Mars Trip Is Delayed a 2nd Time

CAPE CANAVERAL, Fla. -- Thunderstorms prompted NASA to postpone the launching of the first of its two Mars rovers Monday -- the second delay in two days.

The space agency will try again today with a launching scheduled for 10:58 a.m. PDT at the earliest. The weather outlook is “significantly improved,” said Kennedy Space Center spokesman George Diller. He said there was a 30% chance of weather canceling the launch today, down from 60% to 80% in recent days.

The $800-million twin Mars Exploration Rovers are set to reach Mars in January and begin a search for traces of water that may have persisted on the planet’s surface in the distant past.

The second rover is scheduled to launch on June 25 after midnight, when temperatures and the chance of thunderstorms are lower. The times of launching are set by determining the most efficient path for the spacecraft to reach Mars, said the mission’s manager, Pete Theisinger of the Jet Propulsion Laboratory in Pasadena, where the spacecraft were built.

If they survive their journey and rough air bag landing, the two rovers will roam across the Martian surface, analyzing and grinding open rocks to understand the planet’s past.

European Space Agency officials said that its Mars Express orbiter and Beagle lander, also speeding toward Mars, passed a navigation milestone and first critical test.

The spacecraft, which launched June 2, has traveled more than 620,000 miles so far. It released clamps that held the lander to the orbiter to keep it safe during the rough vibrations it encountered during its blastoff from Kazakhstan aboard a Russian Soyuz rocket.