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 finds 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 actual 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,
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.
For more information about Spitzer, visit: http://www.nasa.gov/spitzer
and http://www.spitzer.caltech.edu/spitzer.
See Also:
Spitzer Space Telescope podcast
Spitzer Space Telescope Videos
US $88.66
