Bill, I wouldn't worry too much. If aluminum is being scraped off the wheel, it's got to be worse here on the solid rock than it will be in the loose soil, and how much bedrock like this are we going to see again? We probably have a long way to go before things get bad for that reason. Alternatively, let's dance a jig here and wear the whole wheel off!

Phil

I would say that *both* cases are caused by transmission loss. The pictures referred by Bill (in these two frames: 1, 2, I presume) have a sharp border because they are LOCO (no, no, not crazy, just LOssless COmpression ). The fuzzy border is seen only on those pictures with heavy compression applied, which is the normal situation but not on this case.

Data loss, twice? On both images?
http://qt.exploratorium.edu/mars/spirit/pa...QWP2537L7M1.JPG
http://qt.exploratorium.edu/mars/spirit/pa...QWP2537L7M1.JPG

http://qt.exploratorium.edu/mars/spirit/pa...QWP2536L5M1.JPG
http://qt.exploratorium.edu/mars/spirit/pa...QWP2536L5M1.JPG

Agreed, Phil, we can run her til the wheel falls off. I was cautiously speculating on something that I wondered about last year when our "three legged dog" resumed her trek. I suppose that it might even drag better on loose material if the "treads" were worn off of the bottom of the wheel.

I didn't mean to seriously mention the "C" word. I'm sure that there is nothing sinister about the odd data loss. Although I'm equally sure that they are having a field day with it at the Gelbe Platz down the street...

--Bill

Apparantly. At least, they've been filled in now.

A very nice reflective trail across the lower part of this pancam view. I particularly like the barely visible trail of glints from the rolling wheels across the very bottom of the frame.

Speaking of trails, I also really like this navcam view of the U-turn Spirit made around sol 1350. She came remarkably close to the steep dropoff at the edge of home plate!

That is cool. Perhaps they will title the image "Thelma and Louise Reconsider"

I'm really surprised by this trail of aluminum. The hardness and abrasive character of those rocks must be substantial. Of course if you've ever hiked across basalt you'll know the damage it can do. I once took an ill-advised off-trail hike through Craters of The Moon National Park in Idaho and after only an hour and a half the sole of one boot was flapping up and down hanging on by just a few threads. I don't expect a dragging aluminum wheel would last very long in those environs.

I'm not convinced this is scraped off aluminum. It could just be smoothed areas giving specular reflections of sky, or just uncovered areas much lighter in albedo than the surface. However, home plate is already quite bright, so this latter possibility sounds not too likely.

The rover masses 185kg. Divide by six wheels. Divide by three, for Mars gravity.

Picture dragging a ten kilo, 25cm diameter, aluminium wheel over rocks...I think the cleats would wear quite quickly, but I can't imagine much damage being done to the main "tyre" over short distances.

Andy

If this were scrapings of pure aluminum, or a pure aluminum alloy, putting the APXS on it would reveal it in an unambiguous fashion. I'm sure the rover team would be interested in finding out if this is happening to one their wheels. They probably already know the answer, they just don't want to tell us.

Even though I brought up the supposition that the satyrated areas might be wheel scrapings, I think this unlikely. I'm sure that there is some wear on the wheel being dragged over the rocks, but not ehough to leave a "streak".

We'll find out one of these days. Another strange happening in this corner of the universe...

--Bill

IIRC my metallurgy training (going on 30 years, not a sure bet at this point [laugh] ) it would take pretty sharp tooling of a specific shape and 'angle of attack' to generate chips. Can't help but think dragging an aluminum wheel on hard rocks is going to yield small particles pretty much exclusively.

New L257 and R721 Pancams of a couple of these saturated areas are down within the past couple of days. Without a quick "handlens" view to confirm, I'm thinkingt that these areas look like a drusy coating on fracture surfaces of the rocks, which makes sense consdiering the hydrothermal/epithermal nature of this area.


--Bill

Extending the topic of interesting rocks on the surface of Home Plate, which I would hope are worthy of IDD examination as we make our way toward the 'north winter haven', to whit:
It appears to me that we have here a rock that has been split along a fracture plane by impact with the stuck wheel. This would be a fine opportunity to analyze the interior of the rock without needing a RAT. Just a quick brush and Bob's-your-Uncle! Since we have made the decision to winter on the sunny north slope of HP, we are within a few sols of easy traveling to get there. This leaves us months to explore the fascinating rocks all around us!

On that note have any of you code-friendly types managed to work out the identity of the rocks being referred to in the recent manager updates? E.G. Conundrum Peak, Pikes Peak, Mt. Sneffles, Mt. Eolus, Humboldt Peak, Gray's Peak, Elk, San Juan? JPL hasn't yet released labeled images.

P.S. How many would agree with me that the stuck wheel may just be the best thing that ever happened to Spirit?