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May 17, 2009

US Astronauts Set for 4th Spacewalk for Hubble Repairs
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Mike Good and Mike Massimino are scheduled to replace the power supply
board for a powerful instrument that allows NASA to identify black holes
and monitor galaxies 
U.S. astronauts are set undertake their fourth in a series of five
spacewalks Sunday to repair the Hubble Space Telescope. Astronaut
Michael Good works with the Hubble Space Telescope in the cargo bay of
the earth-orbiting space shuttle Atlantis, 15 May 2009Astronauts Mike
Good and Mike Massimino are scheduled to replace the power supply board
for a powerful instrument, the Space Telescope Imaging Spectrograph,
that allows NASA to identify black holes and monitor galaxies. It has
not worked since 2004. The astronauts will also install extra insulation
panels on the telescope, to help protect it from rapid temperature
changes as it orbits from very hot sun to very cold night. Saturday,
astronauts John Grunsfeld and Drew Feustel replaced an optics package on
the telescope with a sophisticated instrument, the Cosmic Origins
Spectrograph, used to capture images that will help explain how planets,
stars and galaxies are formed. The five spacewalks are intended to
upgrade the 19 year!
 -old telescope and extend its life for at least five more years. The
mission is more dangerous than others because the telescope is sharing
an orbit with debris left behind by satellite collisions and rocket
launches. The astronauts are further challenged because they can only
work with the supplies they are able to carry with them on the shuttle.
In missions to the International Space Station, astronauts have enough
support on the station to last up to three months. On Friday, two
shuttle crew members spent nearly eight hours working on the giant
telescope. The U.S. space agency NASA said it was the eighth longest
spacewalk in history. The astronauts replaced two large battery modules
and worked on installing new gyroscopes that help the telescope point in
the right direction. A day earlier, a new camera was installed that will
allow the telescope to take detailed photos using a wide range of
colors. Some information for this report was provided by AFP.


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