The crew of Atlantis rose early Saturday morning and deployed a secret military satellite, if informed speculation is correct.

NASA has made no announcement concerning the mission since it reported that the shuttle had settled safely into orbit and opened its payload bay doors after its launch from Kennedy Space Center Friday morning. The space agency has said it will release information only in the event of a life-threatening crisis.The Air Force has imposed an information blackout on the mission, but published reports, based on statements by independent analysts and unidentified informed sources, have said the payload is a powerful highly advanced low-altitude radar reconnaissance satellite named Lacrosse. Designed to monitor Soviet military activity, it was launched on a trajectory that would position it in orbit to cover about 80 percent of Soviet territories.

The $500 million satellite is large enough to have filled almost all of the shuttle's cargo bay, which is 60 feet long and 15 feet in diameter, according to Aviation Week & Space Technology Magazine. The trade magazine first published details of the mission last month.

The payload was to be lifted from the cargo bay and released into space by astronaut Richard Mul-lane, a mission specialist trained to operate the shuttle's remote manipulator arm.

After its release, two long arms attached to the core of the satellite were to unfold to a wingspan of as much as 150 feet. They carry solar panels to power the radar, plus censors and antennas that will collect and relay intelligence, experts say.

After releasing its cargo, Atlantis was expected to fly in formation with Lacrosse until the crew is satisfied that the satellite is functioning properly.

In case the payload had a problem, mission specialist William Shepherd and Jerry Ross are ready for a space walk. Ross is a veteran of two six-hour space walks in late 1985.

They might have been required to "nudge" the long arms into place during deployment, said John Pike, of the Federation of American Scientists. Or they might have had to blow the arms off to bring the package into the shuttle bay for repairs.

The only official information on the all-military crew's activities in orbit so far is their menu.

The shuttle will land at Edwards Air Force Base in California, possibly as early as Monday.