Engineers from the NASA Jet Propulsion Laboratory confirmed last week that the Mars rover Spirit didn't communicate with the Mars Odyssey spacecraft as scheduled. Spirit, which is likely in power-saving hibernation mode, has endured yet another harsh time on Mars against all odds -- though it is believed the rover will wake up at some point.

Scientists gave the struggling rover communication schedules for 2010 and 2011, with expected communication with NASA officials on Earth and the Mars Odyssey.

"We are checking other less likely possibilities for the missed communication, but this probably means that Spirit tripped a low-power fault sometime between the last downlink on March 22 and yesterday," said John Callas, Mars rover project manager, in a statement.

Spirit faces an even bigger problem now that less sunlight is hitting its solar panels, which means the rover's battery power is dwindling.  There was previous concern when a strong dust storm hit the Red Planet, covering the rover and its solar panels.  The rover became stuck in early 2010 -- and remains stuck -- though researchers hope it will still be able to conduct research on a limited basis.

NASA officials will continue to wait to hear back from Spirit, but will have to wait until its battery is fully charged.  

Both Spirit and Opportunity launched from Earth around seven years ago, and finally made it to Mars in early 2004.  Each rover has explored the Martian surface in an effort to learn as much as possible about the Red Planet.