Everything Works on Shuttle’s Bonus Day : Craft to Land This Afternoon After ‘Superbly Successful Mission’

The space shuttle Challenger wrapped up a “dazzling” bonus day of sun gazing Monday and prepared to return home today.

“It’s the greatest pleasure to wind up with a dazzling day like this, with all the instruments working so well,” said astronaut Loren W. Acton, a solar physicist who spent eight years training for the spaceflight.

It was one of the few times during the eight-day mission that all of the instruments in Challenger’s powerful array of solar and stellar experiments worked at once.

“It’s more fun than a barrel of monkeys up here,” astronaut Karl Henize said.

Scheduled to Land Today

The shuttle is scheduled to land at 12:45 p.m. today at Edwards Air Force Base in the Mojave Desert after logging nearly 3.3 million miles in eight days of travel around Earth.

Flight director Al Pennington said that winds are expected to be gusting at up to 16 m.p.h. at the landing site, which is well within acceptable limits.

Chief scientist Eugene Urban said that important research was conducted in each of the flight’s 13 experiments and, in all, about 80% to 85% of the objectives were achieved. He called it a “superbly successful mission.”

Spectacular Observations

“Everyone has collected tantalizing new data,” Urban said in his final report before the landing. “It’s going to take a long time before this data is analyzed and really fully appreciated. We’ve made some interesting new observations and some of them have been very spectacular.”

The crew, Gordon Fullerton, Roy D. Bridges Jr., F. Story Musgrave, Anthony England, John-David Bartoe, Acton and Henize, prepared for the high-speed descent back into the atmosphere by checking flight controls and beginning to secure instruments in the cargo bay.

One potential problem cropped up Monday. Mission control spokesman Steven Nesbitt said the crew was told that there was a possible leak of hydrazine fuel in one of three hydraulic system turbines used to drive flight controls for the descent. The unit will be started late to minimize possible problems.

“The way it was phrased to the crew was a low-probability concern,” Nesbitt said. Flight director Pennington said later that no difficulty was expected.

Mission Was Extended

The landing originally was scheduled for Monday, but the mission was extended a day to give scientists more time to study the sun using a $60-million telescope pointer that earlier had aiming trouble. The sudden recovery of a fourth solar telescope Sunday added to the science bonanza.

Dr. Guenter Brueckner, a Naval Research Laboratory scientist in charge of two of the solar telescopes aboard the orbiting observatory, thanked the crew for a “tremendous finish.”

When Challenger lost power in one of its three main engines on the climb to orbit a week ago, scientists on the ground expressed considerable concern about being able to meet the mission’s objectives. The ship went into an orbit about 46 miles lower than planned, and 21% of its maneuvering fuel burned up.