On July 7 and with 3000 m showing on the odometer, Spirit's right front wheel motor began to show signs of jamming by the way of above nominal (150%) power consumption. Raising its leg and spinning freely to heat up the grease did not yield but a marginal improvement, so engineers went back to the drawing board to try figure out a way to keep going.
And they came out with a new rulebook for driving Spirit, namely turn around, drive backwards and think this is a six man raft with the back left one dipping the oar stuck. To do this they must also trick the rover to think it is steering straight yet a smuggled command veers the train sideways.
Sure this is easier said than done, more so when you have a single daily chance to upload trip commands and do not really know what the terrain has in store, at least in good detail. A spare rover here on Earth and in a good environmental replica, is regularly tasked with full dress rehearsal, that is, command sequence upload and then simply watch how it fares by itself.
No one to blame either, the wheel's gearbox has worked over 6 times the guarantee mileage and simply choose to quit while all others are doing fine. Team thinks the new rules can make do for a few more hundred meters, probably more if the failing leg is spared but for the absolutely unavoidable maneuvers.
RAT jam
Opportunity had its share of troubles, though in this case with a happy outcome. After grinding an rock by the name of Axel Heiberg (not the foggiest idea how it was christened) about Aug 16, everything pointed to a loose bit lodged between two of the grinding wheels.
Fortunately photographs taken with the close up camera on Aug 27 showed no traces of foreign material and the drill is now working as expected.
Though current circumstances are less than favorable, both rovers are gathering and sending information at a fast pace. This sums to about 150 Megabytes daily each, even considering Mars is rather poorly located in the sky by this time of the year.
By the way, it is winter now there, and feeble sunlight as available at the Mars distance is poorest yet, something that mandates extreme caution managing the power budget lest all contact be hopelessly lost. Most of the time rovers are put in a deep hibernation mode whereby all nonessential items are turned off.
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