Barring last-minute technical problems or bad weather, NASA's ambitious mission to service the Hubble Space Telescope and repair its flawed vision is scheduled to lift off before dawn tomorrow, agency officials said yesterday.
The mission -- which will stretch over 11 days and include five spacewalks, the most ever attempted -- hopes to improve and fortify the $1.6 billion telescope and restore NASA's reputation, tarnished by the discovery two months after the April 1990 launch of Hubble that its primary mirror was the wrong shape. Efforts to right that wrong began almost immediately with the expectation that astronauts could install corrective optics on the telescope during the project's planned 1993 servicing mission.
"I think the whole team recognizes the importance of this mission . . . both for the HST [Hubble Space Telescope] guys, astronomers throughout the world and NASA itself," said Mike Leinbach, the shuttle test director at the Kennedy Space Center.
The shuttle Endeavour, which will carry the seven-member crew to the telescope orbiting 377 miles above Earth, is scheduled to lift off from Kennedy Space Center in Florida at 4:57 a.m. tomorrow. Weather forecasters at Kennedy said late yesterday there was a 70 percent chance that strong crosswinds and low clouds would delay the flight until Thursday.
Air Force Capt. Dean Hazen, a weather forecaster at Kennedy, predicted better weather on Thursday and Friday.
With the cargo of sophisticated and costly instruments secured inside Endeavour, Kennedy Space Center crews began fueling the shuttle yesterday. The astronauts -- among the most experienced of NASA's spacewalkers -- settled into their eight-hour sleep cycles. To rendezvous with Hubble on time, the launch must take place before dawn, and astronauts must then sleep in the daytime and work at night.
Mr. Leinbach, the shuttle test director, said his crew had no outstanding problems that needed attention.
During a series of briefings yesterday, NASA officials, Hubble project managers and telescope scientists gave hearty and upbeat assessments of the potential success of the project, the most ambitious mission in the shuttle program's 12-year history.
"We're all confident that we are going to be successful," said Randy Brinkley, the mission director. "We go into this highly trained, highly experienced and very optimistic."
If the crew is unable to repair the telescope in orbit, it could threaten congressional support for the proposed manned space station, which would have to be built and maintained in orbit.
The success of the mission, as defined by NASA, depends on the number of tasks the crew accomplishes while in space. At a minimum, NASA hopes to correct Hubble's focusing problem for at least one of its astronomical instruments and replace at least one broken gyroscope.
A fully successful mission would ensure the telescope's reliability and longevity and the success of its 15-year science mission by replacing:
* Two solar panels, which now vibrate each time the spacecraft moves from sunlight to shadow, affecting its aim.
* Two failed gyroscopes to restore the redundancy of the telescope's aiming system.
* The Wide Field/Planetary Camera with an improved model containing a small mirror designed to cancel the flaw in the telescope's 94-inch primary mirror.
* The High Speed Photometer with COSTAR, a system of adjustable mirrors -- some no bigger than a dime -- designed to cancel the focusing flaw for three other instruments on board the space telescope.
* A malfunctioning magnetometer, which measures the telescope's position relative to the Earth's magnetic field.
* One of two electronics units that control the position of the solar panels, keeping them pointed at the sun.
By correcting Hubble's optical problems, NASA hopes to restore the full potential of the telescope's scientific capabilities.
The telescope was designed to enable astronomers to search for planets orbiting other stars, verify the existence of so-called "black holes" at the center of distant galaxies, study the evolution of galaxies and measure the age of the universe.
Scientists say they have made progress toward all those objectives, even with the telescope's limited ability to see faint objects and to study objects on crowded parts of the sky. But if the upcoming mission is successful, they hope to extend Hubble's vision to the farthest reaches of the universe, to see objects 10 to 15 times fainter than those visible now.
"The Hubble Space Telescope is one of our primary assets in the space science program," said Wes Huntress, associate NASA administrator. "It is our window into the deep universe."
Despite their confidence, NASA officials acknowledged that things may go wrong.
"I'm confident, but I'm concerned," said Ed Weiler, chief Hubble scientist at NASA headquarters. "What worries me is the fact that this is not a trip to Grandma's to fix the faucet. So many things can go wrong."