STS-125/HST SM-4 Status Report No. 12 (Forwarded)

STS-125 MCC Status Report #12
Mission Control Center, Houston, Texas
Sunday, May 17, 2009, 5 a.m. CDT

The crew of Atlantis is preparing for the fourth spacewalk of the mission,
which will begin today at 8:16 a.m. CDT. The crew awoke at 4:31 a.m. to "New
York State of Mind" performed by Billy Joel. The song was played for Mission
Specialist Mike Massimino.

Massimino and Mission Specialist Mike Good will focus on repairing the Space
Telescope Imaging Spectrograph (STIS) today. STIS was installed on the
Hubble Space Telescope during the second servicing mission in 1997. STIS
stopped functioning in August 2004 due to a power supply failure and is
currently in a "safe mode."

Just like on the Advanced Camera for Surveys (ACS), Good and Massimino will
overlay a fastener capture plate over the top of an access panel on the
STIS. But this time, the astronauts will have to loosen 111 screws in order
to remove the panel. Once repaired, the STIS will work in tandem with the
Cosmic Origins Spectrograph by allowing Hubble to see a full range spectrum.
Each of the instruments will back each other up while offering unique
capabilities to study black holes, stars and planets around other stars.

Massimino and Good also will install a New Outer Blanket Layer (NOBL) on the
outside of bay 8 on the telescope. This is a stainless steel cover that
protects the telescope from the extreme environment of space by providing
thermal protection for the equipment bays. The existing insulation has
degraded over time.

The crew's sleep period will begin at 8:31 p.m., and the crew is due to wake
up tomorrow at 4:31 a.m. and will conduct the fifth and final spacewalk of
the mission. The next status report will be issued at the end of the crew's
day, or earlier if events warrant.