Carrying a crew of seven and the Hubble Telescope, space shuttle Discovery fled to a safer, higher orbit Saturday to avoid a piece of space junk the size of a book.
The fragment of an exploded rocket would have come dangerously close to Discovery and the telescope anchored in its cargo bay had the pilots not steered out of the way.
Hours later, astronauts Mark Lee and Steven Smith went into open space to install three new Hubble parts, relatively small components requiring more hand-intensive work than the two previous nights of spacewalking.
NASA, meanwhile, was considering an emergency facelift for the middle-aged telescope, which has been in space for seven years.
Astronauts making the mission’s second spacewalk Friday night discovered a surprising number of cracks and tears in Hubble’s thin, outer insulation, as well as holes punched into the solar panels by micrometeoroids.
The National Aeronautics and Space Administration formed a team to assess the damage.
Spacewalk No. 3, on Saturday night, was already crowded with Hubble chores: the installation of a new computer switchboard, digital recorder and a flywheel assembly that helps aim the telescope.
Hubble got a bigger boost than planned Saturday.
A few hours after Discovery’s pilots steered the shuttle and the moored Hubble into a 2-mile-higher orbit to extend the lifetime of the telescope, they were ordered to go up an additional half-mile.
An 8-inch-square fragment of an exploded Pegasus rocket was due to pass within a half-mile of the shuttle and telescope, officials said, and Mission Control did not want to take any chances. The speed of the debris: 17,500 mph.
The Pegasus was launched in 1994 with a military research satellite, which ended up in the wrong orbit.
Fortunately, boosting Hubble on Saturday was part of NASA’s plan all along.
Like any orbiting object, the telescope gradually loses altitude because of gravity’s constant tug and friction from the outer atmosphere. The astronauts planned to raise Hubble an additional 2-1/2 miles over the next two nights, into a 375-mile-high orbit.
With the completion of Friday night’s 7-1/2-hour spacewalk, Discovery’s astronauts had finished installing Hubble’s most critical replacement parts, meeting NASA’s criteria for minimum mission success.
Joe Tanner and Gregory Harbaugh replaced a worn guidance sensor and failed data recorder on Hubble, and added an electronics package for the guidance sensor. They also spent a considerable amount of time surveying the 40-foot-long, power-generating solar panels.
They found too many holes in the panels to count.
NASA was more concerned about Hubble’s ripped, peeling insulation.
The fear is that flakes of the silver Teflon could drift near the telescope’s aperture and contaminate its sensitive optics.
MEMO: This sidebar appeared with the story: HIGH-SPEED DEBRIS The rocket fragment is moving at 17,500 mph. It was one of 8,014 orbiting objects being tracked by the U.S. Space Command on Saturday, most of it junk.
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