Hubble due for a house call Telescope: Astronauts to replace equipment that has faltered or become seriously outdated.

February 10, 1997|By Frank D. Roylance | Frank D. Roylance,SUN STAFF nTC

Seven American astronauts are set to rocket back to the Hubble Space Telescope early tomorrow for NASA's second in-flight house call on the 7-year-old orbiting observatory.

In the first of four spacewalks totaling nearly 25 hours, two pairs of astro-handymen are to install new, more advanced cameras and spectrographs. Astronomers say the gear will extend man's view closer to the origins of the universe, and deeper into dust-shrouded galaxies and stellar nurseries.

When that's done, NASA has a lengthy list of chores for the astronauts. The repair teams will take turns replacing equipment that has faltered or grown seriously outdated since the space telescope was designed in the 1970s.

"We're increasing the productivity of Hubble, to keep [it] in the forefront of science," said Dr. John Campbell, associate director of the flight project directorate at the Goddard Space Flight Center in Greenbelt.

The excitement at NASA turned chief Hubble scientist Dr. Edward Weiler positively metaphoric: He compared astronomy before Hubble to a two-lane highway. The 1993 repairs, he said, put it on an interstate.

But the 1997 upgrade, he said, "gives us four-wheel drive. It will enable us to get off the interstates and into the forests and hills where there aren't any roads."

If the shuttle has enough fuel, the crew will also try to boost Hubble into a longer-lasting orbit five miles higher.

The 10-day, $795 million mission is scheduled to begin early tomorrow with a spectacular 3: 56 a.m. launch from the Kennedy Space Center in Florida. The veteran crew members are Navy Cmdr. Kenneth Bowersox (commander); Air Force Lt. Col. Scott "Doc" Horowitz (pilot); and mission specialists Gregory Harbaugh, Steven Smith, Joseph Tanner, Dr. Steven Hawley and Air Force Col. Mark Lee.

If all goes well, the crew will chase down and capture the space telescope just before 2 a.m. Thursday.

Each of the six-hour spacewalks is scheduled to begin at 11: 21 p.m. on Thursday, Friday, Saturday and Sunday. They will be televised live on NASA Select TV, which is available on some cable and satellite TV systems.

Discovery should return to the Kennedy Space Center in a tricky 2: 43 a.m. landing Feb. 21. This is the second of four planned trips to Hubble; the next follow in 1999 and 2002.

1993 repairs

In some respects, NASA has less on the line this time than in December 1993, when astronauts had to prove they could fix a 12-ton, bus-size satellite hurtling through space at 17,500 mph.

Taxpayers and astronomers were also watching in 1993 to see whether the repairs would correct the blurred vision that had made the $2 billion telescope a public embarrassment, and a scientific disappointment, after its launch in 1990.

They could, and they did.

Hubble's discoveries since the 1993 repairs have made headlines and dominated astronomical conferences worldwide. Its best pictures have captured the public imagination, turning up in books, on posters and T-shirts.

"Not only is Hubble delivering answers to long-standing questions, it is now beginning to shake some of our long-held beliefs," Weiler said.

It has challenged whole textbook chapters on the life cycles of stars. Hubble astronomers have found that the universe appears to be younger than the presumed ages of some of its oldest stars. That paradox has forced theoreticians to re-examine what they'd been taught about the pace of stellar aging and death.

But that's OK, Weiler said. "It's the things you don't expect that are the most fun."

Among the Hubble discoveries:

A spectacular view of star nurseries amid the towering pillars of dust and gas in the Eagle Nebula.

A "deep field" view of what seemed like a nearly empty speck of sky. Hubble found it filled with 1,500 young galaxies, some appearing as they did soon after the beginning of the universe. Their forms are helping scientists understand galactic birth and evolution.

Conclusive evidence that black holes -- objects so dense not even light can escape their gravity -- are common and may lie at the core of most galaxies.

Detection of dust disks in the Orion Nebula that suggest that planetary systems may be forming around many stars in our Milky Way.

Detailed views of a comet's collision with Jupiter; photographic records of weather on Mars; the first surface map of Pluto; and evidence for oxygen in the atmospheres of the Jovian moons Europa and Ganymede.

One-chance rendezvous

The astronauts will have just one chance to rendezvous with Hubble. Orbiting 368 miles up, Hubble is near the limits of the shuttle's range. Discovery will not have fuel to make a second attempt.

The first job for astronauts Lee and Smith will be to remove the telescope's Faint Object Spectrograph and the Goddard High Resolution Spectrograph, which have been on board since Hubble's launch in 1990.

The task is like sliding two 750-pound refrigerators out of a closet with quarter-inch clearances.

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