May 19, 2009
NASA's Spitzer Telescope Warms Up To New Career
 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, Sheldon Kalnitsky, 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.
Posted at 02:34 am by sarahbaltic
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