Cassini to switch to backup thrusters

Pasadena, Calif. -- The U.S. space agency says it will switch the Cassini spacecraft to a backup set of thrusters due to degradation of performance in the main set of thrusters.

The thrusters are used for making small course and angular corrections, as well as some attitude control functions. The current set of eight thrusters, referred to as branch A, has been in use since Cassini's launch more than 11 years ago. The redundant set, branch B, is an identical set of eight thrusters.

An extensive review of the problem last week ended with a recommendation to swap to side B as soon as possible. The National Aeronautics and Space Administration said mid-March is the earliest practical opportunity to make the swap.

Although nearly all Cassini engineering subsystems have redundant backup capability, NASA said this is only the second time in Cassini's 11 years of flight that a backup system has been needed.

The Cassini-Huygens mission is a cooperative project of NASA and the European and Italian space agencies. NASA's Jet Propulsion Laboratory in Pasadena, Calif., manages the Cassini mission.

Copyright 2009 by United Press International.