Rover Missions Renewed as Mars Emerges from Behind Sun Jet Propulsion Lab -- As NASA's Spirit and Opportunity resumed reliable contact with Earth, after a period when Mars passed nearly behind the sun, the space agency extended funding for an additional six months of rover operations, as long as they keep working.     Both rovers successfully completed their primary three-month missions on the surface of Mars in April and have already added about five months of bonus exploration during the first extension of their missions...