Overview: Mars is the brightest thing in the sky and is at its closest to Earth for the next four years. With NASA announcing that its Martian rover Spirit is to rove no more on the red planet, there is an interview with Prof Steve Squyres, the principal investigator of the Mars Exploration Rover Mission, about the attempts to get it out of the sand dune which ensnared it in May 2009 and the agonising decision to stop the rescue.