The five astronauts scheduled to fly a classified military space shuttle mission late this month arrived here Saturday for training and a countdown test.

"It's going to be a busy couple days," commander Robert Gibson told reporters after he and his fellow crewmen flew in from their training base in Houston.Asked if NASA had set a launch date for the secret mission aboard the shuttle Atlantis, Gibson replied: "We're still marching toward the 28th, but there's a possibility of a couple days the other side of that."

Actually, those "couple days" already have been added, with the range schedule now listing the launch date as Nov. 30. Shuttle managers will set a firm date Wednesday following a two-day flight readiness review.

Gibson said his crew is "very excited" about the flight, much of which is cloaked in secrecy because of its military nature.

Sources have reported the astronauts will deploy a huge Defense Department intelligence-gathering satellite that will fly over 80 percent of the Soviet Union.

The exact launch time and length of the mission are classified. After Atlantis reaches orbit, there will be a blackout on information until the end of the flight.

Following the astronauts' arrival, Gibson and pilot Guy Gardner scheduled practice landing approaches on a runway here in a jet plane equipped to handle like a shuttle. The three mission specialists, Mike Mullane, Jerry Ross and William Shepherd, planned to rehearse driving a tank-like vehicle the astronauts would use in case they had to make an emergency escape from a launch pad problem.