Article Posted on : - Jan 29, 2009

Artist's concept of Mars rover Spirit on the Red Planet. NASA image

WASHINGTON (BNS): NASA’s Mars Exploration Rover Spirit did not report some of its activities this weekend, including a request to determine its orientation after an incomplete drive. The team operating Spirit has decided to carry out diagnostic tests this week.

NASA said that on Sunday, information radioed from Spirit indicated the rover had received its driving commands for the day but had not moved. “That can happen for many reasons, including the rover properly sensing that it is not ready to drive. However, other behaviour on Sol 1800 was even more unusual: Spirit apparently did not record the day’s main activities into the non-volatile memory, the part of its memory that persists even when power is off,” NASA said which has caused the alarm.

The space agency said that Spirit’s controllers at the Jet Propulsion Laboratory in Pasadena, chose to command the rover on Tuesday, Sol 1802, to find the sun with its camera in order to precisely determine its orientation. “Not knowing its orientation could have been one possible explanation for Spirit not doing its weekend drive. Early Tuesday, Spirit reported that it had followed the commands, and in fact had located the sun, but not in its expected location,” NASA said.

"We don't have a good explanation yet for the way Spirit has been acting for the past few days," said JPL's Sharon Laubach, chief of the team that writes and checks commands for the rovers. "Our next steps will be diagnostic activities."

“Among other possible causes, the team is considering a hypothesis of transitory effects from cosmic rays hitting electronics. However, on Tuesday, Spirit apparently used its non-volatile memory properly,” NASA said.

Project Manager John Callas of JPL said on Wednesday that despite the rover's unexplained behaviour, right now, Spirit was under normal sequence control, reporting good health and responsive to commands from the ground.