The space agency announced yesterday the selection of 15 new astronaut candidates -- the first since the Challenger disaster -- including the first black woman to enter the program.

She is Mae C. Jemison, 30, a medical doctor who is in general practice with Signa Healthplans of Los Angeles.

"Basically, I really consider it very important for the United States to continue its efforts in space," she said in a telephone interview between patient appointments. "It's something I've wanted to do all my life, and I thought I could contribute."

The explosion of the space shuttle Challenger in January 1986, in which all seven crew members were killed, she said, is "a risk I considered when I applied. I don't consider this current period {of problems} beyond redemption. I mean, there's always a lot that can go wrong" in such complex undertakings.

Jemison was born Oct. 17, 1956, in Decatur, Ala., received a bachelor of science degree in chemical engineering from Stanford University in 1977 and a medical degree from Cornell University in 1981.

Despite the shuttle's being grounded for at least 29 months after Challenger disaster, the National Aeronautics and Space Administration had a pool of 1,962 applications from which to select, officials said.

The chosen 15 include seven pilots and eight mission specialists. Five are civilians and 10 are military. There is one woman in addition to Jemison, bringing NASA's female astronaut contingent to 14.

In another "first," Lt. Cmdr. Bruce E. Melnick, 37, of Traverse City, Mich., is the first Coast Guard officer to be named an astronaut.

The 15 will report to Johnson Space Center in Houston in mid-August for a year of training and further evaluation before they begin training assignments leading to a slot on a shuttle crew.

The newcomers' first shuttle flight is probably at least four years away, according to spokesman Steven Nesbitt at Johnson Space Center.

Ten astronauts have left NASA since the shuttle accident. There currently are 82 in the corps, including some who have taken management jobs, such as Sally Ride, the country's first woman in space. Ride recently shook the agency by announcing that she will resign Aug. 15 to join a California arms-control think tank.

Before yesterday's announcement, NASA had selected at total of 157 astronauts in 11 groups since 1959, most recently in June 1985. The new class will bring the total strength of the corps to 96, still about 10 short of the pre-Challenger peak reached in the summer of 1985, Nesbitt said.

NASA may equal or excede that peak in the next few years, he said, as it begins to train astronauts not only for shuttle duty but for the proposed space station due on line in the mid-1990s.