Spirit's still "extricating"
Posted by Emily Lakdawalla
2010/01/08 01:08 CST
I want to apologize for some confusion I created when I got confused earlier this week about the current status of the Mars Exploration Rover Spirit. Although Spirit's outlook remains gloomy and she's still buried in soil at Troy, JPL has not (as I said earlier) ended extrication efforts for the season in order to focus on winter survival. That decision may yet be made, but it hasn't yet; as of last night, rover driver Scott Maxwell told me, "extrication attempts are ongoing, at least for now."
It's been two months, now, that extrication efforts have been going on. It's discouraging that the rover isn't out of the trap. But I think I am actually more confused than I am discouraged. Mars -- and Spirit, ever the drama queen -- keep throwing curveballs at us on Earth. Almost none of the drives have proceeded to completion as commanded. Sometimes they abort for reasons that make perfect sense (like when Spirit was commanded to turn the wheels in place, but had to quit when the soil packed around one wheel proved too resistant to wheel motion). Most of the time, though, weird stuff happens: the right rear wheel up and died. The right front wheel moves -- sometimes. Weird readings indicate transient electrical problems. And so on. My head hurts trying to think about all the different variables they're dealing with.
I put together an animation of the right front hazcam images that ended each day of work, from sol 2078 to sol 2138, and annotated them with information from the JPL website. The very last frame seems to show Spirit rising out of the ground by a pretty significant amount, as measured by how much Husband Hill moves -- but that could just be tilt, purchased at a cost of Spirit's back end sinking, and moreover that tilt is in the wrong direction for winter survival. So it could be good news or it could be bad news.
Spirit, cut the drama already!
Here's a summary of what's happened to date. RR = right rear wheel; RF = right front; LM = left middle; etc. Sol 2088: Drive forward, aborted due to too-tight limit on rover tilt Sol 2090: Drive forward in 2 steps of 2.5m, ended early after 1cm forward motion limit reached Sol 2092: Drive forward in 2 steps of 5m, ended mid-drive after RR stall Sol 2095: Drive forward 1.5 m for RR diagnostics, indicate RR works Sol 2099: Drive forward in 2 steps of 5m, aborted in RR stall after 1.5m of wheel turns Sols 2104-5: RR diagnostics at cold, medium, and warm temperatures Sol 2109: RR diagnostics show elevated resistance and no motion Sol 2113: RF wheel shocks everybody by rotating a little; other tests indicate electrical short to rover chassis Sol 2117: Right-side diagnostics: RF rotates normally for 3 steps; but failed during 4th; RR did not move Sol 2118: RF diagnostics indicate intermittent functionality; RR nonfunctional; drive forward unproductive Sol 2120: Drive forward results in left bogie angle increasing (LM lifted into air) Sol 2122: Drive to flatten left bogie doesn't work as planned Sol 2126: Drive commanded with all six wheels, 5 steps of 10m each; aborted during 5th step due to excessive sinkage; RR and RF did not rotate Sol 2130: Wiggle wheels before drive, aborted during wiggle due to excessive resistance to turn Sol 2132: LF, LR, RR steered 60 degrees inward then forward to try to scoop and pack soil before drive; aborted during steering due to excessive resistance to turn in LR wheel Sol 2136: straighten wheels, drive 4 steps of 2.5m each, toe in RF to align treads to hoped-for direction of rover motion, drive 4 more steps of 2.5m each; terminated due to excessive sinkage Sol 2138: A drive, not yet described on JPL website.
They seem to be trying more and more "creative" approaches to extrication -- here's hoping one of them works!