Sally Ride, the first American woman to fly in space, died on Monday at her home in San Diego. She was 61.

The cause was pancreatic cancer, her company, Sally Ride Science, announced on its Web site.

Dr. Ride, a physicist who was accepted into the space program in 1978 after she answered a newspaper ad for astronauts, flew on the shuttle Challenger on June 18, 1983, and on a second mission in 1984. At 32, she was also the youngest American in space.

She later became the only person to sit on both panels investigating the catastrophic shuttle accidents that killed all astronauts on board — the Challenger explosion in 1986 and the Columbia crash in 2003....