Mars Trip Is Bust

NASA has delayed this summer's launch date for the first of two Mars rovers after discovering they were vulnerable to short circuits that could have doomed them.

NASA must partially disassemble both rovers to fix the problem, delaying launch of the first from Cape Canaveral, Fla., by eight days, to no earlier than June 6. The second rover is expected to be launched between June 25 and July 15 as scheduled.

The robots have electrical connections to the spacecraft carrying them to Mars. Recent testing revealed a guillotine-like device designed to sever the cables could produce a short circuit that might affect circuit boards inside the rover, NASA said.

Project manager Peter Theisinger said such a short could cause the rovers to lose the radar data they require to determine their position and velocity during descent to the surface of Mars, expected in January 2004.

"That could be mission catastrophic," Theisinger said.

The discovery has prompted NASA to order an independent review of the rovers' design process to ensure there are no other such problems, Theisinger said. It was not immediately clear why the problem was not caught earlier.

NASA has stepped up testing and oversight of its Mars missions after it lost two spacecraft in 1999. The Climate Orbiter flew too close to the planet because of a mix-up between English and metric units, and the Polar Lander likely plunged to the surface when its descent rockets were prematurely shut down.

The pair of rovers were designed to operate as robotic field geologists in the hunt for evidence of past water activity on Mars. NASA announced Friday it is targeting the rover to land at two sites that scientific data suggest once abounded in water.