The space shuttle Discovery is scheduled to participate next month in the first "Star Wars" experiment in orbit, carrying a mirror intended to intercept and reflect a laser beam fired from Earth, the Pentagon's Strategic Defense Initiative (SDI) Office said yesterday.

In some concepts of a space-based missile defense system such as the proposed SDI, a large orbiting mirror would receive a powerful beam from a ground-based laser and bounce it in another direction to destroy a Soviet missile.

In the shuttle experiment the laser beam will be too weak to harm the spacecraft. A small mirror will reflect the beam back to the ground so engineers can verify their ability to keep the laser pointed at the orbiting mirror.

The laser will be aimed from an Air Force base on the Hawaiian island of Maui and bounced back by a special 8-inch-diameter "retro-reflector" that the astronauts will place in one of the shuttle's mid-deck side windows. While Discovery is over the Pacific, astronauts will keep the mirror-equipped window looking down.

Because the mirror is of a prismatic type that reflects light beams back to their sources, engineers on Maui will know whether the laser's aiming mechanisms can stay on target. On earlier tests, an SDI spokesman said, the laser had successfully tracked an airplane carrying the mirror at an altitude of 30,000 feet. The shuttle flies in orbit at 100 miles and more.

The use of ground-based lasers is one of several options that SDI engineers hope to evaluate over a period of years before deciding whether an antimissile system is feasible. Some concepts under study call for lasers to be kept in orbit, ready to fire directly at Soviet missiles and the warheads they release.

The Maui laser test, called the "high precision tracking experiment," is planned as the first in a series that the SDI has booked aboard shuttle flights. Beginning in 1987, two major SDI experiments will be flown each year.

In related developments:

* The National Oceanic and Atmospheric Administration said the $50 million NOAA-8 weather satellite that malfunctioned nearly a year ago has been restored to life and soon will be back in full service transmitting daily weather photos and information. Two months ago, its backup control system showed surprising signs of life and a team of NOAA, National Aeronautics and Space Administration and space industry engineers gradually revived it.

* Olympic medalist Kathy Johnson and five other world-class gymnasts performed acrobatic stunts usually prevented by Earth's gravity as a KC135 jet transport created 30 seconds of weightlessness by flying high arcs followed by steep dives. The Johnson Space Center in Houston said only one gymnast became ill. On an earlier flight, wearing blindfolds, all but one got sick. "Oh, God, it's great," Johnson said of the second flight. "It ranks right up there with the most exciting experiences I've ever had."