spacetoday.net: Shuttle astronauts wrap up final Hubble spacewalk

Posted: Fri, Mar 8, 2002, 5:52 PM ET (2252 GMT)
STS-109 EVA #5 (NASA)

Astronauts successfully completed their work on the Hubble Space Telescope Friday morning with a final spacewalk to install a new cooling unit for an instrument. Astronauts John Grunsfeld and Richard Linnehan spent seven hours and 20 minutes outside the shuttle Columbia Friday morning on the last of five spacewalks planned for the STS-109 mission. The astronauts installed a mechanical cooling unit on the telescope to be used by the NICMOS infrared camera. That camera, installed on Hubble in 1997, originally used a block of solid nitrogen to cool its detectors, but a thermal leak caused the nitrogen to run out in 1999, forcing NASA to shut down the instrument. Astronomers hope that the new mechanical cooling system should cool down the instrument enough to work again, but will not know for several weeks if it works. With the successful completion of all five spacewalks, the shuttle crew is finished with its repairs and upgrades to Hubble, and will release the spacecraft Saturday at 5:03 am EST (1003 GMT). Columbia is scheduled to land at the Kennedy Space Center Tuesday at 4:35 am EST (0935 GMT).