Yes that seems like a sensible approach that ensures slower but sure & steady progress ... 50 meters at each driveable sol plus keeping the intermediate science stops short (like one week instead of 4+ weeks thus sparing the more complex science tasks and IDD hardware wear for the ultimate loooong science stop at Endeavour

The current status report has some tidbits related to that 30m drive and the current strategy:

RF wheel currents were beginning to trend upwards again so the drivers on shift decided to start driving backwards again and rest for a while.
There is some challenging terrain about 500m ahead and we will have to sit and think which way to go. This next resting period will come in handy for that.

Paolo

It does look tricky. My favourite route at the moment would be something like this, using patches of bedrock to move east and moving south when in areas where the drift material looks dangerous.

How about that! We are considering a path similar to that one but most of the drivers prefer a path that goes all around (westward) the area of Purgatoids that is just south of the rover.

Paolo

To my eye, angling south-west now, then proceeding close to the edges of the HiRISE photo south then east seems to offer the cleanest route to the really nice looking terrain in the eastern third of the shot. Is that the way being favoured?

Yes. Still the route has not been decided yet. We will use the next resting period to analyze the HiRISE in detail and come to a conclusion on which route to take.

Paolo

So, you don't trust Rui's! Realy?

> the next resting period ...

Is it at that outcrop 200m to the south?

No, I think we will stop at the end of the next drive. Wherever that might be.

Paolo

if I remember correctly, the increase in RF currents was less pronounced (or even non-existant) when driving on firm bedrock in the past (Paolo, correct me if I'm wrong) ...

What is the reasoning behind this? Is it due to excessive concern over the RF wheel currents, or because the future path alternatives diverge at this point? The reason I ask is that I would have thought it a priority to reach bedrock before stopping for any length of time (to maximize the science return during the rest).

Mike

The only thing that helped reducing the RF current now seems to be resting for a week or two. The higher wheel currents indicate that the motor is subject to more mechanical resistance. I have not been following MER-B closely but was told that the nearest bedrock is about 200m away. At the current rate that would be about one week of driving.

Paolo

Just catching up a bit. Drive direction mosaics for sols 1897 to 1904 (all images link to the same blog entry)


Sol 1897

Sol 1898

Sol 1900

Sol 1902

Sol 1904



James

I am suppossing that by driving on bedrock, the wheels traction will require less mechanical resistance than over the sand. Is there any difference of wheel currents between bedrock and sand?

The RF currents drop to almost nominal (~50% reduction) on bedrock but all other wheels change only a slight amount (10% reduction).

Paolo

Ah, this is very encouraging ! suggesting the RF problem will be greatly alleviated once we reach the firmer "parking-lot" type of terrain about 2 kms ahead (which is expected to be similar in driveability to the "easy" ground between Eagle and Endurance) ... so it sure is the most sensible approach to drive defensively in order to reach the "parking lot" with an intact RF

I thought I was looking at Spirit tracks. What the .... salts or silica in the middle of nowhere

Click to view attachment

Funny, isnt' it? The penultimate drive tripped the average wheel current limit which is in place to stop the rover when it is close to being embedded. This is the first time this limit was triggered while not extricating the rover from an embedding event. Looking at the tracks, I think this was a good thing.

Paolo

That's very interesting and very pretty
Click to view attachment

Hmm. I see some apparent slip marks in the white patch. Given the wheel current spike, is the white stuff therefore more slippery than standard soil?

(And does this hold any clues for Spirit's situation? How many kinds of white stuff have been noted to date over in Gusev?)

The little sliver of white to the upper left of the tracks suggests that we have ventured onto standard Meridiani bedrock with a very thin cover of sand.

Looks too clumpy to be just bedrock.

No I would agree with briv1016 that it is not bedrock. I think we hit a patch of crumbly salt nodules. I think the larger rock/patch would also crumble if driven over. Paolo also indicated that wheel current was up from moving over/into soft soil--I don't think you would get that with a thin layer of sand over bedrock.

I wonder if Opportunity will do any IDD work to explore the composition of the light material?

I don't see any sign of slippage in these images. The linear wheel track on the right isn't defined as well where it goes over the messy tracks from the turn in place. The lighter patches may just be patches where the compacted smooth fine soil is catching reflections of sun/skylight?

I certainly would be good to have something interesting and useful to do during a lengthy rest stop.

(If we're starting a powder vs bedrock debate , put me down for powder -- I hope it's not just wishful thinking.)

I'm wishing for the same thing, Cents, but after so many miles of bedrock without a speck of 'powder', I have to play the percentages.

Since we seem to be stopped in "DuneLand" for a while, perhaps we should investigate a dune a little more closely. We could perhaps penetrate a dune with the IDD and do some work inside the dune and/or at the point of penetration. Or would this possibly damage the arm?

You don't use the IDD for poking. But hey, when was the last time Opportunity dug a good trench? Lets dig down and see what's really there.

Surely, yes. It's the first such white material Oppy's encountered, and it's obviously a very different environment from Home Plate, so we surely have to find out what it is / how it got here, even if there aren't any implications for future drives. How cool that novel observations are still turning up!

It seems that this site was considered not relevant because Opportunity left the area. There was a drive yestersol (1912) moving the rover 70+ further south.

So, as I understand it, this is where we sit and wait to see whether Oppy turns on her left or right turn signal indicator? Good to see some chatter in the other thread about the possible choices. It's been pretty quiet in the back seat for awhile.

I think we've seen similar "white powder" on Meridiani before. I'm still skeptical it really was "white powder" - it could've been reflectivity rather than albedo.

But we did sit there resting the RF wheel for 6 sols, so maybe they decided the wheel could now survive a couple of sols' drive to the bedrock and then we'll do a longer science stop there?

Surely trench digging will not be considered given the precocious state of the RF wheel.

Could always use the FL. I'd expect us to do 1 - 2 more drives to get to the next bit of outcrop before having some down-time to make the decision between left and right.

I wonder about the extent of the "wear" on the other wheels, (not too far behind RF?) that would determine a "go for trenching".
I thought we would trade the digging(more resistance?) for driving at this stage...

The other wheels are all reporting normal currents.

I would expect that too but the plan for tosol has some MIs so perhaps we will be stopped here for some time.

. . as stated in post 60, no?

The Oppy has by far less watt-hours than Spirit.

There is increasing the concern on the RF which is increasing the wheel current.

More reading

Is there any way to improve the lubrication on the RF? Will the summer time, with the increasing heat might help to improve the lubrication on the wheels?

Yes, thanks to recent wind cleanings, Spirit is able to store about twice the energy Oppy is able to each day, but I doubt the extra amps Oppy's labored wheel may consume will break her bank. As I understand it, Opportunity's main concern is the mechanical preservation of that wheel system, not her available energy.

Just out of interest,did they ever venture an opinion as to what the white deposit of 10 June was?

It was apparently nothing of interest, since it was only observed in navcams, and no pancam filters or mini-TES observations of the scene were recorded. As I think was mentioned previously, these navcam-bright materials have been commonly observed in Opportunity's tracks many times before. A recent example was photographed on sol 1886, but this stuff has been seen very often.

I don't recall them ever being officially described or explained, which is why I assume they are a phenomenon well understood and of little current interest to the team.

According to Tesheiner's latest map I would dare to say that we are in great conditions to meet the estimated arrival date to my reference location or even get there earlier...let's see! Step by step...
Click to view attachment

That's because Opportunity took a short cut

We are almost at that big outcrop, less then 100m to reach it. And the big question is (hello Paolo!): left or right? Have a decision already been made about it?

That leaded to "The Spines"...

They sure didn't give any hint on this latest drive. I was hoping to see a fade one way or t'other, but they are maintaining the mystery. Ooh, I love a good page-turner.

I prefer a good wheel-turner.

Andy

This was quite a short rest stop - only 8 sols. Maybe Oppy's eager to see what the next chapter brings too...

I'm not sure if we're "back on business" or if the last site was just absent of any significant science feature and they decided to move forward looking for cobbles in the vicinity. Let's see what's in the weekend plan.