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Unmanned Spaceflight.com > Mars & Missions > MER > Opportunity
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SFJCody
Uh oh.

https://qt.exploratorium.edu/mars/opportuni...W6P1211L0M1.JPG

Time to put it in reverse and floor it!

Edit:

... what happened here?

https://qt.exploratorium.edu/mars/opportuni...W6P1311R0M1.JPG
remcook
...ehm...testing the consistency of the soil? (which looks...interesting)

Hope it's not actually dug in in a way that it can't move.
Geert
QUOTE (SFJCody @ Apr 23 2009, 08:46 PM) *
... what happened here?


Looks a bit like she started sliding sideways off a dunetop, maybe at the same time the front wheels dug in?

Definitely doesn't look good.

What's her position, is this at the end of the 1864 drive or has she been driving since?
Tesheiner
Today (1865) was driving sol too and the mobility info tells the rover moved 90+ meters.
I'm pretty sure this, mmm, "event" happened while Opportunity was driving in "blind mode" so that 90m figure is not really correct. Some of those 90m (10, 20, 30?) were actually slipping the wheels in the drift.
I'll wait for additional navcams to try plotting an accurate new position on the map.
SFJCody
Maybe she tried to do a turn to set up for a switch to reverse driving the next sol and ran into a nasty ripple. Looking at Geert's driving hazard map, I think there's a good chance she's in one of the red patches.
Tesheiner
Actually, the tracks seen in the RHAZ images resemble a CCW turn.
Poolio
QUOTE (Geert @ Apr 23 2009, 10:37 AM) *
Looks a bit like she started sliding sideways off a dunetop, maybe at the same time the front wheels dug in?

Wouldn't we see some evidence of the front wheels having twisted in place in this were the case? It looks like the front wheels drove straight in and got stuck.

Something else that's bugging me: I don't actually see any ripples or dunes in the front hazcams. Is the immediate foreground as uniform as it looks, or are the dunes just too hard to make out from the low angle?
AndyG
We shan't notice that it's nearly the fourth Earthanniversary of being stuck at Purgatory.

Four years! Crikey.

Andy
Geert
QUOTE (SFJCody @ Apr 23 2009, 10:47 PM) *
Maybe she tried to do a turn to set up for a switch to reverse driving the next sol and ran into a nasty ripple.


That was my original thought as well, but this looks like a shallow turn, not the type of about-turn you can expect for a comm-session or a reverse drive. Maybe she was switching to autodrive and the software sensed something wrong and turned to the right, it looks to me a bit like the type of turn you can expect from auto driving mode. The frontwheels are hardly turned at all as if she ran streight into the dune.

Front doesn't look too bad, but those rearwheels are a mess...
SFJCody
QUOTE (Geert @ Apr 23 2009, 04:09 PM) *
Maybe she was switching to autodrive and the software sensed something wrong and turned to the right


Sounds likely. Maybe the path straight ahead was also a bit of a dust trap, so the software detected excess slip, backed out and tried to avoid it only to get stuck somewhere else. The multiple sets of tracks might have been caused by this happening multiple times.
Tesheiner
Here's my first attempt to locate our current position.
Click to view attachment

> Maybe the path straight ahead was also a bit of a dust trap, so the software detected excess slip, backed out and tried to avoid it only to get stuck somewhere else.

AFAIK, if excessive slip is detected the rover just stops. It doesn't autonomously attempt another move.
Geert
I'm still trying to make sense of the track of that left aft wheel, but I can't figure out what happened, like it just completely slipped sideways..

(wisper mode) I sure hope that the RF wheel hasn't given out, that would explain the sudden turn to the right and the deep dig on the right aft... unsure.gif
alan
I think the left front wheel stopped making forward progress and the other wheels pivoted around it because the right side continued to move forward. Maybe someone with a model and some flour could try a simulation.
ustrax
sad.gif

Tesheiner, can you now tell with more accuracy, since you have pinpointed Oppy's position, how much of those 90+ meters were made slipping?

The Porcupine incident will be one more story, and a valuable lesson, to remember in the years to come...Oppy will get out of it! smile.gif
Tesheiner
Just a few meters, I would say.

> Oppy will get out of it!

No doubt at all!
Geert
QUOTE (ustrax @ Apr 24 2009, 12:24 AM) *
Oppy will get out of it! smile.gif


I'm sure she will get out of it, I was looking back at the purgatory front and hazcam pics and then the wheels were FAR deeper down then they are now. It's more a 'what happened' situation, but that will get clear once they take more pancam and navcam shots.

This will just give the RF wheel some more rest, give the lubricant time to settle again..
alan
Tesheiner, I think I would put the red dot back a bit, about where the yellow line crossed the black arc you drew. That would put the left front wheel in the biggest dune on the path you drew.
imipak
ISTR Steve Squyres, when Endurance was announced as the next destination, saying that we'd see more embedding incidents along the way. I'm puzzled by the appearance of (???) three wheel tracks almost side-by-side, though.
Stu
Quite a trench you've dug yourself there, Oppy... you get jealous of Spirit's trenching?

Click to view attachment
SFJCody
Trenching? What Oppy's been doing there looks more like ploughing!
fredk
To much action on this thread all of a sudden to keep up! I had made this sketch, and then read Alan's comment above. It seems we agree on this refinement to Tesheiner's location:
Click to view attachment
It looks like we had been driving more or less southwards (cyan line), made a bit of a turn to the west to avoid a big dune, but still managed to get our left front wheel stuck in the dune (cyan circle). The right centre and rear wheels then pivoted around to the right, giving the wide spread out tracks, as people have pointed out already.

Looking in the rear hazcam, it appears we're actually very close to the bedrock patch you outlined in black, Tesheiner. So this should be very easy to extract from: just back up with perhaps a turn towards the west, which will take us down off the dune and onto the bedrock.

PS - have people noticed how close we are keeping to the projected route in this official route map? In fact, that route has us on the bedrock just a bit to the west of the dune we're now stuck in...
Tesheiner
QUOTE (alan @ Apr 23 2009, 06:34 PM) *
Tesheiner, I think I would put the red dot back a bit, about where the yellow line crossed the black arc you drew. That would put the left front wheel in the biggest dune on the path you drew.

Oh. The "route" is the one derived from the mobility data, assuming no slip. The real position is actually a few (?) meters before, more or less where you say.

The scenario proposed by Fredk seems to be closer to reality then mine.
Poolio
QUOTE (fredk @ Apr 23 2009, 01:23 PM) *
made a bit of a turn to the west to avoid a big dune

This implies that the blind portion of the drive had completed and that the rover was in autonav. If so, that's good news. If the rover stops to assess its surroundings every 3 meters (I think I've read that somewhere) then there shouldn't be more than a few meters of spinning that went in burying those wheels. Compared to Purgatory, which was about 22.5 meters worth of spinning. This is encouraging.
Tesheiner
Here's another snapshot from Google Mars with today's path as reported by the rover itself.
The "blind drive" is the first diagonal segment and the next 20m southwards; the remaining part was "autonav" (I suppose). There are slight discrepances with the "ground truth" but it gives an idea of the commanded drive.
Click to view attachment
SFJCody
Let's hope what they have scheduled works!
QUOTE
Sol Seq.Ver ETH ESF EDN EFF ERP Tot Description
----- -------- --- --- --- --- --- ---- -----------
01866 p1201.07 0 0 0 0 0 0 front_haz_penultimate_1bpp_pri17
01866 p1201.07 0 0 0 0 0 0 front_haz_penultimate_1bpp_pri17
01866 p1201.07 0 0 0 0 0 0 front_haz_penultimate_1bpp_pri17
01866 p1201.07 0 0 0 0 0 0 front_haz_penultimate_1bpp_pri17
01866 p1211.03 0 0 0 0 0 0 ultimate_front_haz_1_bpp_pri_15
01866 p1211.03 0 0 0 0 0 0 ultimate_front_haz_1_bpp_pri_15
01866 p1254.02 0 0 0 0 0 0 front_haz_fault_pri15_4bpp
01866 p1301.06 0 0 0 0 0 0 rear_haz_penultimate_1bpp_pri17
01866 p1301.06 0 0 0 0 0 0 rear_haz_penultimate_1bpp_pri17
01866 p1301.06 0 0 0 0 0 0 rear_haz_penultimate_1bpp_pri17
01866 p1301.06 0 0 0 0 0 0 rear_haz_penultimate_1bpp_pri17
01866 p1311.07 0 0 0 0 0 0 rear_haz_ultimate_1_bpp_crit15
01866 p1311.07 0 0 0 0 0 0 rear_haz_ultimate_1_bpp_crit15
01866 p1354.01 0 0 0 0 0 0 rear_haz_fault_pri15_4bpp
01866 p1981.26 0 0 0 0 0 0 nav_2x1_rvraz_0_1_bpp_pri24
01866 p1981.26 0 0 0 0 0 0 nav_2x1_rvraz_0_1_bpp_pri24
01866 p2601.03 0 0 0 0 0 0 pancam_tau_L78R48
01866 Total 0 0 0 0 0 0

Tesheiner
I think I pinpointed the current position. Here it is, together with an updated path for this unlucky drive.
The last part of the path (backwards segment) represents the distance Opportunity was moving the wheels but stuck in the sand.
Click to view attachment

> Let's hope what they have scheduled works!

One mars bar that the rover is extracted in the first attempt! smile.gif
Astro0
The wheels don't look in that bad a position in these gamma adjusted images.
Click to view attachmentClick to view attachment
Animation

At least the view is nice wink.gif
Click to view attachment
CosmicRocker
QUOTE (Tesheiner @ Apr 23 2009, 03:06 PM) *
... One mars bar that the rover is extracted in the first attempt! smile.gif
I agree, Eduardo.

In fact, it should be pointed out that if Oppy does back out on the first attempt, she was not stuck in the first place! cool.gif
ustrax
QUOTE (Astro0 @ Apr 24 2009, 01:48 AM) *
At least the view is nice wink.gif


Yes it is...Is that Endeavour or some other crater on the horizon?
jamescanvin
Looks like Endeavour to me.

I agree with others here -It doesn't look that bad, we'll be out of here in no time. smile.gif
Tesheiner
What about a name for this place. "Porcupine trap"? ph34r.gif
djellison
'The Spines'
climber
I agree it doesn't look too bad, and that's the most important. Nevertheless, regarding what "they'll" do next, I can see 2 solutions:
1- analysis shows that Oppy's software reacted as advertised and this could lead to drive very soon and even more agressively.
2- the reaction is not understood enough or not appropriate and we could stay there for a while.
When next drive will occur, that'll tell us something either way.
wheel.gif
djellison
Next drive is already scheduled for today.
paxdan
QUOTE (djellison @ Apr 24 2009, 09:15 AM) *
'The Spines'

parkupine
djellison
That's only fair if we don't get out in a Sol smile.gif

But I like it biggrin.gif
Stu
QUOTE (paxdan @ Apr 24 2009, 11:02 AM) *
parkupine


Genius, sir. smile.gif
centsworth_II
QUOTE (djellison @ Apr 24 2009, 03:15 AM) *
'The Spines'

Careful... you'll get stuck.
SFJCody
Well, the images are down (for Spirit as well), but exploratorium is playing up again! mad.gif
Tesheiner
The mobility data tells that Opportunity actually moved back 30cm; slip rate 40%.
I believe those are good news. smile.gif
Poolio
So that means the commanded drive was for 1/2 meter? I'd say that's excellent news.
Tesheiner
> So that means the commanded drive was for 1/2 meter?

IMO, yes.
RoverDriver
QUOTE (Tesheiner @ Apr 24 2009, 11:41 AM) *
> So that means the commanded drive was for 1/2 meter?

IMO, yes.


The commanded drive was much longer (5+5m) but as a precaution we have an average current limit checking that was tripped during the first 50cm step. The good news is that the single step we executed had good slip values and the cleats are clean. The bad news is that we executed only (part of) one step.

I am quite surprised by the title of the thread. I was expecting better from you guys! This one does not look as bad as "Spears Ripple" (833) or the 603 drive. "Parkupine"! Tsk!

Paolo
PS: just to make sure nobody gets upset, my comments are ironic! smile.gif smile.gif smile.gif smile.gif
SFJCody
QUOTE (RoverDriver @ Apr 24 2009, 07:54 PM) *
The commanded drive was much longer (5+5m) but as a precaution we have an average current limit checking that was tripped during the first 50cm step. The good news is that the single step we executed had good slip values and the cleats are clean. The bad news is that we executed only (part of) one step.


I guess that would explain why not all the requested hazcam pairs came down.

QUOTE
Sol Seq.Ver ETH ESF EDN EFF ERP Tot Description
----- -------- --- --- --- --- --- ---- -----------
01866 p1201.07 0 0 0 0 0 0 front_haz_penultimate_1bpp_pri17
01866 p1201.07 2 0 0 2 0 4 front_haz_penultimate_1bpp_pri17
01866 p1201.07 0 0 0 0 0 0 front_haz_penultimate_1bpp_pri17
01866 p1201.07 2 0 0 2 0 4 front_haz_penultimate_1bpp_pri17
01866 p1211.03 0 0 0 0 0 0 ultimate_front_haz_1_bpp_pri_15
01866 p1211.03 2 0 0 2 0 4 ultimate_front_haz_1_bpp_pri_15
01866 p1254.02 0 0 0 0 0 0 front_haz_fault_pri15_4bpp
01866 p1254.02 0 0 0 0 0 0 front_haz_fault_pri15_4bpp
01866 p1301.06 2 0 0 2 0 4 rear_haz_penultimate_1bpp_pri17
01866 p1301.06 2 0 0 2 0 4 rear_haz_penultimate_1bpp_pri17
01866 p1301.06 0 0 0 0 0 0 rear_haz_penultimate_1bpp_pri17
01866 p1301.06 0 0 0 0 0 0 rear_haz_penultimate_1bpp_pri17
01866 p1311.07 2 0 0 2 0 4 rear_haz_ultimate_1_bpp_crit15
01866 p1311.07 0 0 0 0 0 0 rear_haz_ultimate_1_bpp_crit15
01866 p1354.01 0 0 0 0 0 0 rear_haz_fault_pri15_4bpp
01866 p1354.01 0 0 0 0 0 0 rear_haz_fault_pri15_4bpp

Juramike
QUOTE (RoverDriver @ Apr 24 2009, 02:54 PM) *
PS: just to make sure nobody gets upset, my comments are ironic!


Ahhh, but the sands are ferric.

smile.gif
Tesheiner
QUOTE (RoverDriver @ Apr 24 2009, 08:54 PM) *
I am quite surprised by the title of the thread.


That was my fault. (English isn't my mother language) wink.gif
And now looking to the FHAZ images, the "trench" is really minimal. Perhaps we should rename the thread as "(Almost) stuck near Porcupine" or "Pit stop near Porcupine". smile.gif

Now, going back to the first posts in the thread. At that point in time, with no available data except for the end of drive pictures, I was convinced the "incident" happened during the blind part of the drive. Later on I realized it was during the autonav part. I always thought the latter had "slip-check" (visodom?) enabled so such kind of excessive slippage would be immediately detected. Is that true?
SFJCody
Looks like exploratorium is back.

pancam.gif http://qt.exploratorium.edu/mars/opportuni...W6P2439L6M3.JPG

What a view!
RoverDriver
QUOTE (Tesheiner @ Apr 24 2009, 01:19 PM) *
That was my fault. (English isn't my mother language) wink.gif
And now looking to the FHAZ images, the "trench" is really minimal. Perhaps we should rename the thread as "(Almost) stuck near Porcupine" or "Pit stop near Porcupine". smile.gif

Now, going back to the first posts in the thread. At that point in time, with no available data except for the end of drive pictures, I was convinced the "incident" happened during the blind part of the drive. Later on I realized it was during the autonav part. I always thought the latter had "slip-check" (visodom?) enabled so such kind of excessive slippage would be immediately detected. Is that true?


Eduardo, English is not my primary language either, and I did not mean to criticize. It was really meant as a joke.

Slip checks are called typically every 10-20m, not at every step. Each slip check takes 5-12min, that's why we do not do that more often. We have determined that even if we have an embedding event whiel commanding 20m this should result in a situation that we should be able to resolve in a sol or two. This has been determined to be an acceptable risk. We do slip checks both during the blind (both forwards and backwards) and the autonav portion of the drive (forwards only).

This embedding evend does not surprise me. The lee side of the ripples are covered by a soft, cohesionless fine powder, while the opposite side is more compact and results in better traction. Autonav tried to avoid the ripple since it had a slope that was considered too high. The avoidance resulted into an arc that was sufficient to clear the ripple crest, but not the "fluffy stuff" (techincal term that drivers use to call this type of terrain).

So, IMHO, this is something that from time to time will happen, we have means to mitigat the effects and we know how to deal with the consequences.

Paolo
helvick
To be honest I think the whole event shows just how awesome the driving techniques are.

HughFromAlice
Yes - awesome is the right word!!
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