Glitches bedevil Hubble repairs

HOUSTON (AP) — Spacewalkers’ specially designed tools couldn’t dislodge a balky bolt interfering with repairs Sunday at the Hubble Space Telescope. So they took an approach more familiar to people puttering around down on Earth: brute force.

And it worked. But it set spacewalkers so far behind that they couldn’t get all their tasks done.

Atlantis astronaut Michael Massimino couldn’t remove one bolt attaching a hand rail to the outside of a scientific instrument he needed to fix. The rail had to be removed or at least bent out of the way.

That was only the beginning of a hard-luck day. The balky bolt and other tiny problems put spacewalkers so far behind schedule that they had to abandon the second part of their spacewalk: replacing some worn insulation on the telescope.

Still, the marathon spacewalk by Massimino and Michael Good took so long — just more than eight hours — that it was the sixth-longest U.S. spacewalk and a few minutes longer than the one Friday.

When several tries with different expensive tools couldn’t remove the stripped-out bolt, Mission Control in Houston told Massimino to go for the less precise yank.

At Goddard Space Flight Center in Maryland, engineers twice tested that pull on a mock-up before Massimino was told to use his muscles.

“You hope you don’t get to the point where you just close your eyes and pull and hope nothing happens,” said James Cooper, the Goddard mechanical systems manager for the repair mission. “But we had run out of other options.”

Astronauts were careful to tape pieces so they wouldn’t fly away and become potential missiles.

And while Atlantis was out of video contact 350 miles above Earth, controllers in Houston could only listen as Massimino took a breath and pulled.

After a second of silence, Massimino calmly said: “Disposal bag, please.”

After nearly two hours of work on the balky bolt, astronauts went back to the plan to bring the Space Telescope Imaging Spectrograph back from the dead.

Early test results show the spectrograph, disabled by a power failure five years ago, was brought back to life. But when further tests started, the instrument put itself into “safe mode” because of temperature problems.

Three of the four Hubble spacewalks so far this mission have been delayed by niggling problems, like stubborn bolts and objects that wouldn’t fit. A fifth and final spacewalk is set for today.

Massimino’s run of bad luck only continued. While trying to install a special plate to remove 111 tiny screws that held the instrument cover in place, a tool’s battery died. It took more than half an hour for him to go back to the shuttle, swap out batteries and recharge his oxygen supply.

By the time Massimino replaced the internal electronics power supply card in the spectrograph, it was just about the originally scheduled time for the end of the spacewalk. And more than 90 minutes of clean up and close-out work remained.

So spacewalk coordinators on the ground decided that the second part of Sunday’s task, the insulation, had to be put off until today, if possible.

All the work may not get done today, but at least part will be attempted, Mission Control said.