Spacewalk #3 ...Part 2

Well, Hubble continues to surprise. The hardest job of the mission, repairing the Advanced Camera for Surveys (ACS), has gone amazingly well.

Working in extremely tight quarters, around a corner from his work site and partially out of view, John Grunsfeld has managed to complete the first actual instrument repair ever done in space.

First he cut through a metal grid and removed it, avoiding the sharp edges, and exposed a cover plate held on by 32 tiny screws. Next he partially loosened all the screws, then installed the Fastener Capture Plate, then removed all the screws.

After two years of worry, amazingly not a single screw stuck, or broke, or was stripped. And, captured inside the special tool, nothing floated loose inside Hubble where it could have damaged the telescope.
John then removed four electronic circuit boards, installed a new power supply box, and connected all the necessary wiring.

So far the new Cosmic Origins Spectrograph has been powered up and passed its electrical "aliveness test." A similar test still remains to be done on ACS.

After two difficult days that ran long (according to Dr. Matt Mountain, Director of the Space Telescope Science Institute, yesterday's spacewalk was the eighth longest in history), so far today's spacewalk is a stunning success--Grunsfeld is actually nearly two hours ahead of schedule, after completing a repair no one was certain was even possible.

And as I'm writing this, they just now announced that ACS, too, has passed its aliveness test.

All that remains is closing the doors (which have been troublesome before). Barring a problem there, it looks like Day 3 will turn out to be a huge success. After the past two days, everyone here was exhausted and dreading all that might go wrong today--this should give them all a huge lift.
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