Amazing Effort Does Not Come Without Complications
STS-125 mission specialists Mike Massimino and Mike Good
completed the mission’s fourth spacewalk Sunday at 5:47 p.m.
EDT. The spacewalkers continued repairs and improvements to the
Space Telescope Imaging Spectrograph (STIS) that will extend the
Hubble’s life into the next decade.
In the sixth longest spacewalk in history, Astronauts Mike
Massimino and Michael Good tackled the intricate task of removing
and capturing 111 screws to be able to revive the Hubble Space
Telescope’s two-dimensional spectroscopy capability.
In the 8 hour, 2 minute spacewalk, Massimino and Good repaired
the Space Telescope Imaging Spectrograph (STIS) by replacing a
power supply board. STIS, installed on the Hubble Space Telescope
in 1997, stopped working in August 2004 due to a power supply
failure and was in a “safe mode.”
Though the removal of the many screws was expected to be
difficult, a handrail gave Good and Massimino trouble. The handrail
was obstructing the path of a fastener capture plate and one
stripped bolt prevented it from coming free. Massimino followed
steps developed quickly at the Goddard Spaceflight Center to
carefully bend and break the handrail free so that the fastener
capture plate could be installed. At about three hours into the
spacewalk, Massimino broke the handrail free allowing the
spacewalkers to proceed with the day’s tasks.
The initial aliveness test reported the STIS as working
properly. The initial functional test was ended when the telescope
put itself into “safe mode,” having reached a low
thermal limit. The STIS is believed to be in good shape. Ground
controllers will start the functional tests over again, once the
telescope reaches a good temperature.
The STIS separates light into its component colors to reveal
information about the chemical content, temperature and motion of
planets, comets, stars, interstellar gas and galaxies. The
information it can provide will help scientists better understand
the physical properties of the material universe – putting
the physics in astrophysics.
Massimino and Good were unable to get to the installation of the
New Outer Blanket Layer (NOBL) on the outside of the
telescope’s bay 8. Mission managers have asked Mission
Specialists John Grunsfeld and Andrew Fuestel to add the
installation of a partial set of blankets on bay 8 during
Monday’s spacewalk. If time permits, the two may get to
install the full set.
The crew was due to wake up Monday at 0431 to conduct the fifth
and final spacewalk of the mission.
NASA has updated their plans for the Fifth spacewalk, "Our goal
is to get the spacewalk done on time, which is scheduled to last 5
hours, 45 minutes. Batteries and the Fine Guidance Sensor tasks are
our priorities for tomorrow's spacewalk. We will make a real time
call where we are in the timeline after those tasks are complete on
the go forward plan for the Bay 5 & 8 New Outer Blanket Layer
installation tasks. For the baseline plan, we would do a partial
Bay 8 and then go to the other side and do a full Bay 5."