As the debris fell from the space shuttle Discovery during its launch yesterday, NASA faced its greatest nightmare: The prospect of a third catastrophic accident. Yet unlike the 1986 Challenger explosion and the 2003 Columbia breakup on reentry, this time NASA's decision-making processes--and the truth or falseness of its much-vaunted concern for astronaut safety--will be in full public view.

We know that the Challenger was lost precisely because NASA insisted on launching it despite the warnings of engineers that the frigid cold could lead to failure of O-ring sealers in the fuel tanks. Why? We know that too: because President Ronald Reagan was to give his state of the union speech that evening, and the Challenger--whose crew included the first teacher in space, Christa McAuliffe--presented a major propaganda opportunity. Whether or not the White House put direct pressure on NASA to launch despite the treacherously dangerous conditions is unimportant; NASA obviously felt under pressure to do so, and the astronauts' safety be damned.

The Columbia episode demonstrated a similar lack of concern for astronaut safety. Former astronaut Sally Ride, who served on both the Challenger and Columbia investigation boards, was quoted as saying "I'm hearing an echo here." Rightly so: NASA had known for many years that there were problems with damage to protective tiles, but decided--emphasis here on the word "decided"--to go ahead despite calculated risks to the astronauts. And there was no consideration of rescuing the astronauts, for example by asking the Russians to help out with their much more reliable Soyuz craft.

So here we go again. What decisions will NASA make? How much will they spend to insure the astronauts return safely? The world is watching much more closely this time.