I'm looking more towards the tracking site then Exploratorium. It shows that images are downlinked on a sol way before the 5:00pm (local) afternoon communication session on Mars.

Right now for instance it is 12:45pm local time on Mars on sol 2212 and a good deal of images are already down according to the tracking site.


Edit: Odyssey's orbit was shifted last year to approx 3:45 am/pm local time. Still doesn't account for the early data returns though.

The data I can see talks about a single daily downlink session currently around 0100UTC.

Just saw this piece of information on the latest status report.

The right-front and right-middle wheel are exhibiting modestly elevated motor current levels, which the project continues to watch. The plan ahead is more driving.

Let's hope they don't get any worse than "modestly elevated".

One thing I've been keeping my eye on as we continue southwards is the S to SE horizon. Remember how we had a great view in that direction from Concepcion, then the view worsened afterwards. Looking SE now, towards Iazu, you can see that the horizon is looking pretty rough, which means it's fairly close:

http://qt.exploratorium.edu/mars/opportuni...1M1.JPG?sol2211

You can see the closer horizon start roughly to the south. It covers up the left side of the much more distant horizon in this image:

http://qt.exploratorium.edu/mars/opportuni...1M1.JPG?sol2211

Presumably the close horizon to the S-SE is a bit of a subtle ridge that's blocking our view of the distant horizon. Hopefully this means that once we reach this ridge we'll get a great view of Iazu and parts of Endeavour again.

It looks like we have about two or three more sols of driving before making a hard turn to the East. At that point I think it's safe to say that the ripples of any meaningful size have ended, and by the look of things I can't imagine ever encountering them again.

And after about 20 sols of driving we are going to start getting the view of the horizon back.

I think Oppy will turn East when she gets to a lane of bedrock about 250m South of San Antonio and this bedrock (The Yellow Brick Road??) looks persistent all the way to Santa Maria.

The distant views to Lazu, Miyamoto, et al seem a little more contrasty, so the air is clearing. The near horizon towards the Mule Ears seems a bit lower and I think that the near horizon towards Lazu will drop once we top that local rise.

Good road and nice scenery . Can life get much better?

--Bill

Another bit of a straight passage to the East on sol 2213: https://qt.exploratorium.edu/mars/opportuni...HUP1966R0M1.JPG

Between "Mule Ears" and "Rockaway" we've gained more and more space: https://qt.exploratorium.edu/mars/opportuni...PLP2412R1M6.JPG

That navcam image was taken on 2213, but before that sol's drive. So it shows the eastward jog from sol 2211. The 2213 drive was southwards:
http://qt.exploratorium.edu/mars/opportuni...0M1.JPG?sol2213

Aha, right: 1N324643261EFFAFHUP1966R0M1 / 2213 / 12:22:32

Looking ahead on the projected route in GM, I interpret the terrain as follows:

300 m Ripple size noticeably reduced (start of mainly eastward travel)
1.4 km Patches of larger ripples return amidst large stretches of exposed bedrock
1.9 km Larger ripples end, increasing amount of exposed bedrock
3.8 km Transition to "tarmac"
5.6 km Big hole in the ground that will probably slow Oppy down for awhile

More progress.

Not sure why but I like this image a lot.

That will be sol 2218 i.e. tomorrow.

And the wind has apparently increased. As I noted before, once we got past the wind shadow of the topographic rise at Concepcion, the ripple morphology changed with the suggestion of a wind velocity increase.

I have noticed an accumulation of dust in the low-gain antenna since the conjunction stopover at Santorini around Sol 1710. THsi dust collected as a ring around the top of the antenna and was persistent up to the arrival at Concepcion around Sol 2130. A recent Navcam view of the antenna on Sol 2211, after leaving San Antonio craters, shows that the antenna dust is no longer present.

I wonder if there have been recent cleaning events and what the watt-hour readings currently are?

--Bill

And what effect, if any, such an event may have had on the Mini-TES?

You're last image was sol 2211. Last week's Oppy update said:

That 227 level was continuing a slow drop. More importantly the dust factor also continues a slow drop, with some fluctuations from week to week. So it seems any changes on the low gain haven't been accompanied by big changes on the arrays.

From Scott

~250W-hr/sol as of last downlink.

We've been having generally a slow decline in power with small week to week fluctuations. That 250 Whr number doesn't tell us too much - maybe the tau dropped a bit from last week and dust factor stayed constant, or maybe tau and dust factor both increased a bit.

Evening all

There appears to be relatively little concern on this forum and the jpl site re the power levels for Oppy. Is this due to experience gained and a solar panel clearing event is anticipated/expected or is it simply that these things are in the lap of the gods and hence not worth worrying ourselves with?

Neil

Over the past six years we've observed The Cleaning Zephyrs breeze by frequently enough that we know that obscured solar panels are not an issue. I had noticed that a 500 Sol accumulation of dust on one of the antennas had disappeared and was wondering if a "cleaning event" had been noted also. This is sometimes related to the output of the solar panels, but can also be dependent upon atmospheric transparency and the annual insolation cycle.

I have seen some Pancam images of the miniTES calibration target recently, so maybe someone at JPL is hoping for improvement of that instrument. 'Twould be nice to have it back.

--Bill

The situation with Oppy is known to be more benign because she is closer to the equator, not by much but enough to make a difference. Mid winter is on the way but she'll bottom out on power before things get critical unless there is a major additional dust complication. Given that the SH winter season is a lower dust period (in general) the dust problem is not a major concern. That's not to say things aren't tight but that's how things have played out over the past few winters. If there is a positive dust cleaning event or two, then all the better.

I wouldn't necessarily disagree with fredk's assessment that the 250watt hour number is just a blip in tau but it's a pretty big jump from 227, it could well be an indication of a small dust cleaning event. We'll know soon enough in any case.

Bill/Helvick,

Thank you for your replies - a lot of good information for me there.

Sometime ago I stated my big fear was Oppy expiring 5 metres from the rim of Endeavour Crater - but now I feel a lot more confident and optimistic... I think we'll get within a metre now!

Thanks again, and as ever Go Oppy!

Neil

Short drive on sol 2220, aborted due to excess slip?
http://207.7.139.5/mars/opportunity/forwar...00P1211L0M1.JPG

That's was my thought too when I saw the picture. She moved "only" 10m.

Looking at the "right front" wheel in the FHazcam image, the first thought is "whoa, that's starting to dig", but looking at the (stretched, to see shadow detail) RHazcam image the corresponding wheel (on the left) isn't starting to dig in. Yet. So I don't think she's getting into trouble. From the virews from the Navcam and FHazcam, the soil has been quite firm and good to drive on since leaving San Antonio.

--Bill



Added: The Navcam of that track behind the "right front" wheel looks grim...

http://qt.exploratorium.edu/mars/opportuni...00P1992L0M1.JPG

Could it be that the RM slipped first then the RF slipped on the newly loosened stuff..?

The dunes are not very large here, so it's surprizing that she seems to've gotten bogged down a bit. And there was the episode soon after leaving San Antonio. It makes me wonder if the dune material (or crust on top) is getting softer as we head south.

If you look at one of the recent RL track images (will post a link in a sec after I find it), you'll see that all of a sudden the wheel starts sinking a bit in a low spot after hopping a dune.

It looks the the soil surface strength changed very abruptly; perhaps Oppy just drove off the edge of an evaporite crust? If so, doesn't appear to be any good way to discern those before actually driving over them since the dust covers everything.

EDIT: Found it.

We can just ask Opportunity's sister about that.

Based on this image, I would guess the observed difference in the surface strength is pretty local. (granted of course the tracks are being seen at different angles, that might throw off this interpretation)

The dunes in the area are dynamic and have become somewhat mobile. You can see more deflation with the formation of transverse dunes (ripples) and very well-defined laminations on the windward (eastern) slope of the ripples where there is more erosion. There is net deposition on the lee (western) slope and you'd expect the younger material to be, well, "fluffier" than the older, more consolidated material. You would expect to see this looser material to the west (left, in our direction of travel) of the ripple crest. As we run south and east, I'd expect to run into little "surprises" like this until the surface stabilizes.

It's rather like back when we were accustomed to the good traction of the mature surface around Endurance and ran into Purgatory when we got into the longitudinal ripple regime on the way to Erebus.

--Bill

I'm trying to see what's at the open space behind the RF wheel, i.e. between that wheel and the RM wheel on this fhazcam picture downlinked a few hours ago: http://qt.exploratorium.edu/mars/opportuni...00P1214R0M1.JPG
I can't see any cleat marks but possibly a "trench", is that right? Would it be an indication that the RM wheel stopped and was dragging the soil and so increasing the resistance to the movement?

Edited: Here's a crop of the area of interest.
Click to view attachment

If a wheel stops wouldn't the drive be aborted instantly?

No. IIRC a drive is aborted "instantly" if the motor current goes above a defined threshold.

I think you may be right

I really hope you're wrong, Tesheiner.

The left frame shows a bit more detail in the "trench":
Click to view attachment
There clearly is a trench, but it's not clear to me if there are cleats in it or not. There is a hint of a cleat in this left frame. At least the trench isn't perfectly smooth.

If the RM is still turning, but just digging in, then we wouldn't expect clean, well defined cleats like on a normal drive. Notice how the track behind the RF is much more chaotic and jumbled than a couple of metres farther back.

If the RM has stalled, then I'd think the trench would be very smooth. But maybe there would be some structure in it.

Basically, it's wait for more information...

A stall would result in a dramatic change in the current signature on the motor would it not? Something that would almost certainly flag up a drive fault.


Have we ever heard of a motor stalling, but the drive continuing regardless? I know that Spirit was using a cautious automatic system to recover from stalls within a sol, but for a drive motor to stall on Opportunity and yet the rover carry on driving would be highly unusual.#

I think we're just seing something of an NPE (Near Purgatory Event)

Note, in FredK's image - the 100% perfect track's just outside the churned material. The Front and Rear wheels have similar track width, but the middle wheels are slightly inboard of that. That clear track mark infers the FL wheel turning normally at that time.

Maybe its some soil properties experiment??

But then the latest update does say the right middle wheel has elevated current.

Agreed. And a Navcam from Sol 2220 suggests that the right Front and Rear wheels were turning and tracking normally and the right Middle wheel started to drag. The right Front wheel then began to churn and veer off to one side, as shown
on the attached annotated NavCam.

Nothing on Scott Maxwell's blog yet.

--Bill

It's pretty clear what's happened when you look at this navcam frame:
http://qt.exploratorium.edu/mars/opportuni...0M1.JPG?sol2220
As Doug said, the middle wheel tracks are normally inwards of the front and rear, as at the top of that navcam frame. Then presumably about a third of the way from the bottom of that frame, the RM wheel started to dig in (stall?), forming a trench (edit - dashed blue in Bill's pic). Then the RF wheel slipped into that trench, so it's track moved inwards a bit to line up with the RM track (dashed yellow in Bill's pic). Then the RR (not FL as Doug said) track was visible outwards of the trench (red in Bill's pic).

The more I think about this the more I lean on the side of a regular embedding event. As I pointed out above, the RM trench isn't perfectly smooth. But also, if the RM stalled outright, I might've expected Oppy to yaw around counterclockwise as her right side was slowed by the dead wheel. But there's no sign of that. Also, I might've expected furrows of soil piled up along either side of the RM track, like with Spirit's RF. Again, no clear sign of that.

We'll find out soon enough...

Edit - thanks for the nice illustration, Bill!

Very impressive Bill.

New images down:

http://qt.exploratorium.edu/mars/opportuni...00P1214R0M1.JPG

There's clearly some degree of sinking on the right side as well, so it does look more like a soil composition change rather than a wheel problem on the left side--good news if true!


(Naughty Nprev. Inline image turned into link - ADMIN)

EDIT: Oops, sorry! (Now I finally understand exactly how that works...)

IIRC, when Spirit's RF wheel failed on the way to McCool hill (sol 781) the drive didn't finished immediately but continued enough time to make a long trench.

Now waiting for some official (or "leaked" ) news.

Spirit's right front wheel failed on sol 779, the trench was created following tests to determine the nature of the fault.


http://marsrovers.jpl.nasa.gov/mission/sta...006.html#sol778

I see what appear to be two cleat marks in the image fredk posted, the one nearest the wheel partially buried by soil dropped by the right rear wheel.

Click to view attachment

Discuss...

Soil mechanics experiment to combine with the previous study of driving cross-ripple that they did. That's my guess.

You do the Hokey Cokey...

Yep, Phil, that's what it's all about...

What are you guys referring to? If you mean the little wiggle in the tracks about 1/3 down from the horizon in that navcam image, that's just the small turn in place at the end of the sol 2218 drive:
http://qt.exploratorium.edu/mars/opportuni...0M1.JPG?sol2218

Was this a new trouble free drive then? How far Algernon?

No, just a picture looking backwards taken from the current site.