Convinced or not, there's no way in hell they're getting 25 degrees from the bottom in the next two weeks - so from the top is the route.

Doug

I would back down, as then the PCMA shadow would be mainly over the front of the vehicle, not the arrays.

Doug

That last one is amazing - I wonder if it's the local fog, or the distant cloud that's causing it.

Ahh...err. my panorama viewer windows are now just empty - not even black, just the beige blankness.

Doug

I assume they'll be backing down the slope. Once they're on it - there's no way they'll be able to drive back up again. If I pick up, rattle, drop and shake my TV around - the dust on the screen wont move

Doug

I just don't see it working - I don't see it producing any soil stratigraphic record at all. I see it making a little furrow of mixed soil, in essence no better or worse than spirit's FR wheel.

If you want soil stratigraphy - do a vertical mission - a big arm - Phoenix style, or a drill or even just a more simple sampling tool (Pluto was good on Beagle 2).

Worth investigating - worth doing some tests on - but I don't think it's the right way of doing it and I just can't see it achieving what you want it to.

Doug

GLORY - that reminds me.. A (dim) glory seen on a layer of fog from a place called Symonds Yat in Gloucestershire, UK... and another sun-dog seen from a flight out of East Midlands Airport flying to Malaga

Thought I'd drop these into the Earth Obs section, as they're ... err... earthy

Taken from the front of our house this Saturday - Spotted the one 'dog' - then realised it was almost a halo.

Doug

http://www.telegraph.co.uk/news/main.jhtml...3/wchina103.xml

The two are obviously not the same image, and if confirmed, that extra crater is an astonishing find.

Doug

The man is a hard working genius - I was fortuante enought to be there when he got a medal from the BAA - and he's just getting better

Well - it's not going to.

I struggle to see what benefits (when balanced with the addition failure modes, mass, volume, power etc) a simple trenching device would have over the techniquie of lock-5-and-drive-1-wheel. We got some fairly good trenches that way. Having a constant trenching tool would be a complication and a restriction to mobility that I really don't think is necessary. Imagine a turn in place with a plough in the way - or the limitations to WEB clearence that would be incurred. Sorry - I just don't get it - look at the nightmare we have for mobility with 1/5th of the wheels screwed on Spirit. A plough will produce a lot more drag than a locked wheel and I can just see day after day after day of it getting stuck on things and/or breaking off. Springs etc. are not to great at -80 degrees - the metal doesn't really want to play that way.

What Spirit may have shown us is that there is a lot more value in playing scratch-and-sniff than we ever thought possible, so from a planning perspective, it would put in your mind the option to do a little trenching test at the end of every significant drive (the scuff in MER terms). But bolting something on the bottom of a rover to do it - it scares me half to death.

ExoMars is proposing to do this properly - a drill tool.

Doug

And the Port and Starboard wing surveys for the Shuttle

From http://planetary.org/news/2007/1130_Mars_E...ate_Spirit.html

"As we're driving backward, the middle wheels dug in and that popped the rear wheels off the ground completely. We popped a wheelie with both rear wheels. Both rear wheels were off the ground - Think this through," Squyres continued. Indeed. And picture it. "You've got a six-wheeled vehicle, but only four wheels are in contact with the soil. Of those, one wheel is dead. So now we had a three-wheeled vehicle."

Doesn't take any imagination at all to imagine a vehicle with only four wheels on the ground to load up one of them a little higher, especially on slopes. You're thinking in terms of steady state and static scenarios - this thing driving around is a dynamic situation when, given the variety of the terrain, momentarily almost all the traction goes to one wheel from time to time. I'm not sure quite what you're trying to get at really. It is a possible scenario, and indeed we have proof positive of that in a wheel that has been turned a tiny amount.

Doug

You've answered it yourself. It's not happened much - only a tiny tiny amount - and thus the peculiar conditions that could cause it have clearly just happened a few times.

Doug

Or, the 23rd, my Birthday

Doug

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

On the space multimedia website ( http://www.space-multimedia.nl.eu.org/inde...70&Itemid=2 ) is a lovely video of Peggy opening both hatches, drifiting into a dark Harmony, and turning the light on. It may seem a silly thing - but I don't think I've seen someone open the door, and turn on the light before

Doug

Nice anim - reminds me of the Navcam -all-day-long animations when she was parked up at Olympia. It gets ones brain into the topography as well. Very cool.

Doug

With the MER design, one always has to remember - if you want to add something, what are you prepared to remove?

Six clutches...check.
Now take off the RAT

Also - they are a failure mode of their own. Which is better - spend that mass, time, volume, money on making a more reliable wheel that wont NEED a clutch - OR - make a clutch that might lock 'open' and give you trouble on slopes? I can see the benefit of a clutch, obviously, BUT, I also can see images of Spirit, six wheels unlocked, freewheeling down the entire climbed slope of west-spur because of an 'oops' in the uplink.

Doug

Brilliant to see the results beginning to come out - can't begin to pretend I understand much of it yet - but I'll get there

I'll ask people

As I understand it - the gearing from the motor to the wheel is incredibly high - if it's anything like the HGA's motors it's >5000:1. So turning the motor by turning the wheel is hard, like trying to push-start a car in 0.000001th gear. BUt - given enough driving, over some particularly 'grabby' terrain, it looks like it's possible.

( http://hobbiton.thisside.net/rovermanual/ is a great page to look at)

Doug

I think it's rotated exactly one tread width

Doug

A bit close to the edge - but the edge is more likely to be solid rock to rove around - so I'm happy with that

Doug

That's GENIUS.

Doug

He's had to co-register multiple images shot in slightly different directions. What you're seing is one hot pixel that comes out white in every shot, moving around because he's shuffled each image around.

Doug