Two successful data communications with the rover Spirit on Friday morning have given engineers hope of remedying a “serious anomaly”.
After nearly three weeks of successful operation on the surface of Mars, the rover experienced a problem on Wednesday and had failed to send any new data back to Earth since then.
But project manager Pete Theisinger reported two successful data transmissions from Spirit on Friday morning. The first took place at 1234 GMT at a rate of 10 bits per second and lasted for 10 minutes. The second occured at 1326 GMT, at 120 bits per second, and lasted 20 minutes.
Both were received by the Deep Space Network antenna near Madrid. This was the first real data received from the craft, other than simple continuous signals, since the problem began on Wednesday. It gives the team great reassurance that the problem can be understood and corrected. “The spacecraft sent limited data in a proper response to a ground command, and we’re planning for commanding further communication sessions later today,” Theisinger said.
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The rover has already returned spectacular images of the Martian surface, following a near perfect touch down on 3 January.
Unknown bug
The mission engineers are perplexed because its behaviour does not seem to match any known pattern of failure, and there was no particular activity or set of conditions at the time the problems began that seem to explain what has happened. They have been actively investigating several scenarios, including the possibility of some kind of overload, such as a sudden increase in heat or voltage, or some previously undetected bug in its onboard software.
If the problem turns out to be a software bug or a mechanical problem, then that might also affect its twin, Opportunity, which is due to land on the opposite side of Mars at 0505 GMT on Sunday morning.
Safe mode
On Thursday, an antenna of the Deep Space Network attempted to reach Spirit on a special frequency set aside for the rover to use if it had experienced a problem and had reset itself into a protective “safe mode.” Sure enough, the rover sent a tone on that frequency, indicating that it had determined through its own diagnostic capabilities that it had a problem of some kind. But the fact that it replied showed it was still capable of receiving, interpreting and responding appropriately to radio commands.
The rover’s initial communication failure began while the Deep Space Network antenna in Canberra, Australia, was attempting to send up instructions for the next day’s activities.
The team plans to continue attempting to elicit responses from Spirit that might help diagnose, and eventually fix, its problem. But by Saturday, the team’s attention will shift over to Opportunity, and if communications are not re-established by then, further attempts may have to wait until after a planned three-day stand-down, so that the team could give their undivided attention to Opportunity during its critical deployment on Meridiani Planum, near the Martian equator.
