More than a year after it first lost contact with its Mars rover Spirit, NASA has finally decided to throw in the towel. Yesterday, the agency confirmed that it will end all planned communications with the robot on May 25th, effectively ending the craft's seven-year mission. NASA was hoping that the approaching Martian spring would allow the Spirit to recharge its solar panels and re-establish radio contact, but it now appears that the craft sustained irreparable damage last winter, when it was forced to endure brutally cold temperatures. NASA executive David