Pete Theisinger, project manager for the Mars Rover mission uses a model of the NASA Mars Spirit Rover while briefing reporters the its status January 23.

    PASADENA, the United States, Jan. 23 (Xinhuanet) - US Mars rover re-established communication with Earth for 20 minutes on Friday, but scientists are still trying to find what had happened on the spacecraft, NASA said.

    "The spacecraft sent limited data in a proper response to a ground command, and we're planning for commanding further communication sessions later today," said Mars Exploration Rover Project Manager Pete Theisinger at NASA's Jet Propulsion Laboratory (JPL in Pasadena, California.

    Since Wednesday, its 19th day on Mars, the rover lost contact with Earth, sending back only meaningless radio noise or simple beeps acknowledging receipt of commands.

    JPL said the flight team for Spirit sent a command to the roverat 5:02 a.m., Friday, via the NASA Deep Space Network antenna complex near Madrid, Spain, telling it to begin transmitting. They received data at a slow rate of 120 bits per second in a 20-minutecommunication session that began at 5:26 a.m.

    Dave Hurst with JPL's newsroom said NASA scientists still did not know what had happened on the rover and were working to establish communication with the spacecraft at higher data transmitting rate.

    On Thursday, NASA said the flight team had telemetry problems in communicating with Spirit. At first, the problems were believedto be related to a thunderstorm over Australia. But later NASA said the problems apparently were more serious and could representa software or hardware failure. Enditem