Article Posted on : - Mar 20, 2011

An artist's concept portrays a NASA Mars Exploration Rover on the surface of Mars. Photo by NASA/JPL/Cornell University

PASADENA, CALIFORNIA (BNS): Hopes for reviving NASA's Spirit Mars rover dimmed further with passage last week of the point at which the rover's locale received its maximum sunshine for the Martian year.

The rover team has tried to contact Spirit for months with strategies based on the possibility that increasing energy availability might wake the rover from hibernation, NASA said.

The team has now switched to communication strategies designed to address more than one problem on the rover. If no signal is heard from Spirit in the next month or two, the team at NASA's Jet Propulsion Laboratory, will shift to single-rover operations, continuing to operate Spirit's active twin, Opportunity.

"The commands we are sending starting this week should work in a multiple-fault scenario where Spirit's main transmitter is no longer working and the mission clock has lost track of time or drifted significantly," said JPL's John Callas, project manager for Spirit and Opportunity.

Spirit landed on Mars January 4, 2004, for a mission designed to last for three months. After accomplishing its prime-mission goals, Spirit worked for more than five years in bonus-time extended missions.

NASA's Deep Space Network of antennas in California, Spain and Australia has been listening for Spirit daily. The rover team has also sent commands to elicit a response from the rover even if the rover has lost track of time, or if its receiver has degraded in frequency response.

The available solar energy at Spirit's site was estimated to peak on March 10. Revised commanding began March 15, including instructions for the rover to be receptive over UHF relay to hailing from the Mars orbiters for extended periods of time and to use a backup transmitter on the rover.

Spirit and Opportunity both have made important discoveries about wet environments on ancient Mars that may have been favourable for supporting microbial life. Opportunity landed three weeks after Spirit.