Even in Space, an Old-Fashioned Fix
Just give it a whack. Sometimes, it seems, even in the highest tech circles, there is no substitute for good old brute force.
And so the question aboard the space shuttle Atlantis Sunday came down to whether Michael Massimino would rock a handrail back and forth first to fatigue a stripped bolt that was stubbornly holding the handrail on the Hubble Space Telescope — or just give it a big yank to break it and the bolt off.
Beyond the rail were 111 screws. Beyond the 111 screws were the internal electronics of Hubble’s Space Telescope Imaging Spectrograph, or STIS, the intended object of “brain surgery” on the fourth of five days of spacewalks intended to repair and upgrade the space telescope
The spectrograph, which has been used to measure the masses of giant black holes in galactic centers and to identify the constituents in the atmosphere of a planet orbiting another star, shut down in 2004 because of a short circuit in its power supply. It was not designed to be opened up and operated on in space. Nevertheless, for the past three years engineers and astronauts have studied and rehearsed a procedure to break into the instrument, capturing all those screws, and fix a broken power supply.
But first the spacewalkers, Dr. Massimino and Mike Good, had to get the handrail off.
It was the third of four spacewalks in this mission, the last to the 19-year-old telescope, to be stymied by low-tech problems like bad bolts only to have the more delicate tricky jobs, like Saturday’s repair of the Advanced Camera for Surveys, go smoothly.
Three of the bolts holding the handle on came off easily, but Dr. Massimino could not get traction with his drill on the fourth bolt head. After fussing with the bolt and then retrieving a new sharper drill bit from the airlock, he asked, “What’s Plan C?”
After a discussion about which way to apply tape to keep the broken bits of bolt from flying off into space or the telescope, and a review of the yanking procedures led by Commander Scott Altman, Dr. Massimino allowed that he would probably rock the rail back and forth once and then go for broke. As it happened, the shuttle had passed out of television range of mission control and an interplanetary audience.
“It’s off,” Dr. Massimino reported.
Adam Riess, who was watching on ASA TV and is a heavy Hubble user at the Space Telescope Science Institute and Johns Hopkins University, wrote in an e-mail message: “We always joke that they wait until they are out of TV view to use the hammers and crowbars . . . I guess they really do!
”The astronauts struggled to get back to their script, finally completing the repair about two hours behind schedule. Informed that the spectrograph had passed an initial “aliveness test,” whoops and cheers could be heard from the entire Atlantis crew.
Dr. Massimino asked the robot arm operator, Megan McArthur, to move him up a couple of feet.
Dr. McArthur replied, “For you, anything.”
There was slightly different news from the ground about Saturday’s repair, which, engineers reported after overnight tests, was not quite as successful as they had hoped. The on-orbit “brain surgery” restored the camera’s ability to take wide-field images but so far has failed to restore the ability to take high-resolution pictures.
Because the wide-field channel of the advanced camera is overwhelmingly the favorite of astronomers, the mission engineers still consider the operation an enormous success.
Dr. Riess, who has used the advanced camera to study the weird, so-called dark energythat seems to be accelerating the expansion of the universe, said, “I would consider it an unmitigated success if we do get only the wide-field channel back on-line.”
No comments:
Post a Comment