Press Release

UA Astronomers’ Hopes Ride with Astronauts on 5th Space Walk

By SpaceRef Editor
March 4, 2002
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Astronauts aboard space shuttle Columbia on an 11-day repair mission to the
Hubble Space Telescope (HST)successfully completed the first of five planned
spacewalks early this morning.

The University of Arizona has a lot riding on the current shuttle mission.

In a planned fifth and final spacewalk this week, Columbia’s astronauts will
endeavor to repair the UA instrument that gives NASA’s premier space
telescope infrared vision. If the late Thursday night – early Friday
spacewalk succeeds, astronomers will again see the universe with what some
have dubbed “The Incredibly Cool Machine,” the infrared camera and
spectrometer NICMOS.

NICMOS, or the Near Infrared Camera and Multi-Object Spectrometer, is a $100
million space instrument conceived, designed and built by the University of
Arizona under contract from the NASA Goddard Space Flight Center. The effort
was spearheaded by UA astronomy Professor Rodger I. Thompson, principal
investigator for NICMOS.

Thompson and his colleagues at the UA and other universities first proposed
NICMOS for the Hubble Space Telescope in 1984. UA team members include John
Hill, Frank Low, Donald McCarthy Jr., Marcia Rieke (deputy principal
investigator), Glenn Schneider, and Erick Young.

After NICMOS was installed onboard the HST during the second servicing
mission in February 1997, it made observations of newly forming stars and
regions containing the farthest and faintest galaxies ever imagined. It
revealed as never before planets in our solar system and possible planets
beyond. It achieved nearly all its scientific objectives before 1999, when
coolant necessary to chill NICMOS’ infrared detectors was depleted.

Thompson said perhaps NICMOS’ two most outstanding observations so far have
been the NICMOS Hubble Deep Field — views of the most distant galaxies ever
seen, and observations of a supernova in that field which confirmed that the
universe is accelerating, rather than slowing down, as it expands.

NASA developed a new mechanical cryocooler that will cool the NICMOS to
temperatures around 75-86 degrees Kelvin (between minus 198 degrees and
minus 187 degrees Celsius, or minus 325 degrees and minus 304 degrees
Fahrenheit) so its infrared detectors will again be sensitive to infrared
wavelengths, or heat.

“The instrument should actually perform better than before since we can
adjust the temperature to the best operation temperature,” Thompson said.
“With solid nitrogen (the previous coolant), we had to run cooler than we
wanted to.”

How long can this cooling system last?

“Indefinitely,” Thompson said. “It is a mechanical cooler rather than a
cooler that depends on cryogen. It is the difference between a refrigerator
and an old fashioned ice box. “

***(EDITORS: Thompson will be at NASA’s Johnson Space Center in Houston
tomorrow through Saturday, but will return phone calls in his voicemail at
520-621-6527.)

SpaceRef staff editor.