Sorry for the flood of pictures, but here's one more corrected view that makes it easy to see how much they pivoted around the RF wheel:



About 45 degree yaw. I take back what I said... the situation doesn't seem too bad; they can probably just back straight up with no problem.


I'm just guessing like everyone else. Looks to me like one of two things happened. Either they lost traction on the right middle/rear wheels (the ones leading the stuck wheel as they drive backwards), and the other 3 wheels pivoted them around the dragging wheel. Or the stuck wheel snagged a stubborn subsurface rock. Either way, you need to back up, change direction a bit, and move along.

Presumably this kind of occurrence will be common from now on. I would think JPL is working on algorithm enhancements to prevent and/or automatically recover from situations like this so they don't lose driving opportunities.

Navcam mosaic from from Sol 781, showing where we started dragging:

I don't know - look at the hazcam pics in the drive direction. It looks like they might have made an intentional end-of-drive turn.
And look at the tracks - they are fairly straight despite the draggin wheel. It seems like they're compensating reasonably well, possibly with a modification of the previous 5-wheel mode.

With the wheel now turned completely sideways. How much stress can the wheel take? Is there a chance that driving with the wheel turned sideways like this rip the wheel off?

http://qt.exploratorium.edu/mars/spirit/fo...74P1209R0M1.JPG

And if Spirit did lose the wheel. Can it drive ok with 5 wheels???

Hope for a Dust Devil soon also

I can't believe I'm saying this again....there is no evidence that a dust devil ever cleaned Spirit. Some of the cleaning events happened overnight. You don't get DD's at night. Further more - the fact that there was a clear lack of cleaning 'downwind' from the HGA shows that it wasnt a spiralling whirlwind, but simply strong local winds in a constant direction that cleaned Spirit.

What we need is a big hill - the sort of place that has strong winds - not a DD - not to mention the fact that the DD season is long finished.

Doug

Doug,

Your comments sound interesting. I have never heard about strong winds other than DDs? Do you have any info on this?

Listen to or read the Steve Squyres Q'n'A I did .

http://www.unmannedspaceflight.com/index.php?showtopic=1683

Doug

I wonder - doesn't the dragged track look a bit like the Magic Carpet?

I thought exactly the same thing.

I don't think the wheel has turned sideways. What has happened is that the Rover has slewed around so that it is sideways on.

delete

Is there a topographic/contour map for this area - the last I could find on the MER Mission site stops before Homeplate?

Andy

I have a pair comments about Spirit's new situation.

First, I am thinking a possible better solution to minimize the dragging of the front right wheel is that the rover don't go straight in comparision to the troubled wheel but try to go in the same line as the troubled wheel. That is in order to minimize the width of friction. That is only a tought.

The other comment, the dragging wheel would provide a good chance to know better the different types of land: dark and light color which is the indication of the different degrees of sulfate process.

Meanwhile, I hope that at any moment the friction force will turn on again the troubled wheel during its struggling dragging.

Rodolfo

I think you might be missing the problem. The problem is driving the wheel, not turning it. They can turn the wheel left and right, i.e. have it in the direction it would normally be for driving. What they can't do is DRIVE the wheel.

For comparison, Opportunity has a wheel that is steering-locked just off centre, but still driveable - and they're doing quite well with it.

Doug

Good for the clarification. Thanks

Then why the wheel was not aligned to the direction. Let suppose that unaligned wheel was leading greater friction on the surface. From this view, I am re-thinking that the diagonal position (45 degree to the motion direction) is the best position that minimizes the friction because the wheel surface has small "carets"? that is perpendicular to the direction.

Rodolfo