Shuttle Crew Prepares for Landing Today as Mystery Arises Over Satellite’s Orbit : Space: Touchdown of Atlantis is moved up because of the risk of high winds. Secret payload’s hide-and-seek behavior puzzles amateur trackers.

The Atlantis astronauts packed Sunday for a blustery California touchdown today as satellite trackers struggled to explain the mysterious hide-and-seek behavior of the ship’s secret payload.

The satellite’s presumably successful deployment Friday accomplished the major goal of the 37th shuttle mission, clearing the way for Atlantis and its five-man crew to land today on runway 15 at Edwards Air Force Base, Calif.

NASA officials announced Sunday that Atlantis was scheduled to touch down at 1:48 p.m. PST, about two hours earlier than originally planned, sources said, because of concern about high winds at Edwards.

“The landing period was altered slightly to optimize weather and lighting conditions,” the National Aeronautics and Space Administration said in a statement.

While Atlantis’ military mission is being conducted under a veil of secrecy, amateur satellite watchers spotted the shuttle’s payload flying about 125 miles ahead of the spaceplane Friday evening, indicating the satellite was launched earlier that day.

The satellite appeared as a bright, reddish “star” sailing through space just ahead of the shuttle, which was as bright or brighter than brilliant Jupiter.

When Atlantis flew over Cape Canaveral, Fla., Saturday and Sunday evening, the shuttle was alone. But as it entered Earth’s shadow on both occasions and began fading from view, it changed from brilliant white to ruby red, making it look similar to the satellite on Friday.

“I think what they were seeing is the shuttle plus something and that something is the big question,” said Ted Molczan, a respected Canadian satellite tracker. “Was it an optical illusion? Was it something in the cargo bay like the (cradle) for the satellite?

“The other one that is kind of tantalizing . . . is the possibility that they rendezvoused with what they deployed on Friday, so maybe we were seeing both objects. It’s hard to square everything otherwise.”

Sean Sullivan, a satellite tracker who routinely follows shuttle missions at the Kennedy Space Center, said the color of the shuttle as it faded from view indicated the astronauts may have been flying in close formation with the satellite.

“It was ruby red,” he said. “This was not your normal shuttle pass. I can’t think of any reason the shuttle would be red. If this is the end of classified missions, we might as well do it with a bang. And this one is a bang.”

Atlantis and its five-man all-military crew blasted off Thursday from the Kennedy Space Center to kick off the seventh and last fully classified shuttle flight, a five-day mission conducted under a cloak of secrecy with all communications between the astronauts and mission control in Houston blacked out.

But the astronauts did break radio silence to send greetings to U.S. troops in the Persian Gulf.

“To the men and women of Desert Shield,” said Air Force Col. Richard Covey, the shuttle skipper. “Whenever we’ve passed close to Saudi Arabia, we could not help but think of our soldiers, sailors, airmen and Marines deployed there for Desert Shield.

“As the holiday season approaches, the multiservice crew of Atlantis wishes those brave warriors peace and a speedy return home. Our prayers are for them and their families.”

On board besides Covey, 44, are Navy Cmdr. Frank Culbertson, 41, the co-pilot; Marine Col. Robert Springer, 48; Air Force Lt. Col. Carl Meade, 40; and Army Maj. Charles Gemar, 35.

The astronauts presumably spent Sunday testing the shuttle’s re-entry systems and packing up for the long glide back to Earth.

Atlantis’ payload has been widely reported to be either a low-altitude photo-reconnaissance satellite or an electronic signals intelligence--or “sigint”--spy station capable of intercepting military communications from an orbit 22,300 miles above the Equator.

But Atlantis was launched into an orbit carrying it only 28.5 degrees to either side of the Equator, well south of Iraq, for example, and the Soviet Union. Why a photo-reconnaissance satellite would be launched into such an orbit is far from clear.

Compounding the mystery, sources said, was that Atlantis’ payload was not equipped with an “inertial upper stage” booster, which is required to push heavy “sigint” satellites to their high orbits.

Atlantis is not believed to be equipped with a mechanical arm that would allow the astronauts to retrieve a payload once it had been launched from the shuttle.

“What would cause them to go back to it? There are some nagging things that would tend to say maybe we didn’t see a re-rendezous, that maybe we saw something else,” Molczan said. “There are so many things about this that are strange.”

Whatever the satellite is, Atlantis’ crew began training to launch it in May, 1989. Any duty the spacecraft might ultimately see over the Persian Gulf, then, would appear to be coincidental.

Sullivan said the strange behavior of Atlantis’ payload raised a third possibility: that the shuttle was carrying a new type of satellite altogether, or one dedicated to “Star Wars” research.

A payload for the space defense system is scheduled for launch early next year in a declassified military shuttle mission.