Sliding into 'Home Plate North', Heading for Spirit's 2008 Winter Retreat Options

[SpaceListener]

Incredible.

Now the previous stucked right front wheel seems to be freed by some kind of blocked small stone or oxides. After that, the wheel engine might have ended up by burning any winding core due to the extra force to overcome the stucked wheel.

Due to the high ratio of engine revolution to wheel rotation, it will act as some kind of clutch. However, if the rover goes slows, the troubled wheel might rotate as similar as the others ones.

I hope to hear any confirmation news about: Is the front right wheel rotating with propulsion or is rotating as a free wheel? I seems that the most probably case is of the second option.

[ilbasso]

fredk's photo of the recent drive seems to indicate that the wheel is still dragging.

[Stu]

I bet Steve and the guys are having a fine old time looking at the detail visible in the tracks and scuffs on the new images...

[john_s]

I don't know why, but I find these closeup images of the churned-up dirt really compelling. Perhaps it's because, deprived of their context in the Martian landscape, they look so familiar, like something you could see anytime on a dirt road here in Colorado. Then the realization that you are actually looking at another planet is all the more amazing.

Either that, or it's just fond memories of playing in a sandbox as a kid...

[djellison]

Is the front right wheel rotating with propulsion or is rotating as a free wheel?

Neither. It's not working, it's still broken - but the fairly unique situation of this nasty terrain has had enough of a drag on the wheel to rotate slightly even though the force required to rotate it (and the motor thru the gearing) is very high.

Doug

[Stu]

I know exactly what you mean John. I've been colourising these images quite a while now - succesfully for a much shorter time, I know!!! - but seeing those surface close-ups appear on my screen is probably more rewarding than seeing a big panorama or landscape take shape, and I think it's because the surface just looks so comfortingly familiar at such close range... you can almost smell the dirt, can almost feel the dust clogging your nostrils, can almost feel the stones and grit and grains sifting through and past and over your fingers as you trail your hand through it, can't you? When that image came up on my screen I just sat here and stared at it, imagining reaching into the screen, taking a pinch of that dry dust between my fingers and just rubbing them together... as you say, just like a big kid playing out on a dirty hillside during school summer holidays...

[elakdawalla]

That gear ratio Doug cited is a very powerful argument for some sort of clutch...even a simple emergency disconnect (pyro-fired guillotine that would sever the gearshaft?) that would let a stuck wheel rotate freely on future rovers.

This is triggering a vague memory of reading about Lunokhod -- I recall reading that the Lunokhods had a mechanism to free a stuck wheel, little pyros for each wheel, to separate them from their motors and allow them to spin freely. The things certainly had wheels to spare. Here's an archival Time magazine article that refers to it.

--Emily

[elakdawalla]

I was just checking MMB and this Pancam view from sol 1368 struck me as being rather pretty. Can anyone tell me if any of these rocks have names?

--Emily

[fredk]

John and Stu: my thoughts exactly. Very "earthy".

[CosmicRocker]

Emily: I don't think those rocks have any assigned names. Those images seem to be a piece of the third part of a panorama called "West Valley View" according to the pancam data tracking page.

As for the topic of the stuck wheel and the various options such as clutches, pyro-severers, etc; I am pretty sure we explored all those options and more, shortly after Spirit first lost the mobility of that wheel.

[fredk]

There's an extremely odd comment in the latest spirit update. After saying she broke free from the depression (called "Tartarus"), they write:

Team members are pulling out all the stops to get Spirit to a winter location where, based on solar power projections, the rover has a chance at survival. As the crow flies, that spot is 240.5 meters (130.8 feet) away. During the next few weeks, Spirit's journey to "Winter Haven 3" is expected to be no less difficult, requiring the rover to maneuver across a sandy, rocky valley along the western edge of "Home Plate."

First of all, WH3 is nowhere near 240 metres from here. More like a tenth that. Secondly, why on earth would they want to cross the valley to the west of HP?? A change of plans?

[centsworth_II]

First of all, WH3 is nowhere near 240 metres from here.

Thirdly, 240 meters is nowhere near 130.8 feet!

Using the 240 meter figure and westerly direction, it looks
like someone didn't get the memo that Spirit is not wintering
at Von Braun. Given the trouble Spirit just had in a little
sandy depression, I'd say it's an excellent idea not to try
and cross that sandy valley before winter arrives.

edit: Well Von Braun's not really West, but the press release
image here shows a location, Tsiolkoski, about 100 meters to the West.
I'm still sure they are not crazy enough to try and get there.

This post has been edited by centsworth_II: Dec 1 2007, 06:51 AM

[general]

Perhaps they mean something like this:

[Aussie]

[quote name='centsworth_II' date='Dec 1 2007, 06:24 AM' post='104871']
Thirdly, 240 meters is nowhere near 130.8 feet!

Emily got it right in the latest update - 40 meters (131 feet). But they were so precise with their 130.8 feet (referenced from what data point?) that it has to have been a conversion finger problem. Admitedly updates are not a risk area but I would have thought that NASA would have made any official use of non metric units an anathema following the loss of the climate orbiter.

[dvandorn]

I dunno, Aussie -- there are a lot of late-middle-aged baby boomers (like me) who were raised with the American versions of the old Imperial units, and we (well, at least I) have a hard time thinking in metric. I can *translate* into metric in my head (even conversationally), but I can't really think in it easily.

The more recent generations have been well exposed to metric, far more well exposed than my own generation. I mean, hey, when I think of changes in velocity for spacecraft, my "gut level" frame of reference is still feet per second, OK? But the kids these days -- they can think better in metric than I can.

That said, the purveyor of the recent update isn't having problems thinking in metric -- as far as I can tell, he/she is just having a problem thinking...

-the other Doug