Fuel glitch delays launch of Mars orbiter

NASA delayed the launch of a new Mars orbiter for a second time on Thursday because of rocket problems.

The Mars Reconnaissance Orbiter is designed to study the history of water on the planet. Scientists will use the information to plan where to land future landers and rovers.

Minutes before the planned liftoff on Thursday, the launch was delayed until Friday. The delay was caused by a faulty fuel sensor and software problems on the launch rocket.

NASA couldn't explain why the fuel sensor still read "dry" after the rocket was filling with propellant.

A fuel sensor problem also caused the space agency to delay the launch of space shuttle Discovery in July.

Wednesday's scheduled liftoff was scrubbed after navigational controls failed on a similar launch vehicle.

The Mars Reconnaissance Orbiter includes the largest-diameter telescopic cameras flown on a planetary mission. It is to survey Mars for large rocks that could pose a hazard on future missions.

Scientists will use the ground-penetrating radar on the orbiter to look for reserves of liquid water beneath the surface of Mars.

The orbiter's instruments will also zoom in on the surface of the planet, analyse minerals linked to water, trace atmospheric dust and monitor the weather.

Three other orbiters are already looking for signs of water and ice on Mars.