Spaceflight Now: Fixing Hubble

PAGE 3
Shuttle Discovery poised for urgent Hubble repair
BY WILLIAM HARWOOD
Posted: Dec. 14, 1999


The crew of STS-103 from the left, astronauts Michael Foale, Claude Nicollier, Scott Kelly, Curt Brown, Jean-Francois Clervoy, John Grunsfeld and Steve Smith. Photo: NASA/JSC

Joining Smith, Grunsfeld, Foale and Nicollier -- all shuttle veterans -- for the for the 10-day flight will be commander Curt Brown, pilot Scott Kelly and flight engineer Jean-Francois Clervoy, a European Space Agency astronaut who will operate the shuttle's robot arm during all four spacewalks.

NASA originally targeted launch for Oct. 14, but a short circuit during a July shuttle flight prompted shuttle managers to order fleet-wide wiring inspections that uncovered scores of defects. The Hubble mission slipped into November and ultimately, December.

In the meantime, a fourth gyroscope failed aboard the telescope, putting the observatory into protective safe mode. With the two remaining gyros off line, Hubble slowly rotates as it orbits Earth, keeping its solar arrays perpendicular to the sun's rays to provide good battery charging.

Backup gyros will be activated just before Discovery gets to the telescope to provide stability. But Hubble will not be in the precise orientation the astronauts were expecting.

"The rendezvous will take place exactly the same way [we had planned] except when we arrive at the Hubble, we'll probably have to do a fly around maneuver to align the Hubble in the correct orientation for grapple," said Brown.

  Clervoy
Jean-Francois Clervoy will pluck the telescope from orbit with the shuttle's robot arm. The European Space Agency astronaut is pictured here during preflight training at the Kennedy Space Center. Photo: NASA/KSC
 
Clervoy, who will be responsible for actually grabbing Hubble with Discovery's robot arm, said he is unconcerned.

"We trained to exactly the scenario we have in orbit and Curt has always been able to stabilize the orbiter very, very steady relative to the telescope even with the maximum drift rates we can expect," he said. "It's an easy task to grapple it."

It will take Discovery two days to catch up with the 24,300-pound (11,022-kilogram) Hubble, orbiting at an altitude of about 380 miles (600 kilometers). Clervoy, operating Discovery's 50-foot-long (15-meter) robot arm, will capture the telescope by snaring a grapple fixture on its side. He then will mount the 43-foot-long (13-meter-long) observatory vertically atop a turntable-like work platform at the rear of the shuttle's cargo bay. The first spacewalk is scheduled to get underway that night.

"I feel better about it now," Foale quipped after the fourth gyro failure. "Because now we really are going to put the telescope right, get it back into service producing science. Now we're not up against that adage of 'if it isn't broke, don't fix it.' So I think we're in good shape here. We're not going to do anything to change out plan, but the justification is proven to go do this mission."

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Explore the Net
NASA Human Spaceflight - Space agency Web site dedicated to International Space Station and space shuttle programs.

Press kit - Official STS-103 mission press kit.

Shuttle Media Reference Guide - Complete in-depth look at space shuttle systems and facilities.

Shuttle Countdown Online - NASA Kennedy Space Center site with pre-launch information.

Hubble Space Telescope - Home page of NASA's first Great Observatory.

HST Servicing Mission 3A - NASA site focused on this servicing mission of Hubble.

European Space Agency - partner in HST program and has two astronauts flying on STS-103.

United Space Alliance - prime contractor responsible for daily shuttle processing work.

Thiokol - Manufactures the shuttle's solid rocket boosters.

Rocketdyne - Division of Boeing that builds shuttle main engines.

Lockheed Martin - Corporation that builds the external fuel tank.