Spacecraft disasters continue to haunt NASA, cloud future

Since the first accident 39 years ago, critics doubt program's value, direction, saying it hasn't recovered.

by John Noble Wilford / New York Times

Anniversaries of the three most somber milestones in the American program of human spaceflight are clustered in the days ahead. Each in its own tragic way represents a pivotal moment in space exploration. The two most recent disasters continue to haunt the program with lost momentum and persistent doubts about its value and future direction.