Gliding somewhere through space, the all-military crew of the space shuttle Discovery spent this second day on the nation's first secret shuttle mission as publicly silent as they did their first.

Not a word was heard spoken between the ground and the crew, Navy Capt. Thomas K. Mattingly, Air Force Lt. Col. Loren J. Shriver, Marine Lt. Col. James F. Buchli, Air Force Maj. Ellison S. Onizuka and Air Force Maj. Gary E. Payton. The crew was launched into orbit aboard Discovery at 2:50 p.m. EST on Thursday.

At 7 a.m. EST today, the astronauts reportedly launched a $300 million spy satellite designed to eavesdrop on Soviet military and diplomatic communications. But there was no official confirmation.

The only communication this afternoon to the press "covering" the classified Air Force flight was a 15-word communique released from Houston's Johnson Space Center, which read:

"The orbiter Discovery, her crew and elements of the Space Transportation System are performing satisfactorily."

The Air Force has ordered that no ground-to-air communications be made public and that no briefings be given on the progress of Discovery's secret flight. The only information authorized by the Air Force are three daily "status reports" on the mission.

So far, three of these dispatches have been released.