We'll not know all the possible places to rove down into Victoria before having a complete view from different angles. Anyway, we can already see that the far rim slopes look very sandy and can only hope the near rim behave better. It's not only a matter of % of the slopes but also about drivability i.e. hard surface instead of sand. Most of the discussions with the pictures we have today are about going/not going inside. I thought we need a thread for this and also think that we can post here all the studies and teh video that have been done when Oppy was about to enter Endurance.
As a start, and to challenge the idea, I (re)post what I think could be a ramp to enter the crater. It's situated in the bleu F1 Bay in James' map. The reason is that the ramp look rocky as compared to all the other ramps visible on the far rim. There's also a lot of rocks to study instead of going nowhere.
Click to view attachment

That ramp would look interesting to be inspected. However, due to lack of authentic color of these pictures, I am not able to difference clearly between the outcrop or sand. Waiting for a more L7 (infarred pictures) which shows better the outcrops...

Rodolfo

I think there are better choices on the near rim if the slope works out for traversability. The exposed rock appears to go down deeper and there seem to be more choices that maintain some northern exposure for power. O1 or P2 seem to present good possibilities. Even a NE facing part of the Duck Bay curve (around P5) could be good. I would put money on one of those.

Brian

Everything I've seen so far looks terribly steep at first glance. I know it is true that slopes, when viewed directly front on, often look steeper than they actually are, and I have expereinced this often when climbing hills. A snow gully can look almost vertical from a distance, and turn out to be easy angled at 30 degrees when you arrive close up. However the bays between the capes do look much steeper than the easily angled sandy slopes below. Any average slope angles we might calculate from crater depth and radius are not the whole picture - if the upper part is steeper, and the lower easier, then we are stuck on the outside.

There is of course a lot of science to do around the rim and it will be many months before the issue of entering Victoria arises. I notice the one year mission extension just granted is to be spent here at Victoria.

Kenny

How about something like this? Check out the slope on the right. Granted, we can't see what's below it yet, but that reminds me of the "ramp" that Opportunity used to get in and out of Endurance.

This kind of surface is of outcrop along with a little sand deposition. This slope is okay for Oppy's transversability in going down and also be able in retracting out and its distance would be between 5-10 meters below of rim. Around that there are interesting boulders.

Rodolfo

I think we will go in sooner rather than later. There is a growing awareness that the rovers are living on borrowed time. I would bet for early contingency samples below the rim at the "best" location for getting back out -- even if getting back out is considered to be risky. We'd want to do this in an area not far from where we are now, if possible. This is insurance in case we happen to get rover death in the next few months/weeks.

S.

I think a partial circumnavigation ( even if it includes toe-dipping excursions ) is vital to get as good a view as we can ( from both Pancam AND Mini-TES ) of the whole crater interior.

If we were to drive straight in from where we are now - we'd have no idea what we were driving in to, as we've not seen it in the way we can see the far side now. It is possible and perhaps even likely that the drive into Victoria crater is a one off...each metre driven into the crater might very well be the last chance to study that metre of layering. So it would be madness in my opinion, to not study the crater as fully as possible from the outside, before identifying the best location to study it from the inside.

And yes, the rover might die tomorrow - but realistically, I think Opportunity is going to be around for a little while yet - consider the hell that Spirit has and is going through - Opportunity has had it very very easy.

Doug

I'll agree with Doug. Into Victoria at this point would be a Kamakaze mission with so much to look at up-top. We've been here only a Sol and I've spotted a dozen spots I'd like a closer look at.

--Bill

Remember that the entry into Endurance began as a "toe-dipping excursion". The plan, after testing the footing, was to drive down the stack of exposed layers and then back out. There was no plan to drive across loose material to other parts of the crater when Opportunity first started down. They may well do some toe-dipping without knowing ahead of time which "dip" may turn into a long-term exploration.

There will certainly be an abundance of caution, including imaging of several slopes, and possibly some work on nearby rim-level outcrops, but the main goal at Victoria is to fully investigate deeper layers. Other investigations are secondary. Initial work toward that goal can be done remotely, but within a short time there will be diminishing returns, and you just have to put RAT to rock. A wander around part of the rim, with possible dips below is consistent with what was done successfully at Endurance -- and is the most likely approach to result in good science return. The big question is how bad are the slopes. If they consistently look risky, a longer rim presence is indicated. If we happen to find one that is deemed safe, down we go. That looks fairly unlikely though.

Scott

As I sometimes need to remind myself, context is (almost) everything. We really need some good views of a number of the cliffs to establish an overall stratiography for Victoria. Given Vicky's size and probable navigational issues, the best views of those cliffs will be from the tops of adjacent capes. We haven't even done that once yet. Without that, toe-dipping and sampling doesn't tell us much of anything about geology and history.

I'm looking forward to getting out on Cabo Frio and taking a long, hard look at Cabo Verde. That's when we really start to learn about Victoria.

The views are spectacular, but that's not what the mission is about. Understanding the geology is Opportunity's purpose. The geology is not likely to change from spot to spot along the crater. The best science will be gained by going deeper - not around. It's my opinion that a good entrance should not be passed up.

Having said that...

It is starting to look like there might be some very steep angles in some of the layers of some of the outcrops.

http://www.unmannedspaceflight.com/index.p...ost&id=7727

Nix posted that in another thread. If it is true that we are seeing angled layers, that would be very interesting to unravel...

ed

Angled layers pretty much mean one of two things, either big chunks have broken off, or something underground is pushing the layers around. There's not much other sign of mountain-building, so we can probably go with the broken rock theory. Besides the question of why the cliffs have collapsed, we need to understand whether the process of collapse has left Victoria in a state that may be risky for foolhardy rovers.

Crater fever is a really bad idea right now. Remember that we did a partial circumnavigation of Endurance before going in. Remember that Endurnace had rocky entrances, which Victoria doesn't seem to have. Remember that Oppy was on borrowed time during just about all of the exploration of Endurance.

Victoria really is a different crater from anything we've seen. What's the size of the smallest feature we can see on the far side? What's the effective range of the TES compared to the scale of the views we're seeing? How close can we get to the cliffs from above the rim, versus being down in the sand trying to get up-slope to a cliff? What is the difference in stratiography between the higest point on Victoria's rim, and the lowest? Is there a safe entrance point anywhere on the rim? How do we identify a safe entrance, and does "safe" include the possibility of coming out again? Once we get down into Vicky, how far up-slope will Oppy be able to move? How many of these questions have been answered so far?

If we knew that Oppy would die within a week, yeah, going straight in would make sense. But we don't know; it could be a week or six months or a year. It's probably going to be longer rather than shorter, we need a different approach to planning. The ideal would be a long-term plan that provides continuing payoff as we go. That's likely to mean low-risk as long as low risk brings payoff, and keeping options open.

To me it doesn't make sense right now to look much beyond our first really close look at the cliffs. That means photography and remote sensing, until we know what we're dealing with on the ramp surfaces. What we learn from both the cliffs and the ramps will determine what comes next.

Are those sloping layers within one outcrop, or are they sloping faces of cliffs, one in front of the other from this point of view?

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!

I agree with you Burmese, personally I would consider a full circumnavigation to be a waste of time and potential science returns.

But in addition I do think its a sensible thing to do only a shorter trek.

If possible, and I hope the planners will have the time, they could get a tremedously good piece of science return if they get Opportunity into position to do one ultra long Mössbauer integration during opposition of one rock outcrop now.
Well I know the odds are against it, yet if it would happen it could be time very well spent doing useful work when any commands cant get trough in any case - too bad our intrepid rover arrived so close in time.

Good comments, applauses.

Rodolfo

Getting in at Duck Bay may look easy but what about getting out again? The dune running along the edge could make that tricky.

Not only the improved angle to the sun would help, as you were hinting, but we might also get some helpful wind, like that back at Endurance which kept the rover almost completely spotless.