A similar thinking (?). I know Spirit is not fast moving but, anyway, is there any interest after having moved material, to back a bit and then drive "full speed" to "jump" a bit on top of the moved material?

There are lots of interesting details in the latest Planetary report. Here are some highlights:




So 50 cm to clear Belly Rock that we heard from Maxwell does seem to be high.

The RR wheel stalled again on the sol 2099 drive after only 1.9m of turning.

http://www.jpl.nasa.gov/freespirit/index.cfm

As long as the material moved goes from the front of the wheel to behind it, sure. Material from under the wheel to behind it would not be as useful.

7 posts that start from an off topic moan all deleted.

http://science.nasa.gov/headlines/y2009/02...y.htm?list15891
I know this is old news, but I just made the connection between sulfates coming from vent activity and the crater's edge Spirit is sitting on. What are the chances the crater is an ancient vent? Or is the sulfate a layer in the hill that the crater happened to punch into? Could the RAT gum its way through the duricrust? (haha, just had a thought of adding a small aircannon or railgun on future rovers to punch through duricrust with BB's at range in "danger areas". That could go along with the laser on MSL! )

I'm wondering how much material is being 'squished out' to the sides of the wheels. Is that critical? Insignificant? Can it be used to any advantage? And if we drive with less than all 5 wheels would this allow positioning of the rover (yaw) with significantly less sinkage?

IMHO this isn't looking too good, but I don't know all the specifics of what's being done.

What has the team learned from this embedding that is going to be applied to the next rover? I would guess something to do with wheel/tread design and perhaps an active suspension that can lift and reposition a wheel/motor assembly? Why not have a tow cable on the next rover? Why not have a way of shifting terrain around to change traction and terrain features directly next to the wheels?

The JPL team takes 3 MI images of Spirit's under-carriage after each drive.
One is leftward, one center, and one towards the right (with respect to looking back under the rover with the MI camera)
The right view is towards Scamander crater.

Here is the left view MI animation, Sols 2081, 88, 90, 92, 95, and 2099.

Click to view attachment

Cheers

According to table 12 of the tracking site report, no data has been recorded to flash since sol 2100. It appears that they can still transmit data from before sol 2100 so I'm not sure of it has to do with Odyssey being in safe mode or another memory error.

Next drive (or diagnostics maybe?) is scheduled for sol 2104/today. That's how I read the date in the tracking web even if the official MER site has no new info after the stalled drive during sol 2099.

A quick thanks to all those interpreting the tracking site info and posting the news here, really good to know...

Eoin

And another drive is scheduled for Sol 2105 ? "Penultimate" and "ultimate " for front and rear hazcams.

From TPS report, I've found this very puzzling:

"Laubach summed up. “We saw significantly less sinkage than on the prior couple of drives,” she added. “But the numbers are very, very small and so it's very difficult to tell. There's a lot of noise in our sinkage measurement, meaning that we're measuring things on the order of millimeters and the uncertainty in our measurement in on the order of millimeters.” That means that it could be Spirit didn't sink at all. Or it could have sunk more than they thought."

As we've all seen, the LF rose quite a bit on the 2nd attempt (or was it the 3rd?). Anyway, my question is: could it be possible, because of such small numbers, that the rise from LF has been interpretated as sinkage? I mean, if the front rises, the rear lowers.

Thanks PDP, what I take from that is that Spirit is still making millimetric progress. Eventually, probably, she'll be clear. The wheel pics tell the same story: she's slowly eating her way through the piled-up dust of her inward journey.

As I understand the suspension system, the middle and rear wheels are directly connected so if one rises the other lowers. But the front wheel can rise and fall independent of the motions of the other wheels. So you can't really know what the other wheels (or the rover as a whole) are doing by looking at the front wheel.

The individual motions of six wheels that would contribute to rover sinkage is certainly complicated. In any case, as pointed out in the update, the changes are so small it's hard to tell if any individual sink in rover elevation is real. There does seem to be a trend though.

Here is an animation through the right rear hazard cam of the extrication so far.
It spans Sols 2072 to 2099
I have processed out the shadows.

Click to view attachment

Cheers

Details of the current plans from the latest update:

Is it just an illusion, but does that RR wheel look turned nearly perpendicular to the LR wheel as it emerges from the soil?

I see what you mean! I think that it is an illusion, my take is that what 'emerges' is soil churned up by the RR wheel, the wheel itself is behind the bogie arm and totally buried.

Sol 2104 RR diagnostic rear hazcams are down. I don't see any sign of motion in the surrounding soil, but the RR movement was supposed to be small.
http://qt.exploratorium.edu/mars/spirit/re...cam/2009-12-04/

Here is an animation from the right front hazcam of the extrication.
It spans Sols 2072 through 2099
The contrast has been enhanced and shadows diminished.

Click to view attachment

Cheers

hi read around that there is a SW onboard Spirit which allow determining if wheels are slipping when rover is moving, by comparing odometer to hazcam pictures; but I also read that this SW has been disabled for some reasons!
Is that true? I can't find any link.

AFAIK, that's visodom (VISual ODOMetry) and it certainly is being used; it's not "disabled".
Two corrections: it uses navcam images and the "slip measurements" are not done while the rover is moving but after it is already stopped by comparing pre-drive and post-drive images with the odometry based only on the wheel turns.

While we are all waiting for further Spirit extrication news ...
here is an animation taken from the Left Rear Hazcam for Sols 2072 through 2104
The contrast has been enhanced and shadows diminished.
I finally built a little batch file that does all the rigmarole to do the enhancements
(10 mins from raw images to finished animation)

Click to view attachment

Cheers
(it is snowing in New England tonight, 2 inches so far...)

John Callas on NPR's Science Friday Dec 4, 2009:

http://www.sciencefriday.com/program/archives/200912042

Thanks for the link. He says if we can't tilt Spirit to the north, there's a "real risk" she won't survive the coming winter.

Can they tilt (in some way) Spirit to the west, away from Home Plate?

Tilting deeper into a sandtrap? Not a good idea.
If your intention was to get away from Belly Rock (aka Pointy), it has already been suggested that it doesn't look like it will be big issue.
No official word yet, but Spirit has a long way to go.
Best way to get a gap between Spirit and Belly Rock is to continue doing what they're already doing...drive forward which will take Spirit up and out

Remember to read the Spirit Extrication FAQs

I thought that, with the recent cleaning events, we were likely to survive the winter at this spot. Has this changed?

Hungry: we've been accumulating dust since the last big cleaning events (dust factor has decreased from almost 85% to 57% in the latest report).

Hertzeg: It's an interesting thought. If sinkage turns out to be a problem as we try driving out, we may end up inadvertantly testing something similar to your suggestion. As Astro said, it seems likely that Belly Rock is floating on the powdery layer rather than on the firm ground beneath. So the best strategy is to keep to the right (east) as we drive out, so if there is firm ground below within reach, we're most likely to reach it. You'd think it'd be good to have wheels hit hard ground below. But actually I'm not sure what would happen if we did. The wheel would still have to move powder from in front of it to behind, and would that be easy with hard ground immediately below the wheel?

The regional dust storm that started around sol 2000 dropped the dust factor (the percentage of sunlight reaching the solar panels) from 0.844 to 0.614 over the period of about a month.

Oww, okay. Thanks for the info.

Is Dburt still about? I'd think he would have a comment or two.

You rang? At this point I'll just guess that the tiny crater in question, like Home Plate itself, is unlikely to be a local volcanic vent, because local vents generate nearby coarse ejecta, and repeat myself that all of the bedrock at and near Home Plate appears to be continuously layered, with bedding lying sometimes at surprisingly steep angles. Sulfate concentrations vary in a mysterious manner that suggests some kind of complex post-depositional redistribution mechanism, perhaps involving surface moisture, freeze/thaw, evaporation/sublimation, and wind (hope that's vague-sounding enough ).

---HDP Don

I was thinking more along the lines of a fumarole than an actual lava-spewing vent. That would explain the high concentration of sulfur inside the vent. The material inside might still be windblown dust, just picking up sulfur from deeper in the fumarole stack. Not implying it is active either, just a source of sulfur that can be moved upwards towards the surface via chemical reactions or minute water traces.

Thats nice and vague thanks! If it's a meteorite crater might the presence of the sulfates in the crater tell us something about the redistribution mechanism? If the sulfates and the crater are related, and its not just a coincidence that one is in the other, then without knowing how else the sulfates might have got there the idea of fumerole seems (to my very limited geology knowledge) to fit. Mods I won't ask any more questions on this subject after this post, I've no wish to derail the thread.

HDP has his own very lengthy thread for his ideas based on the MER results - discussion should be in there.

In the latest Spirit update there are details on how the 2104/05 RR wheel diagnostics went.

I'd guess they're probably gonna try to run the wheel in the opposite direction a bit to see if it rotates at all, of course, and also to try to dislodge any foreign object that might be stuck in there.

Hey nprev,
Burning out a wheel actuator that is buried (see animations) ... and who knows what is clanking around in that wheel cavity... may force a prophylactic shut down of that wheel (RR). This may force a crab walk towards home plate to get the left front wheel on solid ground, that sets up a slogging pull out of Scamander. After all that, a full evaluation of the RR could then be done at leisure ... after the rocks fall out!
But with my minor speculations aside, I hope the JPL team will deliver a mobile rover in the weeks to come after their combined hard work.
Cheers

Back to the present... I'm still seeing what appear to be new dust devil tracks forming out there. Here's an example that appeared between sols 2099 and 2104. The endpoints of the track are marked with the white arrows:
Click to view attachment
The lighting angle is almost identical between these two frames, so it is a real albedo effect.

Presumably this means is that there's still a glimmer of hope that we'll see some strong gusts at Spirit that clean the panels.

Or could it be a localized darkening due to the shadow of a cloud in the sky?

There were two F hazcam frames on sol 2104 taken almost 40 minutes apart, and there's no movement in the dark streak between them that I can see. Also frames were taken on sol 2105 and it looks like the streak is still there, although the lighting is quite different.

From a New Scientist story:

The latest blog entry on the Free Spirit website is Dec 12.....someone invented a time machine ?.....it's the 9th Dec as I type this.....

Perhaps this is the correct place to post this or not.. (moderators??)

Why didn't the mer design team use brushless motors? Most certainly the tech has been developed for the past 50 years and would prove much more reliable imho. Was it a cost issue? Weight/size? Power output/efficiency?

With 2 dead wheels on the right side I don't see how we can have a mobile rover, let alone escape from the trap.

Remember - they were only specified for 90 sols of driving, approx 600-1000 metres.

They have both done many many times that. So it's only fair to say that the motors have far outperformed their requirements.

Brushless are a newer technology, a more complex technology, and are heavier

http://starsys.spacedev.com/starsysproduct...rticle.asp?id=1

http://trs-new.jpl.nasa.gov/dspace/handle/2014/38930

For what was required - brushed was the proven choice.

I believe one of the "plan Bs" (or maybe "plan Z" for this one) is to try energizing the right front wheel again in the hope that it might somehow have started working again. They have said they are reluctant to try this because of the possibility that it is shorted, in which case energizing it might cause damage to other driving circuits. However, if the RR wheel is truly gone, there might be little to lose in trying that at least.

The problem is "what would be damaged if they try to energize the RF wheel?"
Would it be limited to the RF wheel control circuitry or would it extend to other areas like the IDD? If it's the former I would concur with you but I fear it is the latter and in this case we would lose almost all science capability and not only the driving.

They can't move both IDD and wheels at the same time - I think they may be tied on the same power distro. board.