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Mars Rover Spirit Remains Quiet as Dust Storm Weak

Started by kmichaelm, 11/13/2008 10:32AM
Posted 11/13/2008 10:32AM Opening Post
Spirit is weathering a bad dust storm that has some worried... KMM

Press Releases November 12, 2008

Mars Rover Spirit Remains Quiet as Dust Storm Weakens

PASADENA, Calif. -- A dust storm that has reduced power to NASA's Mars Exploration Rover Spirit is clearing, but the Spirit's status remains unknown on Wednesday.

Mission controllers sent a set of commands to the rover early Tuesday, Nov. 11, telling it to follow several energy-saving steps, including not trying to communicate before Thursday. The team's immediate goal was to keep Spirit out of a pre-programmed protective mode that is triggered when battery charge is depleted below a safety level. The new commands, if received, would allow the team to keep more active control of Spirit than is possible when the rover is in the low-power protective mode.

"Like concerned parents, if we can stay in communication with the rover, we are in a better position to help," said John Callas of NASA's Jet Propulsion Laboratory, Pasadena, Calif., project manager for Spirit and its twin, Opportunity.

Controllers listened overnight Tuesday to Wednesday in case Spirit had entered the protective mode and attempted to communicate. It could be a favorable sign that Spirit was not heard from, because that could mean that the rover has received and is following the commands sent Tuesday. However, another possibility is that Spirit has not only entered the low-power protective mode, but that its battery power is so low it would not wake up to communicate.

"We likely won't know anything definitive until Thursday," Callas said. "The good news is that we have indications from Mars Reconnaissance Orbiter that the dust storm on Mars is clearing over Gusev." (Spirit is working in a range of hills inside Gusev Crater, which is about the size of Connecticut.)

Meanwhile, controllers will continue to listen for communication from Spirit at the times the rover would be expected to communicate if it has entered the low-power protective mode but still has enough power to transmit a signal.

Spirit has been operating on Mars for nearly five years in an exploration mission originally planned to last three months. A coating of dust on its solar panels is reducing its ability to generate electricity even when the sky is clear.

Press Releases November 10, 2008
Dust Storm Cuts Energy Supply of NASA Mars Rover Spirit

PASADENA, Calif. -- A dust storm on Mars has cut into the amount of sunlight reaching the solar array on NASA's Mars Exploration Rover Spirit, leaving the rover in a vulnerable state.

Spirit's solar array produced only 89 watt hours of energy during the rover's 1,725th Martian day, which ended on Nov. 9. This is the lowest output by either Spirit or its twin, Opportunity, in their nearly five years on Mars, and much less energy than Spirit needs each day. The charge level of Spirit's batteries is dropping so low, it risks triggering an automated response of the rover trying to protect itself.

"The best chance for survival for Spirit is for us to maintain sequence control of the rover, as opposed to it going into automated fault protection," said John Callas of NASA's Jet Propulsion Laboratory, Pasadena, Calif., project manager for Spirit and Opportunity.

Mission controllers are commanding Spirit to turn off some heaters, including one that protects a science instrument, the miniature thermal emission spectrometer, and take other measures to reduce energy consumption. The commands will tell Spirit not to try communicating again until Thursday. While pursuing that strategy the team also plans to listen to Spirit frequently during the next few days to detect signals the rover might send if it does go into a low-energy fault protection mode.

Mars weather forecasts suggest the dust storm may be clearing now or in the next few days. However, the dust falling from the sky onto Spirit's solar array panels also could leave a lingering reduction in the amount of electricity the rover can produce.