Probe Ready for Mars Orbit

NASA's Mars Global Surveyor spacecraft is poised to enter the orbit of the Red Planet on Thursday, and officials at the Jet Propulsion Laboratory (JPL) in Pasadena, California, today said that the craft had completed the critical pressurization of its propulsion system without any problems. Four years ago, a similar mission to Mars, the Mars Observer, failed during this significant phase of the operation.

"With just hours to go before the Global Surveyor arrives at Mars, everything--and I mean absolutely everything--is in picture-perfect shape for the encounter tomorrow," says Glenn Cunningham, a project manager at NASA. Pressure in the fuel tank is at a safe level, and the spacecraft's trajectory "is right on the money," says Cunningham.

Allen Wood, a JPL spokesperson, recalls how scientists lost contact with the Mars Observer 4 years ago, just as it was getting ready for orbit. "Our guess is that there was a valve leak in the propulsion system lines," he says. "The fuel leaked during interplanetary flight, and it mixed with oxygen and oxidized during the pressurization of the system. During the maneuvers, we lost contact with it and never heard from it again."

If Global Surveyor safely enters orbit, it will train several instruments on Mars, including a magnetometer and laser altimeter, which will gather data for calculating the height of surface features on the planet. The Mars Orbiter Camera can spot martian rocks and other objects as small as 1.4 meters wide.