WASHINGTON -- A federal panel investigating the disappearance of NASA's Mars Observer space probe concluded yesterday that the spacecraft probably leaked enough fuel -- barely two tablespoons full -- to cause an explosion, knocking the first U.S. mission to Mars in 17 years out of contact with Earth.
But the panel noted that no one will ever know for certain exactly what happened to the Mars Observer. No sign of the probe has been detected since August.
Mission controllers plan one last attempt to contact the missing spacecraft next month, but they do not expect the probe to reply.
"The board, in fact, found no smoking gun," said Timothy Coffey, research director of the Naval Research Laboratory, who led the panel.
The panel of NASA-appointed experts, which has conducted an exhaustive review of the project since the spacecraft vanished Aug. 21, also cited evidence of sloppy workmanship and criticized management at the Jet Propulsion Laboratory in Pasadena, Calif., which had overall responsibility for the interplanetary probe.
The Mars Observer, the first U.S. interplanetary probe to fail in flight since 1967, was designed to provide the most detailed look yet at the fourth planet, serving as a pathfinder for an international fleet of probes to be launched toward Mars in the coming decades.
National Aeronautics and Space Administration officials at the Jet Propulsion Laboratory, who concurred with the board findings yesterday, had blamed the failure on a broken transistor in a small but crucial on-board clock.
Another group, called the Mission Success Review Team at Martin-Marietta Corp., which built the missing probe and two other satellites that failed last year, attributed the Observer's demise to an attitude: Overconfidence on the part of the engineers who built the probe.