Crew Photographs Lightning Storms : Atlantis Astronauts Replace Faulty Computer

On their final full day in orbit, the five Atlantis astronauts encountered their first problem when one of the orbiter’s four general-purpose computers “froze” and had to be replaced with a spare. Earlier Sunday, however, they finally got a chance to photograph some lightning before preparing for their landing at 12:43 p.m. today at Edwards Air Force Base, Calif.

The computer that failed did not control any flight-critical processes but directed the attitude of antennas and played a role in the on-board science experiments. Within 30 minutes after the failure was discovered, those functions were shifted over to the other three computers, and mission specialist Mark C. Lee began replacing it.

The process, which involved removing a row of lockers on the shuttle mid-deck to gain access to the computers, took about 3 1/2 hours. Another 1 1/2 hours were required to check the computer out after it was installed. An on-board computer has never been replaced in previous shuttle missions, but the astronauts have practiced it.

Poses No Threat

The failure of the computer posed no threat to the astronauts, or to the shuttle. Commander David M. Walker and pilot Ronald J. Grabe can land using only one computer. But it was replaced because NASA officials prefer to have all four computers functioning during re-entry.

Despite the slow pace of their orbital experiments before the computer failure, Walker said in a morning news conference that the crew had “really not relaxed. We’ve worked very hard.” Lee noted, however, that the workload was “not overwhelming for a five-man crew.”

The Magellan spacecraft, launched from Atlantis Thursday night, continued on its near-perfect voyage to Venus Sunday, while mission specialist Mary L. Cleave photographed some of the places visited by the 16th-Century Portuguese navigator Ferdinand Magellan during his trip around the world.

‘Got Some Good Pictures’

To laughter from the rest of the crew, Cleave said, “We got some good pictures of the Philippines,” where Magellan died before the voyage was completed.

When asked about the success of the mission, Walker replied that “I’d give it a 10 on my personal scale. . . . You couldn’t ask for a better flying machine than this one.”

Cleave, who has been studying the growth of crystals for the electronics industry in the near-weightlessness of microgravity, also noted that, “We’re hoping to bring back some great indium crystals.”

Check On-Board Systems

Walker and Grabe spent part of the day making certain that all on-board systems needed for today’s landing were in good working order.

But the highlight of the day came when the astronauts finally got the chance to photograph some lightning storms with the payload bay camera, as well as with a Sony camcorder that the crew has been testing. Atlantis had not passed over any large storms on the preceding two days.

‘Sympathetic’ Lightning

Sunday some expected storms over Australia did not materialize, but crew members observed lightning over Africa. Mission specialist Norman E. Thagard noted that he had observed some “sympathetic” lightning that began in the top of one cloud and triggered flashes in a succession of nearby clouds.

The astronauts are collecting data that will eventually be used in the design of lightning detection satellites that will be used to increase the accuracy of storm forecasts.

Researchers want to learn about lightning “to be able to give data out for . . . hazard identification, storm tracking,” said meteorologist Mark Christian of the Marshall Space Flight Center in Huntsville, Ala.

“We could tell where a storm is in its evolution, if it’s intensifying, whether it’s starting to die, what direction it’s tracking to,” Christian said. “It certainly should have impact in improved weather forecasts.”

Would Aid Industry

Lightning forecasts would be very useful to the airline industry and groups working outdoors, including construction crews, oil derrick workers and operators of large cranes.

With the Atlantis flight winding down, NASA officials are beginning to look ahead to future missions. The next shuttle mission will be the first post-Challenger flight of Columbia, tentatively scheduled for the beginning of August. It will carry a classified Department of Defense payload.

On Aug. 24, Voyager 2, launched in 1977, will fly by Neptune, sending back the first pictures of that planet. In the early parts of its 12-year trip, Voyager 2 has already returned pictures of Venus, Jupiter and Saturn.

On Oct. 12, Atlantis will return to space carrying the Galileo probe, which will reach Jupiter in 1995.

In November, Columbia will carry a communications satellite into orbit, while the piece de resistance comes in November, when Discovery will launch the Hubble Space Telescope, an event originally scheduled for early 1986.

“This is intended to be the year of the planets,” said Lennard Fisk, NASA’s associate administrator for space sciences.