The first woman and the first black astronauts to be selected for space flight were chosen yesterday by the National Aeronautics and Space Administration to be crew members on the seventh and eighth flights of the space shuttle in April and July, 1983.

Named to the four-member crew of the seventh shuttle flight next April was Sally K. Ride, 30, who has a doctorate in astrophysics from Stanford University and has been in astronaut training since 1978.

Named to the four-man crew of the eighth shuttle flight next July was Guion S. Bluford Jr., 39, a veteran of air combat in Vietnam who came to the Johnson Space Center in Houston in the eighth astronaut class there. It also included Ride.

Since Alan Shepard made America's first orbital space flight in 1961, all 44 U.S. astronauts who have flown in space have been white men, as will be all 10 crew members of the next three shuttle flights.

The choice of Ride to be the first U.S. woman in space came as no surprise. An expert on the mechanical arm that will be used on the shuttle to deploy satellites in space, Ride is the first woman to serve as a "capcom" in Houston's Mission Control Center, as she did on the second and third flights of the space shuttle Columbia.

In space jargon, a "capcom" (capsule communicator) is the astronaut on the ground who talks by radio to astronauts in space.

Ride was chosen at least in part because the seventh shuttle flight will be the only one of the next four flights on which the 50-foot-long arm will be used. Ride will use the arm to deploy a West German-built satellite to take measurements in space before being brought back aboard the shuttle.

A rugby and tennis player, Ride is one of the few astronauts who has not longed to be an astronaut since adolescence. Raised in the Los Angeles suburb of Encino, Ride was a doctoral candidate in astrophysics when she saw an advertisement in the Stanford campus newspaper that said NASA was seeking astronaut applications from women for the first time.

"A light flashed inside my head," Ride said recently. "As soon as I saw the ad, I knew that's what I wanted to do."

The choice of Bluford for space flight also is not surprising. A native of Philadelphia who went through engineering school at Penn State, Bluford flew more than 60 combat missions in Vietnam as an Air Force fighter pilot. One of three blacks chosen for the 35-member eighth astronaut class, Bluford has long been looked on as a leading candidate for early shuttle flight.

His flight will deploy in orbit the second of several satellites to be left in space as radio relays for U.S. satellites around the world. This series of radio links is planned to replace all of the large radio antennas that are scattered around the earth and whose links with manned and unmanned satellites can be interfered with by storms on earth.

Bluford has indicated that he feels a special pressure about being the first black astronaut in space. "It may be better to be second or third because then you can enjoy the experience a little more," he said in a recent interview. "It isn't something I'm running after."