Challenger's last words.

Challenger's last words 

"Roger. 'Go' at 'throttle up.'" Those words from the space shuttle Challenger's commander, Francis R. Scobee, had been described by NASA as the last before the craft exploded during its jan. 28 launching. But careful analysis of an on-board tape that had been recording the crew's voices has revealed a single additional comment. Said Challenger's pilot, Michael J. Smith: "Uh-oh."

The last remark, says NASA, has provided "the first potential indication of [the crew's] awareness" that something was wrong. Less than half a second earlier, the craft had made a sudden movement to the right, possibly the result of the first stages of the explosion. And almost coincident with Smith's comment, a brilliant flash was seen between the shuttle and its external fuel tank.

The actual cause of the seven crew members' deaths, however, "cannot be positively determined," says former astronaut joseph P. Kerwin, now director of life sciences for NASA's Johnson Space Center in Houston. The forces of the orbiter's breaking up "were probably not sufficient to cause death or serious injury," says Kerwin, though the astronauts "possibly, but not certainly" lost consciousness due to loss of the cabin's atmospheric pressure. Alive or dead, however, they then hit the ocean at about 207 miles per hour, "far in excess" of "crew survivability levels."