Although many engineering experts consider the space shuttle's web of sensors and computers interacting with humans to be a data-processing masterpiece, the system apparently could not highlight quickly the one clue that pointed to disaster.
With photographs showing a leak in a solid rocket booster at least 14 seconds before the space shuttle Challenger exploded, serious design inadequacies in the elaborate warning system seem to have prevented space agency monitors from immediately detecting what was going wrong.
Just after the explosion, National Aeronautics and Space Administration officials at the Mission Control Center in Houston said there was "no anomalous data" on computer consoles that receive and display information on practically all of the shuttle's vital signs.
NASA spokesmen have indicated that data showing a problem in the burning booster may have been available but not displayed on computer screens watched by the shuttle commander and ground engineers tracking Challenger, or that the information was displayed but the computer program tracking the booster reported nothing unusual.
Published reports, not confirmed by NASA, indicate that the shuttle's telemetry -- its network of sensors and computer processors -- detected a 4 percent drop in the leaking booster's pressure.
When the booster began spraying a plume of flame, three sensors should have immediately detected the leak because of the loss of pressure. That data would have been immediately relayed to onboard shuttle computers and ground tracking stations.
According to NASA spokesman John Lawrence, data on solid-rocket-booster pressure is constantly displayed before the shuttle commander as a number sequence on one of the orbiter's four video display terminals.
Typically, this "PC" gauge shows a three-digit number counting down to 50, Lawrence said, at which point the boosters should be disengaging.
However, unless the onboard computers included a special "caution and warning system" program to alert the commander to a pressure drop, a change on the PC gauge could have been overlooked amid the welter of other displays.
It is also possible that a 4 percent drop in booster pressure would fall within margins of error permitted by NASA and Morton Thiokol, the booster's manufacturer, NASA spokesman Jim Mizell said. However, it is likely that the drop accelerated as the plume grew larger and that such a trend would register on ground consoles, he said.
On the ground, the "booster systems officer" is responsible for monitoring the boosters, Lawrence said. This person receives the PC gauge data displayed in the shuttle, as well as data about the hydraulic system that can be adjusted to steer the boosters in flight.
However, the officer also tracks the status of the main engines, which have proven to be the most troublesome component in the labyrinth of shuttle technology.
Mission Control consoles can display more than a dozen categories of telemetry information simultaneously, according to Lawrence, with instant access to hundreds more at a single keystroke.
"You have to be careful how many variables you choose to display at any one time," said Mizell, formerly an engineer on the Apollo moon program. "You don't want your reach to exceed your grasp."
However, unless the console is preprogrammed to alert the booster officer about a potentially harmful data change -- hitting a "red line," in NASA lingo -- it is possible that the pressure drop was not immediately noted.
If the 4 percent variance was not considered a "red line" condition, the data could be displayed on Mission Control screens without being considered "anomalous."
If the leak had been detected by Mission Control, Lawrence said, "the booster systems officer would call the flight director, who would call" the capsule communicator to alert the crew, taking less than 15 seconds.
However, most experts agree that the astronauts were powerless to save themselves.