Astronaut Andrew Feustel, tethered to the end of the remote manipulator system arm (left), navigates near the Hubble Space Telescope, during the mission's third spacewalk. Astronaut John Grunsfeld signals to his crewmate from just a few feet away.
Credit: NASA
HOUSTON: Two astronauts had to overcome frustrating obstacles, including snapping off a handrail, during the fourth spacewalk on the final mission to service the Hubble Space Telescope.
The fourth spacewalk of five, completed by astronauts Mike Massimino and Mike Good, was considered by NASA to be the most intricate spacewalk of the mission.
The two men were forced to contend with obstacles that required extra doses of ingenuity, patience and elbow grease and stretched their activities to just over eight hours, returning to the shuttle Atlantis Sunday at 5:47 pm EDT (Monday, 7:47 am Australian EST).
Massimino and Good focussed all of their efforts on the Space Telescope Imaging Spectrograph (STIS), which was installed in the telescope by shuttle astronauts in 1997 but has been in ‘safe mode’ since a power failure in 2004.
Frustrating obstacles
Prior to the failure, science with the STIS constituted about 30% of all Hubble observations. Its achievements have included weighing several dozen supermassive black holes at the cores of galaxies.
"Oh, for Pete's sake," Massimino complained when the battery-operated ratchet he was using lost power. Later, the veteran astronaut cursed as he wrestled to discard the cover plate he'd pulled from the STIS into a storage bag.
In order to replace a failed power converter, Massimino and Good had to replace an internal circuit card. The extraction required Massimino to remove a protective cover secured by 111 small screws using an arsenal of custom-made hand tools.
But access to the cover and the many tiny fasteners was obstructed by a handrail that had to be removed first. The rail was secured by four bolts, one of them badly stripped.
After several failed attempts to turn the bolt with wrenches, Massimino offered to snap the handrail off using some old-fashioned muscle. "Okay, here we go," said Massimino as he broke away the fixture. "Awesome," responded Mission Control.
Third spacewalk "partial success"
The spectrograph quickly passed an electrical test, but Hubble engineers planned to spend their Sunday night (Monday morning in Australia) conducting a more exhaustive test of the instrument.
NASA said efforts on the previous day to revive a second Hubble instrument, the Advanced Camera for Surveys, was a partial success. The repairs, performed by John Grunsfield and Drew Feustel, recovered two of three internal imagers.
"At this point, we are feeling really good," said Preston Burch, NASA's Hubble program manager, on Sunday. "Hubble has reached a new high in terms of capabilities. We have also made huge strides in terms of restoring the health of the observatory."
