our universe is stretching apart; searching for galaxies at the edge of the universe; assessing how often potentially hazardous asteroids might impact Earth by measuring the sizes of asteroids; and characterizing the atmospheres of gas-giant planets expected to be discovered soon by NASA's Kepler mission. As was true during the cold Spitzer mission, these and the other programs are selected through a competition in which scientists from around the world are invited to participate. JPL manages the Spitzer mission for NASA's Science Mission Directorate in Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Lockheed Martin Space Systems in Denver, and Ball Aerospace & Technologies Corp. in Boulder, Colo. support mission and science operations. NASA's Goddard Space Flight Center in Greenbelt, Md., built Spitzer's infrared array camera; the instrument's principal investigator is Giovanni Fazio of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. Ball Aerospace & Technology Corp. built Spitzer's infrared spectrograph; its principal investigator is Jim Houck of Cornell University in Ithaca, N.Y. Ball Aerospace & Technology Corp. and the University of Arizona in Tucson, built the multiband imaging photometer for Spitzer; its principal investigator is George Rieke of the University of Arizona. More information about Spitzer is online at http://www.nasa.gov/spitzer and http://www.spitzer.caltech.edu/spitzer . -end- From: subscription email

Serge 2009-05-09T14:22:45Z Serge http://astro.tribe.net/thread/3dbd846a-f480-41e0-acaf-0ce556205e0a#097ee187-dc6a-4c0f-ba90-cf830d583be1 2009-05-06T14:59:12Z 2009-05-06T14:47:50Z

Feature, May 4, 2009 NASA's Spitzer Space Telescope is about to use its last drop of the coolant that has chilled it for the past five-and-a-half years. On about May 12, give or take a week or so, the observatory is predicted to run out of the liquid helium that has run through its veins, keeping its infrared detectors at frosty operating temperatures of just a few degrees above the coldest temperature possible, called absolute zero. The spacecraft, which is now in orbit around the sun more than 100-million kilometers (62-million miles) behind Earth, will heat up just a bit -- its instruments will warm up from - 456 degrees Fahrenheit (-271 Celsius) to - 404 degrees Fahrenheit (-242 Celsius). This is still way colder than an ice cube, which is about 32 degrees Fahrenheit. More importantly, it is still cold enough for some of Spitzer's infrared detectors to keep on probing the cosmos for at least two more years. If Spitzer could talk, here's how an interview with the observatory might go: Interviewer: It's cold in here. Spitzer: Sorry. Even though I'm warming up, I still need to be quite chilly for two of my infrared channels to continue working. Interviewer: Why do infrared telescopes need to be cold? Spitzer: Good question. Infrared light is produced by heat. So, engineers reduce my own heat to make sure that I'm measuring just the infrared light from the objects I'm studying. This is the same reason why I circle around the sun, far behind Earth, and why I have big sun shields -- to keep cool. Interviewer: Tell me, Spitzer, about what you consider to be your greatest discovery? Spitzer: Probably my work on exoplanets, which are planets that orbit stars other than our sun. I hate to brag, but I was the first telescope to see actual light from an exoplanet. I was also the first to split that light up into a spectrum. Oh, sorry, there I go again with the techie talk. Light is made up of lots of different wavelengths in the same way that a rainbow is made up of different colors. I was able to split an exoplanet's light up into its various infrared wavelengths. This spectral information teaches us about planets' atmospheres. Interviewer: What did you learn about the planets? Spitzer: For one thing, I learned that the hot gas exoplanets, called "hot Jupiters," are not all alike. Some are wild, with temperatures as hot as fire and almost as cold as ice. Others are more even-keeled. I also created the first temperature map of an exoplanet, and watched a storm of colossal proportions brewing across the face of one bizarre exoplanet – it has an orbit that swings in really close to its star and then back out to about where Earth sits in our solar system. Interviewer: You seem to really like planets. Spitzer: Well, you know, I wasn't even originally designed to see exoplanets! It was a complete surprise to me that I had this amazing ability. I can tell you that I do, and always will, have a thing for planetary disks. Because I have infrared eyes, I can see the warm and dusty planetary materials that swirl in disks around young stars. I can also see older disks littered with the remnants of planets. In fact, I've probably looked at thousands of disks so far. What's been fun is finding them around all sorts of oddball stars, such as those that are dead, doubled up as twins and even as small as planets. Bottom line is that the process of growing planets seems to happen quite easily all over the galaxy, and perhaps the universe. Interviewer: Does that mean aliens could be everywhere? Spitzer: I can't really give you a good answer for that. Yes, the studies of disks are showing us that rocky planets are common, but we don't know if the planets could have life. Also, keep in mind that, as of now, nobody has detected any planets that are just like Earth. These would be rocky worlds around stars like our sun that have the right temperature for lakes and oceans. That job will most likely fall to NASA's Kepler mission, which will begin hunting for them soon. Interviewer: Did you look at other objects besides disks and planets? Spitzer: Oh yes, certainly. I have looked at comets in our solar system, the farthest galaxies known, and everything in-between. I was really excited to find hundreds of hidden black holes billions of light-years away. Astronomers had known they were there because they shoot X-rays into space that can be detected as a diffuse glow. But the objects themselves were choked in dust. My infrared eyes, unlike your human eyes, can see through dust, so I was able to round up a lot of these missing black holes. Interviewer: Is there any other discovery you want to mention? Spitzer: There are too many to list, but I am particularly proud of this huge mosaic I took of a large swath of our Milky Way galaxy. It looks stunning when you print it out to poster size, and it's the best view ever of the bustling central portion of our galaxy. You see, the middle of the Milky Way is hopping with stars and dust. It's chaos, and visible-light cannot escape. These observations not only look cool, they also helped astronomers remap the structure of our galaxy. The new map shows just two spiral arms of stars instead of four as previously believed. How crazy is that! Interviewer: So what lies ahead? Spitzer: Well, I'm really looking forward to the warm mission, because now that I have just two infrared channels working, I have more time to look at larger chunks of space for longer periods of time. I can help astronomers answer some really important "big picture" questions, which we didn't have time for before. Interviewer: Can you list some specific projects you'll be working on? Spitzer: I plan to continue studying exoplanets, including new "hot Jupiters" that Kepler is expected to find. I will also refine estimates of the rate at which our local universe, or space, is expanding. And I will stare at the very distant universe, trying to see some of the farthest objects possible. Oh, and I am also going to survey thousands of asteroids in our neck of the solar system, and get the first real estimate of their size distribution. This will tell us approximately how often big asteroids might come close to Earth. Interviewer: That sounds scary. Spitzer: Actually, this information will help us prepare for them. And NASA tracks near-Earth objects diligently. More information can only help. Interviewer: Will you still take the pretty pictures? Spitzer: You think my pictures are pretty? Thank you! Yes, I will still snap a lot of pictures. For instance, I will continue to probe cloudy star-forming regions in our galaxy, which often make dramatic pictures. Interviewer: Anything else you'd like to add? Spitzer: My cool years have been more than I could ask for, and I look forward to more adventures to come. I'd also like to thank all of the scientists and engineers who have worked so hard to make my mission an ongoing success. And, if any of my fans out there want more info, they can go to www.spitzer.caltech.edu/spitzer . -end- From: subscription email

Serge 2009-05-06T14:47:50Z