Astronauts John Grunsfeld (left) and Andrew Feustel, both STS-125 mission specialists, participate in the mission’s fifth and final ever session of extravehicular activity
(EVA) to repair and upgrade the Hubble Space Telescope. During the seven-hour and two-minute spacewalk, Grunsfeld and Feustel installed a battery group replacement,
removed and replaced a Fine Guidance Sensor and three thermal blankets (NOBL) protecting Hubble’s electronics. Credit: NASA
space suit. Fortunately he managed
to break and remove it safely some
three hours into the EVA.
As it turned out, the fastener-capture plate that had been so cleverly
designed on the ground proved to
be of great use and the screws were
removed ok now access had been
gained. Another issue then occurred
when power to one of Massimino’s
tools failed and a spare had to be
retrieved. Whilst doing this Massimino
took time to re charge his suits Oxygen supply.
This issue had taken up valuable
EVA time and by now the two space
walkers were behind schedule so
ground controllers decided that
the task of replacing old thermal
blankets with the New Outer Blanket
Layers (NOBL) onto Bay 8 should be
postponed and moved into another
EVA period.
It was by now Day 8 of Atlantis’s
scheduled 11-day mission and the
EVA 5 was slated to be the last. It fell
to Grunsfeld and Feustel so finish up
any last chores.
Firstly they swapped out the battery module from Bay 3 and then replaced it with a second battery. They
also did the task of replacing the Fine
Guidance Sensor 3 on the telescope.
Hubble has three of these sensors
which help it to point itself. Two of
the sensors are used to point the
telescope and then lock it onto any
astronomical target and the third
sensor is then used to take positional
measurements known as astrometry.
All three are essential for Hubble.
Because Grunsfeld and Feustel
had completed these tasks ahead of
schedule they were able to replace
three sets of the NOBLs including the
ones that Massimino and Good had
run out of time to replace on EVA 4.
All that remained were the four
months of checking out and calibrating the instruments before scientific
observations could begin again.
Hubble was alive again!
Releasing Hubble
Day 9 was slated to be the day
that the crew of Atlantis would release Mr. Hubble’s telescope back
into orbit and bid farewell. Megan
McArthur captured Hubble once
more with the robotic arm and
slowly, carefully, methodically began
the process of extracting Hubble
from the payload bay and back into
Earth’s orbit.
Ground teams worked through
several check lists and finally the
command came for Megan to
release Hubble back into space.
Pilot Gregory Johnson performed a
small engine burn and slowly Atlantis
moved away from the telescope.
STS-125’s mission to Hubble was finished.
And it was with that the STS-125
Commander Altman commented
“Hubble has been released, it’s
safely back on its journey of exploration as we begin steps to conclude
ours” he concluded with “And now
Hubble can continue on its own, exploring the cosmos, and bringing it
home to us as we head for home in
a few days. Thank you”