Spacecraft Bound For Saturn Develops Problem

Spacecraft Bound For Saturn Develops Problem

PASADENA, Calif. (January 13, 1999 10:08 p.m. EST http://www.nandotimes.com) - The plutonium-powered Cassini spacecraft has detected a possible error in its orientation on the way to Saturn, NASA's Jet Propulsion Laboratory said Wednesday.

The operations team has remained in contact with the spacecraft, which sensed the possible problem on Monday and triggered a program designed to halt all non-critical activity and maintain a communications link with Earth until it can be corrected, a JPL statement said.

Cassini, NASA's biggest and most complex interplanetary probe, is on a $3.4 billion mission to explore the ringed planet. It was launched on Oct. 15 from Cape Canaveral, Fla., over the objections of anti-nuclear protesters who feared what might happen if the rocket exploded while carrying Cassini and its 72 pounds of extremely poisonous plutonium.

The spacecraft is on a roundabout trip through the solar system in which it will use gravity assists from planets to reach Saturn in July 2004.

The JPL statement said that at about 3 p.m. Monday, the spacecraft was in the midst of an instrument checkout exercise when it sensed a potential error.

The spacecraft launched what is called its "safe mode" program to begin using minimum power and pointing its 12-foot antenna toward the sun to shade the rest of the spacecraft.

Communication with the spacecraft was being conducted with a low-gain antenna.

Cassini Program Manager Bob Mitchell said engineering data from the spacecraft are being transmitted to Earth to help engineers pinpoint what caused Cassini to enter the safe mode.

Mitchell said he expects Cassini will be taken out of safe mode later this week after the problem has been identified and data thoroughly analyzed.