NASA's Spitzer Space Telescope has operated at -456 degrees Fahrenheit (-271 Celsius) for more than five-and-a-half years, probing the cosmos with its infrared eye. But it’s about to run out of the liquid helium needed to chill some of its instruments to operating temperatures.
A Spitzer view of the Milky Way (NASA image)
When that happens—within a week of May 12, NASA predicts—the Spitzer will begin a new, “warm” mission, still super-cold at -404 degrees Fahrenheit (-242 Celsius), with two channels of one of its three instruments still working at full capacity.
"We like to think of Spitzer as being reborn," said Robert Wilson, Spitzer project manager at NASA's Jet Propulsion Laboratory in Pasadena. "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."
To bring home the development in an easy-to-understand format, NASA has the text of a mock interview with the telescope online here.
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 less than 3 degrees above absolute zero.
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, NASA said.
The telescope's two shortest-wavelength detectors in its infrared array camera will continue to function perfectly and will 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."
The Spitzer telescope gets interviewed. (NASA illustration)
Among the project’s achievements: In 2005, Spitzer detected the first actual photons from an exoplanet, or a planet-like object outside the Solar System. 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."
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, Calif. Lockheed Martin Space Systems in Denver, and Ball Aerospace & Technology 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.
Spitzer Telescope www.nasa.gov/spitzer and www.spitzer.caltech.edu/spitzer