The layering stratas are only visible when the outcrop is clean of sand. This only happens from the top down to few meters. Hence, the Oppy will be looking for any Bay which has ram of outcrop. On that, Oppy will be able to drive down to study the surface and also be able to get back. It is not worth to continue going down when the outcrop is covered by sand. What return of science will be?

I suspect that the Duck Bay there is a good outcrop ramp. Then, I see that JPL is going to take full Pancam from both Cabos in order to inspect better the surface conditions.

The other point of my toughts: It is evident that Endurance has much outcrop and the inside has less sand deposition. It might be related to the younger age than Victoria Crater or the zone of Victoria Crater is more windy or that zone has more basaltic sand that had already deposited inside Victoria Crater.

Rodolfo

Diane, hear hear...I think that an extremely conservative approach to the decision whether or not to enter Victoria is entirely appropriate.

In my opinion, it is much more prudent in many ways to forego entry if any significant possibility exists that Oppy cannot exit, much less enter safely. There are other targets to examine in the Meridiani region and the serviceable lifetime of the vehicle should be the limiting factor for the mission, not its environmental circumstances.

Bottom line: there has to be a rigorous risk vs. Opportunity evaluation (ta da, da!) before making a decision either way, and this decision should be driven by both qualitative and quantitative scientific return potential considered over the course of the entire mission.

There is still a lot to consider about this crater, and there is time available for consideration. Here are some of my thoughts. I am convinced Opportunity will go in, but not until some circumnavigation has been completed. The most favorable slopes for entry seem to be on the far left and right of the imagery available to us. I particularly like some of the possibilities seen in the newly revealed areas from the left-most recent navcams, but there also seem to be some possibilities in the right-most recent navcams. I must guess that the left-most and right-most views are seeing the slopes more edge-on rather than face-on, so they suffer little from foreshortening.

To me, the imagery available so far suggests that if we do at least a partial circumnavigation, we will find many opportunities to safely enter and exit this crater. Then, considering the fact that several of the influential team members controlling Opportunity are experienced rock climbers, what else would you expect?

Remember that a hypotetical entry ramp will be constrained not only by its steepness but by sunlight availability.

My feeling is they will do a sort of mid-term planning like dedicate the next X months to circumnavigation, mapping and remote sensing (all pancam filters) and then, when the power situation is better then now on mid-winter, proceed to the selected entry point.

I quite agree - which is why we have to look at the entire crater to identify the best place to do it, from a navigability, sun slope, and exposure accesability perspective. I would be amazed if we ploughed straight in at Duck bay without seing it from something like 90-120 degrees around the crater first. And in actul fact, I don't think we WILL go in at Duck bay - I think the safest place for entry is on the SE side. The slopes are less, the outcrop is more exposed, the slope would be good for winter, and UHF comms should be a little better.

The same treatment as with Endurance is the very least I would expect.

Doug

To clarify on a couple of things, yes, I do want to go into Victoria. I also don't think that there are other scientific goals beyond Victoria within any reasonable expectation of Oppy's lifetime. The probable limting factor on Oppy is battery recharge cycles, for which we may get a few days warning, or perhaps a few weeks if Spirit's battery goes first. But if the arm fails in a deployed position, we may get no warning.

However, once we go in, we shouldn't count on getting back out. And short lifetime or long, we need to do the survey from the rim to know what we're getting into, and what the full context of Victoria really is. We haven't even seen half the rim yet!

There is no reason that GOING IN needs to be such a big deal! If there is an easy entrance to an outcrop such as on either side of Duck Bay, go in, check it out and leave to continue the circumnavigation.

I think they will navigate less than 1/2 way and probably no more than 90 degrees around the perimeter before making a decision. The ramp they choose to try may be a little further along that circumnavigation but the decision where to try will happen sooner. Any clear oppportunity to RAT on rock that is clearly older than what Endurance had to offer will likely be the driving factor.

Here is what today's Washington Post article had to say on that topic:

"Opportunity, which is the size of a riding lawn mower, cannot go down into the crater right now because it is winter on Mars, and the rover's solar panels would not receive enough sunlight to power its motors or operate the radioisotope generator that keeps the robot heated when temperatures plunge lower than 100 degrees below zero Fahrenheit. But the shortest days of the Martian winter have passed, and the long spring and summer lie ahead. The Martian year is about twice as long as Earth's, as are all its seasons.

Squyres said that the terrain approaching Victoria Crater has been relatively benign, and that ultimately driving around it is plausible. NASA scientists say they expect the rover to remain at the crater for months.

"This crater is so much deeper than what we've seen before, and that means much more geologic history is exposed in the rocks," he said. "For a geologist, this is just a dream come true."

It's that "leave" part that's raising issues.

The other issue is how far... The other side is at least 1.5 km away considering snaking thru all the capes as well. That's a long way for the little rover, and it could take months. There's a risk there as well that the rover might not last as long.

Well that's a weird comment, are they saying that solar panels would not receive enough sunlight to operate the radioisotope generator??

Another finger into the pie of decision making

Would you want to leave your rover for two weeks parked on a slope, or parked on the flat.

Doug

Are the north cliffs even in daylight or do we have to wait for the seasons to change for that to happen?

We haven't seen the near rim yet, which would be the closest possible entry point. The rim we've seen best is the farthest possible entry point. It's hard to imagine entry occuring without at least a 90-degree traverse, because you want to have seen the place you enter before you try the descent.

Consider WHY we want to go in. "Remote" imaging with Pancam and Mini-TES will experience better resolution, but only by a modest factor in comparison with a circumnavigation strategy. The real reason to go in is to perform IDD inspection which can only be done reliably on one descent path -- and certainly not on a serious cliff. So the goal here is not just to find a roadway -- the goal is to find a roadway that is also a VERY appealing target (series of targets) for the IDD. A sandy ramp to the bottom that left Opportunity stuck there would be almost worthless. And sheer cliffs, with the obvious rockfaces, are going to be impossible to IDD. There has to be a middle way, with exposed rock, but modest slopes, or there's scant reason to enter Victoria.

Now we have officialy 'arrived' and can see the dunefield i feel like no matter what happens now, i can fianlly die in peace (not that i want that to happen or anything).

Timeline:
We'll circumnavigate the rim for about 300 SOLs (after all, it looks about the same circumference as it is from VC to Erubus), im sure we'll get a really detailed DEM and map from all that observation, then drop down the chute at the best place for sampling the cliffs. sometime near 2008 well have a RAT of some part of a low cliff, if all is well.

and since Oppy is in good health, it should be no problem, especially if the solar panels 'receive enough sunlight to operate the radioisotope generator' (paraphrased from the washington post) ha! ha!