Astronauts Michael Good (left) and Mike Massimino, both STS-125 mission specialists, participate in the mission’s fourth session of extravehicular activity (EVA) as work
continues to refurbish and upgrade the Hubble Space Telescope. During the eight-hour, two-minute spacewalk, Massimino and Good continued repairs and improvements
to the Space Telescope Imaging Spectrograph (STIS) that will extend the Hubble’s life. Credit: NASA
operating on one remaining channel
a repair attempt on this EVA would
try to reinstate the Wide Field Channel. It was this channel that was responsible for 70% of the pre 2007 ACS
Science and importantly it is hoped
that once repaired it could answer
some of the questions relating to
the mysterious origins of Dark Matter
and Dark Energy. With the ACS Wide
Field Camera 3 (WFC-3) combined
they would form a formidable team
of instruments in the pursuit of those
answers. The problem however for
the ACS was that it never had been
designed to be repaired in space!
Using the specially designed tools
from ATK, the spacewalkers carefully
removed panels in the unit for access and slowly and methodically replaced the camera’s electronic circuit boards and power supply. After
a ground check the ACS seemed to
working O ,