Spirit May Never Phone Home Again

July 30, 2010:  NASA mission controllers have not heard from Mars rover Spirit since March 22 as the rover faces its toughest challenge yet - trying to survive the harsh Martian winter. 

On July 26, mission managers began using a paging technique called "sweep and beep" in an effort to communicate with Spirit... 

(Read the rest of http://science.nasa.gov/science-news/science-at-nasa/2010/30jul_spirit2/)