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.