NASA's WISE Space Telescope Jettisons Its Cover

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Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin@jpl.nasa.gov

News release: 2009-206 Dec. 29, 2009

NASA's WISE Space Telescope Jettisons Its Cover

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2009-206&cid=release_2009-206

NASA's recently launched Wide-Field Infrared Survey Explorer opened its eyes to the
starry sky today, after ejecting its protective cover.

Engineers and scientists say the maneuver went off without a hitch, and everything is
working properly. The mission's "first-light" images of the sky will be released to the
public in about a month, after the telescope has been fully calibrated.

"The cover floated away as we planned," said William Irace, the mission's project
manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "Our detectors are
soaking up starlight for the first time."

WISE will perform the most detailed infrared survey of the entire sky to date. Its millions
of images will expose the dark side of the cosmos -- objects, such as asteroids, stars and
galaxies, that are too cool or dusty to be seen with visible light. The telescope will survey
the sky one-and-a-half times in nine months, ending its primary mission when the coolant
it needs to see infrared light evaporates away.

WISE launched on Dec. 14 from Vandenberg Air Force Base in California. Once it was
thoroughly checked out in space, it was ready to "flip its lid."

The cover served as the top to a Thermos-like bottle that chilled the instrument -- a 40-
centimeter (16-inch) telescope and four infrared detector arrays with one million pixels
each. The instrument must be maintained at frosty temperatures, as cold as below 8
Kelvin (minus 447 degrees Fahrenheit), to prevent it from picking up its own heat, or
infrared, glow. The cover kept everything cool on the ground by sealing a vacuum space
into the instrument chamber. In the same way that Thermos bottles use thin vacuum layers
to keep your coffee warm or iced tea cold, the vacuum space inside WISE stopped heat
from getting in. Now, space itself will provide the instrument with an even better vacuum
than before.

The cover also protected the instrument from stray sunlight and extra heat during launch.

At about 2:30 p.m. PST (5:30 p.m. PST), Dec. 29, engineers sent a command to fire
pyrotechnic devices that released nuts holding the cover in place. Three springs were then
free to push the cover away and into an orbit closer to Earth than that of the spacecraft.

Scientists and engineers are now busy adjusting the rate of the spacecraft to match the
rate of a scanning mirror. To take still images on the sky as it orbits around Earth, WISE
will use a scan mirror to counteract its motion. Light from the moving telescope's primary
miror will be focused onto the scan mirror, which will move in the opposite direction at
the same rate. This allows the mission to take "freeze-frame" snapshots of the sky every
11 seconds. That's about 7,500 images a day.

"It's wonderful to end the year with open WISE eyes," said Peter Eisenhardt, the
mission's project scientist at JPL. "Now we can synch WISE up to our scan mirror and
get on with the business of exploring the infrared universe."

WISE is scheduled to begin its survey of the infrared heavens in mid-January of 2010.

JPL manages the Wide-field Infrared Survey Explorer for NASA's Science Mission
Directorate, Washington. The principal investigator, Edward Wright, is at UCLA. The
mission was competitively selected under NASA's Explorers Program managed by the
Goddard Space Flight Center, Greenbelt, Md. The science instrument was built by the
Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by Ball
Aerospace & Technologies Corp., Boulder, Colo. Science operations and data processing
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://www.nasa.gov/wise and http://wise.astro.ucla.edu .

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