Flight controllers were worried yesterday about their inability to have intelligible communication with the Mars rover Spirit since early Wednesday, an ominous radio silence that engineers could not explain but that they feared was caused by a software or hardware failure. With each passing hour and no clear message, concern grew that the mission of the robotic spacecraft might have come to an abrupt end, just as it was getting started ... "We have had a very serious anomaly on the vehicle." ... They may not know yet what its problem is, or if it is correctable, but they said they were sure that the rover was still alive. Tonight will be another long (Martian) day for our friends at JPL. A press release at the official web site adds, on a hopeful note, that Spirit did successfully respond, via Global Surveyor, to a 'ping' sent from Earth. However, engineers have still not determined why Spirit is seemingly unable to transmit mission data to Earth. Mars Rover Falls Silent, Fraying Nerves at NASA | 
