Getting Unstuck in West Valley Options

[nprev]

You got that right!!! Go, Paolo!

BTW, back in Montana during my wild youth I nearly high-centered a few times in slippery terrain. IIRC, any sort of tilt along the longitudinal axis is a huge help in extraction (since you're normally pretty level along the lateral axis in this situation).

[Phil Stooke]

"Is this roughly the right position?"

No, it's more like this:



Phil

[Stu]

SO wrong to laugh at that Phil, but I couldn't help it. You're a very bad man!

[Phil Stooke]

A very, very, very bad man! (waggles finger)

Phil

[nprev]

Well, if worst comes to worst, just land MSL nearby & program the SkyCrane to hover over & yank her out after it drops off MSL!

[Stu]

Well, if worst comes to worst, just land MSL nearby & program the SkyCrane to hover over & yank her out after it drops off MSL!

I think you're confusing MSL with Thunderbird 2...

[Guest_Oersted_*]

I suggest a new thread called "Getting unstuck in West Valley" or something to that effect... - This will take a while.

[imipak]

From an article Tweeted by MarsRoverDriver:

"This is a really big concern. We've never been in a situation like this when we've been at risk of high centering the rover," project manager John Callas said. "There is a real danger of it getting permanently stuck."

MahFL @390 thirded; you posted the words out of my head. Stu - my impression (FWLIW!) is that the front wheels (near side in your image) is a little less deeply embedded, and that the site's a few cm further away to the south. Been wrong before, YMMV, etc.

ISTR that after the first day or two of trying to back Oppy out of Purgatory didn't work, things looked pretty scary. In retrospect, that was mostly because it was the first time it'd happened, and the way out wasn't immediately obvious. Hopefully, the same applies now.

[djellison]

Now I wish I'd made building a 1/4 scale mobility model my Winter '08-09 project rather than my project for NEXT winter.

[RoverDriver]

???

Do you mean it was taken from a higher position (its from the edge of Homeplate) or that the location is wrong?
...

I meant to say that it looked like this pancam was aimed at a higher elevation, with the PMA aimed at an area that is visually above the NAVCAM.

What Sol is this? [edit: never mind, I see what sol # it is. Thanks!]

Paolo

[RoverDriver]

Here's a wild thought that would be more a later move of desperation. I'm not certain what kind of mass ratios we are dealing with but would it make sense to extend the arm and IDD to slightly shift the CG, and add to the traction/load on a preferred wheel or wheels?

The IDD is about 2-3 Kg and about 1m long, the rover is about 200Kg. You do the math. :-(

Paolo

[RoverDriver]

If anyone on the planet Earth can get us out, it is Paolo !

Thanks for your trust in my capabilities, but I have assembled a team that will actually do the work. Since we will be doing some testbed analysis, you won't see much changes in the scenery for a while, don't interpret this lack of mobility activity as unsuccessful motion.

Paolo

[RoverDriver]

I still believe we can rescue Spirit. The things that must be studied carefully are about the relieve of the soil around the Spirit. We must take the advantage of the help of gravity direction to be unstuck. According to Alan's picture, I am not able to see precisely about the inclination of the surface. As the rule of thumb, the lower land, has softer soil than the higher ones. The picture has show that the left side, close to the slope, the surface is very smooth but I doubt it would be a firm soil.

Is Spirit capable to turn around by 90 degree to change the scape route toward left side (close to the slope) toward the Braun hill?

Maybe, lower soil, has another kind of layer, a firmer soil which might help to improve the traction?

Brief description of the rover attitude:

1) the rover is aligned more or less north-south (front of the rover north)
2) the rover is on a slope about 10-12 degrees, left side of the rover is lower than the right side
3) pitch is almost zero

The soil under the left side is cohesionless, the soil under the right side seems to provide more traction.
The two middle wheels are only partly embedded, the RF is on top of the surface, LF, and rear wheels are fully embedded.

Turning in place was tried (CW) but was unsuccessful. We might try to revisit this technique.

Paolo

[alan]

I meant to say that it looked like this pancam was aimed at a higher elevation, with the PMA aimed at an area that is visually above the NAVCAM.

What Sol is this?

Paolo

The image was taken as part of the West Valley pan on sol 1367
http://marswatch.astro.cornell.edu/pancam_...WestValley.html
http://marswatch.astro.cornell.edu/pancam_..._L257_pos_5.jpg

[RoverDriver]

Is this roughly the right position?

http://cumbriansky.files.wordpress.com/2009/05/stuck.jpg

Roughly, yes. The roll of the rover is not very accuratly represented as well as the precise state of each wheel, but the position itself is quite accurate.

Paolo