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Spacewalkers get to work on Hubble tuneup
Instrument upgrade means better vision
February 14, 1997
Web posted at: 5:30 a.m. EST (1030 GMT)JOHNSON SPACE CENTER, Texas (CNN) -- Two spacewalking astronauts swapped science instruments on the Hubble Space Telescope early Friday, the most critical job of the observatory's billion-mile tuneup.
Astronaut Steven Smith, perched on the end of space shuttle Discovery's crane, removed a 7-foot-long box from Hubble containing a spectrograph that by coincidence failed just one week ago.
QuickTime Movie of spacewalk 28 sec./1M small movie
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Holliman Special InterviewWith partner Mark Lee guiding him, Smith gently slid in a more powerful instrument that will search for black holes and study newborn stars.
The next step for Lee and Smith was to replace one of Hubble's cameras with an advanced model that will peer into the infrared fringes of the universe.
Lee was surprised when the yellow-painted coating from shuttle handrails rubbed off on his pressurized gloves. "I wouldn't try to get some on you," he told Smith.
Special section: So eager were Lee and Smith to get started on their six- to seven-hour spacewalk out in the open cargo bay that they suited up two hours early Thursday night.
But their plans were foiled when a strange thing happened as they began to release air pressure from the airlock into the cargo bay. One of the two solar panels on the telescope began to turn wildly and had to be turned off by a computer command from Hubble's onboard computer.
Problem solved
Still inside Discovery, the astronauts used a hand-held spotlight to look around the solar panel for engineers and scientists on the ground.
When ground controllers first saw the telescope, they were amazed. The left side solar panel was in place, but the one on the right was tilted too close to the astronaut's work space.
There appeared to be no damage to either of the 40-foot, power-generating solar wings, and both appeared to be fairly steady, the astronauts said.
Engineers on the ground theorized that escaping air from the depressurization of the airlock moved the solar panel, like a sheet on a clothesline caught in a breeze. An alternative method was then used to slowly lower the airlock pressure and deflect the exhaust.
The plan worked, and after nearly two hours inside the cramped airlock, Lee and Smith went out nearly 370 miles above Earth to install two new science instruments that will allow Hubble to peer even deeper into the far reaches of the universe.
In the end, they were only 15 minutes behind schedule.
"Oh my gosh. Beautiful!" Lee said as he gazed upon the 12-ton, 43-foot tall observatory.
The first job on the outside for the astronauts was to set up the workspace, putting all the tools for the week into the cargo bay and stabilizing the telescope with a support bar to keep it from jiggling as the astronauts work.
Then it was on to the major mission of the night, opening two huge doors on the base of the telescope and removing the science instruments.
The first one out was the failed Goddard High Resolution Spectrograph, which took almost two hours to get in place.
In good shape
Twenty hours earlier, Discovery's seven-man crew hauled the telescope into the shuttle's cargo bay and latched it onto a tilt table.
"Seeing that beautiful spacecraft for the first time in three years was like seeing your best friend whom you haven't seen for three years," NASA's chief Hubble scientist, Ed Weiler, said on Earth. "Not only that, but the friend doesn't seem to have aged at all."
The only sign of age appeared to be a gouge in a dish antenna, caused by a micrometeorite. The healthy Hubble was a welcome sight; a badly warped or wobbly telescope would have forced NASA to call off the spacewalks.
Weiler considered the first spacewalk, on Thursday night, to be "the Super Bowl" of the series. The astronauts' job: to replace 1970s-era science instruments with state-of-the-art devices.
"If that goes well, I think it will really put Hubble into a position of having world-class scientific capability well into the 21st century," he said.
Scientists calculated that the capture of the telescope came on its orbit No. 37,130. The telescope had logged 996 million miles and made more than 110,100 observations of stars, galaxies, planets and other astronomical objects since its 1990 launch.
Although this rendezvous was less urgent than the 1993 visit, when spacewalking astronauts had to install corrective lenses because of a defective mirror, it was no less nerve-racking for astronomers, fearful of an inadvertent bump that could ruin its vision again.
The $2 billion telescope has performed superbly since its full sight was restored, confirming the existence of super-massive black holes in several galaxies and bringing astronomers ever closer in determining the age of the universe.
Its vision will be even keener with the addition of the two $100 million-plus science instruments, a spectrograph with two-dimensional sensors and a near-infrared camera. Each is the size of a telephone booth.
Other high-priority items to be hooked up before the telescope is turned loose next week: a refurbished guidance sensor and two data recorders. Altogether, 11 major parts are to be installed.
Correspondent John Holliman and the Associated Press contributed to this report.
Special sections:
CNN Interactive's extended coverageRelated stories:
- Delayed Hubble spacewalk begins - February 14, 1997
- 'It's a beautiful sight' - February 13, 1997
- Shuttle Discovery blasts off on Hubble service mission - February 11, 1997
- Anxious NASA officials watch high readings on shuttle - February 10, 1997
- NASA looks for oxygen leak; shuttle liftoff still on schedul - February 9, 1997
Related sites:
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- Hubble Space Telescope Science
- Johnson Space Center Shuttle Countdown STS-82
- Space Station Mir Info Page
- Tracking the mission
- Meet the Crew
- Watch the crew - NASA TV
- Watch the crew - streaming video
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