Live in Orbit: Different gyros fit fine

Success!

After failed attempts to install a second pair of gyroscopes into the Hubble Space Telescope, Atlantis spacewalkers easily fit an alternate set into the same slot.

"I've definitely got it," astronaut Mike Good said after bolting a second Rate Sensor Unit into place.

Fellow spacewalker Mike Massimino and mission specialist John Grunsfeld, guiding the spacewalk from inside shuttle Atlantis, cheered.

Grunsfeld told ground controllers he was "ecstatically able to report" success with the second unit, which was intended to be installed in a different location.

The original unit wouldn't fit properly in its slot, so the spacewalkers will now try it in the third and final slot.

Each unit contains two newly designed gyroscopes that allow the telescope to point properly.

If the final unit can't be installed again, the crew can try a backup of the older design.

The telescope only needs two gyroscopes to function, but an entirely new set of six would likely give it the longest life possible, at least five to 10 more years.

Still, the installation of a second set fulfills another of the "minimum mission success" criteria. Two more were achieved yesterday: installation of the Wide Field Camera 3 and a new data handler.

The mission's second of five planned spacewalks is nearly four hours old.

It is scheduled to last six-and-a-half hours, hopefully including enough time to install a new set of batteries after completing work on the gyroscopes.