The fourth American woman astronaut -- and the first U.S. astronaut mother -- is scheduled to go into orbit Wednesday on the second voyage of the space shuttle Discovery.

Dr. Anna Fisher, 35, will be part of a five-member crew. During her eight days in orbit, the physician will be the guardian of the first commercial chemical experiment to be flown in space, a still-secret container built by the Minnesota Mining and Manufacturing Co. to grow pure organic crystals in the weightless state. The company hopes to incorporate the crystals in the optical fibers now being used to link computers and telephones across the United States.

Fisher also will operate the shuttle's 50-foot-long mechanical arm to help astronauts Joseph P. Allen and Dale A. Gardner try to retrieve two "lost" communications satellites. The satellites -- Indonesia's Palapa B and Western Union's Westar VI -- were deployed during a space-shuttle mission last February but settled into useless orbits when their motors misfired.

Fisher and her husband, Bill, applied for the astronaut corps together but she was selected first. On their first Christmas at Houston's Johnson Space Center, Bill gave Anna a plaque that reads: "The best man for the job may be a woman." The two astronauts are parents of a daughter, Kristin Anne, born July 29, 1983. TNEXT STOP, MARS . . .

"Man's next destination in space is the resource-rich planet Mars," former NASA administrator Thomas O. Paine said last week, when he opened the NASA Symposium on Lunar Bases in the 21st Century at the National Academy of Sciences.

Along the way to Mars, Paine said, the United States will have to establish a permanent moon base "to leave behind selected materials, equipment and supplies, with qualified men and women remaining to work between regular supply trips."

Paine contends that there are no stumbling blocks to colonizing the moon or Mars. "The major problem is not technical but institutional," he said. "The great breakthrough that sent men to the lunar surface in 1969 was the 1958 invention of NASA. The annual budget cycle in Washington has never precluded long-term investments; a four-year term of office has never hampered presidents with vision."

If the United States doesn't do it, Paine said, the Soviet Union will. He looked ahead to 1995: "This decade opens with a triumphant Soviet expedition to Mars. Spectacular docking scenes at Phobos one of Mars' two moons show spacewalking by seven men and four women that dominate world TV. The president of the United States receives an electronic postcard from the cosmonauts reading: 'Having a wonderful time -- wish you were here.' "