4 a.m. CDT Thursday, May 15, 2009
Mission Control Center, Houston, Texas
STS-125 MCC Status Report #08
Mission Specialists Mike Good and Mike Massimino will venture outside shuttle Atlantis today to complete the second of the mission’s five spacewalks. The crew awoke this morning at 3:31 a.m. CDT to “God of Wonders.” It was played for Good.

Today’s spacewalk will begin at 7:16 a.m. and is scheduled to last 6.5 hours. The first major task will be the replacement of all three of Hubble’s rate sensing units (RSUs). Each rate sensing unit contains two gyroscopes, which help the telescope point itself. The telescope is designed to operate on three of the six gyros, but today’s spacewalk will give Hubble all new units.

The second major task will be the replacement of the battery module in Bay 2 of the telescope. Each battery module weighs 460 pounds and contains three batteries. Each of the nickel hydrogen batteries weighs 125 pounds, and they provide power to the telescope when it passes into the night sky and the solar arrays are not exposed to the sun. All of the batteries on Hubble are original equipment, and they were only designed to operate for five years. The STS-125 crew also will install new batteries in Bay 3 of Hubble during the mission’s fifth and final spacewalk.

Commander Scott Altman and Mission Specialist Megan McArthur will perform an inspection of some of the shuttle’s heat shield tiles using the robotic arm. The teams on the ground weren’t able to get a full view of the tiles during Tuesday’s inspection. There are 40 tiles the crew will be examining, and those images will be downlinked to the teams in Houston for analysis. Today’s inspection is expected to take 45 minutes.

The last item on today’s schedule for the crew is the review of the procedures for tomorrow’s spacewalk, the third of the mission.

The crew will enter its sleep period at 7:31 p.m. and will awake at 3:31 a.m. The next status report will be issued at the end of the crew’s day or earlier if events warrant.

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