Actually - that's a good point. 1183_0000 HRSC ob has Vic and Ithaca in it.

Meanwhile, from HRSC view. - indicating something like 250m of elevation change from the rim to the floor. I'll have an animation session with it tomorrow night.

Doug

I'd just like to toss in the observation that Spirit first showed signs of increased current flow to its failing wheel motor when it arrived at the foot of the Columbia Hills at about Sol 258. By careful handling of her roving, it took nearly a thousand more sols for the wheel to fail, and some of the mileage put on her in between including scrabbling up to the top of Husband Hill.

Just because Oppy is showing signs that her already lightly lame wheel is beginning a slide into failure, is there any real reason to anticipate this failure occurring in a far less number of sols than it did between first symptoms and complete wheel failure on Spirit?

-the other Doug

And how many km. (answer, not that many)

Now how many km to Ithaca. (answer, many )

So, if you want to consider a 20km, then yes - there are real reasons to anticipate this happening 'sooner' than it did on Spirit.

Doug

Can't find that map...do you know where it is Doug?
That image you posted is quite awesome, never seen it before, could you pass some more info about it? Is that the maximum resolution? And a legend for the colours does it exist?

It's from here : http://hrscview.fu-berlin.de/cgi-bin/ion-p?page=entry.ion

Doug

Thanks Doug! And slinted...and algorimancer...
The puzzle, with the current available images, is almost complete:

Oh, I'm not saying that the wheel ought to be good for a 20-km trek. I'm just wondering why, at the very outset of a problem that took two Martian years to progress from initial symptom to complete failure on Spirit, we seem to be hearing "Oh, my, will the wheel last long enough for us to get out of Victoria?"

Shouldn't we anticipate that, for example, Oppy ought to be able to putter around Victoria and its annulus for another Martian year or two before its wheel locks in place, rendering her still mobile but much slower and unable to handle steep slopes?

-the other Doug

Another year or two, or maybe just another month or two, or maybe tomorrow. We don't know. We're guessing. You should be thinking km's, not years though I think. What is most probably is that it will fail at some point, and the middle of a dune field probably isn't the best place for it to happen.

Doug

You guys help the dumb here with the maths...EDITED: forget it, got the answer already...

Bridges...terrasses...there must be an abyss here somewhere...

Sorry Ustrax, even if Oppy made it to the near rim of Ithaca, any abysses in those features are still several years of driving away, even without the scientists wanting to do their pesky poking and prodding. And surely, we would want to take the time to climb one of them big hills on the near edge.

I'm wondering, now that we have Doug onside for the Ithaca trek, does that mean the dreamers have simply worn down his resistance, or does he know something he's not telling us?

Personally, I like the crater due west of Victoria, about two "endurances" away. It is closer than Ithaca, seems to have a nice path of etched terrain to follow, and the closest rim appears to have good exposed layers deeper than Victoria, assuming the slope is traversable. Has this crater been discussed in past speculations? Have we given it a name yet?

Brian

You don't really. What I've said is that there are many valid science targets in the Victoria aria, even back up to Erebus etc. Once all of those are exhausted and no other options are available, then a not-quite-utterly-horrific-but-still-idiotically-lengthy route to Ithaca would be a valid next step, if for no other reason than to cover ground in any direction.

Doug

I agree that a nondescript dune field isn't the optimum place for Oppy to become a stationary lander mission. The only thing I guess I'm taking exception to is the comment "We don't know. We're guessing."

Doesn't it make sense that, with an entire failure sequence with which to compare (of identical equipment under similar environmental circumstances), we *do* have the ability to do more than guess? Isn't there a certain amount of engineering rigor to making meaningful projections of the eventual failure of Oppy's wheel based on the observed failure of Spirit's?



-the other Doug

Let it be noted in the log of the starship Enterprise that I here voluntarily relinquished my opportunity to leap in with both feet punching, in deference to "nprev", who can better render justice from the font of technical engineering expertise.

oDoug,
We just can't make any statistical inferences based on only one sample point. Sure, Spirit lasted a good long while, but that doesn't tell us anything about Opportunity, simply because we don't have enough information, ie look up Law of Small Numbers. Even if you argued the 12 wheels are enough to give us some statistics, we are stuck because we would be comparing their first 1500 sols against their next 1500 sols, which are obviously very different.

If we had numbers on average time to fail at 3000 sols, then we could give reasonable estimates. Given what we know now, what a good engineer would say is that if we had a new rover, the odds are good we could make Ithaca. Beyond that, it's all hand-waving.

Even comparing the testbed rovers here on Earth wouldn't tell us much, because the environment here is so much more benign than on Mars.

I agree with Doug, explore the hell out of the nearby environment, and only then go for a suicide run to Ithaca. At least we would get another year or two of worthwhile scenery before the long haul.

Well - here's the Spirit story. It failed a bit, then we nearly stopped using it, then it was fine for a while, then it suddenly died totally. It was, perhaps coincidentally, the trenching wheel that died - but all 6 wheels did a whole LOT of trenching on Opportunity. Opportunity has a stuck steering actuator that may or may not make a contribution. Opportunity has done a lot more mileage, but probably less climbing, Spirit has had hasher thermal cycles, but Opportunity's probably had more jarring driving over open rock. To infer 'we've got X sols' or, 'X km' from that is a random guess.

Doug