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Feature June 10, 2009
WISE Mission Assembled and Preparing for Launch
PASADENA, Calif. -- NASA's Wide-field Infrared Survey Explorer, or WISE, has
been assembled and is undergoing final preparations for a planned Nov. 1
launch from Vandenberg Air Force Base, Calif.
The mission will survey the entire sky at infrared wavelengths, creating a
cosmic clearinghouse of hundreds of millions of objects -- everything from
the most luminous galaxies, to the nearest stars, to dark and potentially
hazardous asteroids. The survey will be the most detailed to date in
infrared light, with a sensitivity hundreds of times better than that of its
predecessor, the Infrared Astronomical Satellite.
"Most of the sky has never been imaged at these infrared wavelengths with
this kind of sensitivity," said Edward Wright, the mission's principal
investigator at UCLA. "We are sure to find many surprises."
On May 17, the mission's science instrument was delivered to Ball Aerospace
& Technologies Corp. in Boulder, Colo., where it was attached to the
spacecraft, built by Ball. The assembled unit was then blasted by sound to
simulate the effects of launch. Tests for electronic "noise" in the
detectors will be performed next.
The science instrument is a 40-centimeter (16-inch) telescope with four
infrared cameras. A cryostat, or cooler, uses frozen hydrogen to chill the
sensitive megapixel infrared detectors down to seven Kelvin (minus 447
degrees Fahrenheit). The instrument was built by Space Dynamics Laboratory
in Logan, Utah.
Among expected finds from WISE are hundreds of thousands of asteroids in our
solar system's asteroid belt, and hundreds of additional asteroids that come
near Earth. Many asteroids have gone undetected because they don't reflect
much visible light, but their heat makes them glow in infrared light that
WISE can see. By cataloguing the objects, the mission will provide better
estimates of their sizes, a critical step for assessing the risk associated
with those that might impact Earth.
"We know that asteroids occasionally hit Earth, and we'd like to have a
better idea of how many there are and their sizes," said Amy Mainzer of
NASA's Jet Propulsion Laboratory, Pasadena, Calif., the mission's deputy
project scientist. "Whether they are dark or shiny, they all emit infrared
light. They can't hide from WISE."
The mission is also expected to find the coldest stars -- dim orbs called
brown dwarfs that are too small to have ignited like our sun. Brown dwarfs
are littered throughout our galaxy, but because they are so cool, they are
often too faint to see in visible light. The infrared detectors on WISE will
pick up the glow of roughly 1,000 brown dwarfs in our galaxy, including
those coldest and closest to our solar system. In fact, astronomers say the
mission could find a brown dwarf closer to us than the nearest known star,
Proxima Centauri, located approximately 4 light-years away.
"We've been learning that brown dwarfs may have planets, so it's possible
we'll find the closest planetary systems," said Peter Eisenhardt, the
mission's project scientist at JPL. "We should also find many hundreds of
brown dwarfs colder than 480 degrees Celsius (900 degrees Fahrenheit), a
group that as of now has only nine known members."
In addition, the survey will reveal the universe's most luminous galaxies
seen long ago in the dusty throes of their formation, disks of
planet-forming material around stars, and other cosmic goodies. The
observations will guide other infrared telescopes to the most interesting
objects for follow-up studies. For example, NASA's Spitzer Space Telescope,
the Herschel observatory just launched by ESA with significant NASA
participation, and NASA's upcoming James Webb Space Telescope will direct
their gaze at objects uncovered by WISE.
WISE will lift off from Vandenberg aboard a United Launch Alliance Delta II
rocket. It will orbit Earth, mapping the entire sky in six months after a
one-month checkout period. Its frozen hydrogen is expected to last several
months longer, allowing WISE to map much of the sky a second time and see
what has changed.
JPL manages the Wide-field Infrared Survey Explorer for NASA's Science
Mission Directorate. The mission's principal investigator, Edward Wright, is
at UCLA. The mission was developed under NASA's Explorer Program managed by
the Goddard Space Flight Center, Greenbelt, Md. The science instrument was
built by the Space Dynamics Laboratory and the spacecraft was built by Ball
Aerospace & Technologies Corp. Science operations and data processing will
take place at the Infrared Processing and Analysis Center at the California
Institute of Technology in Pasadena. Caltech manages JPL for NASA.
More information is online at http://wise.ssl.berkeley.edu/mission.html .
The Infrared Astronomical Satellite, launched in 1983, was a joint mission
between NASA, the United Kingdom and the Netherlands.
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