There is some slight movement, but enough just to confirm the inability of the motor to move :-(

An animation with the five MI pics taken until now.

Click to view attachment (98k)

I'm not up on lubricants - is the suspected degradation a function of use or age or both? Has Oppy done more IDD work than Spirt, thus putting more "wear" on the lubricant?

I imagine it's much like the Spirit FR wheel issue - just one of those things that happens after some use, but isnt predictable. Unfortunately, there's no 'backwards' to running a joint, so perhaps some higher watermarks for current limits on the motor will help the problem, as perhaps will heating the hell out of it to redistribute grease hopefully (didnt work with Spirit's wheel) , but as with all the actuators and motors on the rovers, they're getting old.

Doug

Playing "what if" with the worst case scenario: if the instrument depolyment arm is permanently stuck, what does that mean for Oppy? First, the mission would continue to operate, for at least as long as Spirit stays largely functional, or as long as the rovers stay mobile, whichever lasts longer. Squires said as much in his interview. For workable instruments, however, they would be down to cameras and Mini-TES.

I wonder what it would mean for power consumption. Do they have a way of killing power to the full arm, and would that be a significant savings when it isn't in use anyway? Suddenly if the Mini-TES is the only instrument besides optical cameras, preserving it from the threat of deep sleep becomes more important, I would think.

I hope our amazingly durable martian friend finds a way to bounce back from this problem, like it has from all others so far!

I guess if we do lose the IDD, it's better to lose it stowed than deployed.

Hmmm...if they can't free the arm with higher motor current limits, could they spin the RAT brushes while stowed to give the IDD some jiggling? Sounds risky, but it might help in a last-resort situation...

Yes, which is another reason why the engineers will be extremely cautious with this problem. You wouldn't want to deploy the arm without knowing whether you will be able to stow it again.

Is it confirmed the fault is not with the protection circuit?

If the rover can be programmed to disregard the fault indication, could it verify the fault is in fact in the deployment motor/gear train?

Doug's suggestion of opening up the current limits is probably safer. If there really is a mechanical problem, you wouldn't want keep running the motor regardless, as it might burn up. It's a tough problem to debug at a considerable distance...

I'm not engineer, but I currently fly remote control aircraft with geared electric motors and in earlier incarnations worked with telescope gear drives. The IDD actuators are likely geared stepping motors and over time the gear train lubricants age and move away from critical points and, well, quit lubricating.

There are four actuators in the arm: a "shoulder joint" which provides left-right motion and near by is another joint which allows the arm to move forward-backward. The arm has two sections and the middle joint is like an elbow and that actuator provides more range of motion. The fourth actuator is like a wrist at the tool carrier and aligns the tool with the surface being thwacked. Of course, a fifth motor rotates the tool holder to select the proper tool.

Of the actuators, I'd figure that the first left-right shoulder joint is least critical and it could be left in one position and hthe arm might be stowed in a non-standard position without it.

I'm sure that there'll be a workaround...

--Bill

Among the remaining possibilities is that, after working more than seven times longer than originally planned, the lubrication is degrading...."

If this is the problem then it certainly didn't occur suddenly. I am forced to wonder if they haven't noticed balky performance of that joint. Have there been current spikes during it's operation? Or can they even track that sort of thing? It would sure help to watch for similar problems on Spirit and other similarly lubricated joints on both rovers.

Something is moving in these two FWD Hazcam frames.

1F186783443ESF64KCP1157L0M1.JPG

1F186783562ESF64KCP1157R0M1.JPG

This looks like a left-right motion to me, which would be produced from the azimuth/shoulder motor - correct?

Are they getting a little motion before the stall now?

Or is that not part of the IDD?

Yeah, something is moving - our point of view. Those are from left and right hazcams :-P
(L in the 4th last letter of the filename tells its the left hazcam, R is right)

[Homer]

D'OH

[/Homer]

I think I'm right in saying that the joint that has the problem (the shoulder) is the one with the stuck heater, right?

This would mean that the joint has had a lot more heating than the one on Spirit and what it was designed for. Could be responsible for possible problems with lubrication or any number of other unforseen things.

Or maybe not, just idle speculation...

James

Long time ago, when Oppy was inspecting inside the Endurance Crater, it had problems with a night with heating switch . It were drawing too much current so it was turned off during night sleeps. So Oppy has spent many days with deep sleeping mode without any heating for IDD.

Then, it might have accelerated the aging process of lubrication parts in joint arms. Otherwise, Spirit has undergone less often as deep sleep than Oppy so Spirit's joint arm is still working and is lasting longer than Oppy.

I am afraid if that problem is due to lack of lubricant on the joint arms. Then, there is no available solution to that unless "someone" is able to fly to where is Oppy to drip some valuable lubricant on the arm joints.

Rodolfo.

"mmmmrrrrllll mmmmcccnnnn."

"What did she say?"

"I think she said 'oil can'!"

Oppy is in a place where she can accumulate rust without ever getting wet...

-the other Doug

Tom Tamlyn , CosmicRocker...looks like our criticism has been noticed by MER site moderators...
Updates are back where they used to be...

Click to view attachment

BTW it's just one more proof that NASA/JPL guys are watching this forum...if someone had any douth...

I have just one more question:
Why are they staying in that one place??? They are unable to unstow IDD arm ( at least for now) so why aren’t they do one thing that they can do with $400M robotic vehicle on Mars…..DRIVE!!!!

Maybe they will find a way to fix this problem once but for now staying in that one place is, despite of that wonderful outcrop , waist of time…isn’t it?

Because they're sat right infront of some fantastic layering which they want to investigate.

Doug

I know that, but consider how many fantastic "rocks","layerings","outcrops" are ahead of us...
There is one only 20-30 meters away...then there is that Victoria crater we all want to see...some of us in this lifetime...
Woud it be souch a terrible los if we skip this one?
Toma B.

It's the same argument that's been had a thousand times. Yes - it's nice to make progress, but yes - one has to take whatever science is infront of you because the rover may not wake up tomorrow.

For all we know - driving might worsen the IDD situation. The IDD may not even be properly parked, and driving could cause irreperable damage.

Yes - it looks like there are some nice outcrops ahead, but we already have one right infront of us - that we are already 'at' and already poised to investigate, with routines for the IDD already written. I can see the case for driving on, but I can see why there
1) may be reasons that we can't drove on
2) are good reasons to stay put till the IDD is fixed, or declared unuseable.

Doug

If you were a geologist, investigating never-before-seen-by-man northern Arizona, would you spend your limited time investigating outcrops near Flagstaff, or would you try to drive your jalopy to the Grand Canyon, even though it may fail on the way? Where would you be more likely to get detailed information on geology from eons past?

Scott

It look as though they're making the most of the pseudo 'down' time anyway - a full 360 Pancam mosaic, and a deck pan. They're already AT new terrain. Yes - it'd be nice to be doing 200m/sol and be at Victoria by Christmas, but sometimes things are just not possible.

Remember - for all we know, the IDD may have moved just enough to be considered un-parked and thus driving CAN'T be done. (infact, I think that's quite likely) - read the updates and it says that it stayed park on the first sol, then the second sol it recorded a small ammount of motion.

To make the anaology more appropriate, would you head out for the grand canyon to do geology without first checking you had your rock hammer and lens in your bag, and that your bag wasnt going to fall off the back of the truck on the way? Oh - and the Truck is parked on top of the first significant layering you've seen in 200 sols... get my point?

Yes - I can see why some would say "get moving" - but I can see why it may not even be possible ( so the argument is mute ) and I can see why they would want to look at what they're parked infront of.

Doug

They have to see if they can get the IDD working at some point. Why would they just completely give up on it without trying all the possibilities? Once they've tried everything they can think of to make the IDD work again, I'm sure they'll move on and do whatever they can (and periodically see if they can get it working again beyond that).

I figured out the real problem. Something is stuck under the arm.

{how'd that get there?}

You win the prize again -- somebody tell Fifth Star or whatever his name was.

IF... big if.. let's hope not... they can't get the arm back in operation, the mission methodology changes to an essentially purely remote sensing operation. They drive to a target and do multispectral images and Mini-TES. Overall travel rate might increase by 50%, and the nature of observation/experiment objectives changes a fair bit.

Suppose the risk of moving the arm and then getting it stuck in a stretched position is so big, management decides to leave it where it is now. Would that actually render the IDD completely useless? Would it still be possible to move the arm in the up/down direction and rotate the instruments head? If so, losing the movement in the x-direction can be compensated for by driving the rover right over the target. Of course this would mean a great limitation in the targets that it can investigate, basically only those that you can roll over are now within reach. But something is better than nothing, as an old Chinese saying goes...

Also, from an engineering point of view, it is very interesting to see how this vehicle slowly degrades. Lessons for next missions (manned and unmanned) can be learned by just watching which components fail and in what order. So, I wouldn't kill the mission too soon but rather stretch it as far as it goes (can talk to us).

Well... Even with no IDD, we have a (i) spacecraft that can move & (ii) able to do a lot of imaging and observations, (iii) with a TES working for which we can still make some kind of rock abrasion with the wheels...
Anyway, better than a Viking Lander !

And really, if the rover becomes a mobile camera platform, well hey, we've got Hubble, whose main mission is simply to take pictures. These things can still do a lot of work, even if it is "just" taking pictures.



Seems like lubrication is a big issue. It nearly paralyzed one of Spirit's wheels, and who knows, it might be an issue with Opportunity. Someone mentioned that 1) Opportunity has endured a lot more cold nights than Spirit due to its deep-sleep mode at night, and 2) it did a lot of IDD work in Endurance. Just during the trip down the slope into the crater, it made a lot of RAT holes.

Weeelll....
Even if they find a way to fix IDD arm I guess it will not be used as much as before...
Maybe they will be gratefull to "Lady Fortuna" that IDD stoped working while stowed because this way they can still do some science with Opportunity...
BTW does anybody knows how much times IDD has been "Stowed-Unstowed"? (100 times or so?)

One solution might be good is that Oppy try to approach to the Mogollon rim where there is somewhat hard wall (aprox 1.6 meter tall). So Oppy must go with its own forward traction and put its arm against the wall and at the same time, turn on the motor to try to retract it.

That is the additional help force from the wheels tractionn to permit in overcoming the initial hardest friction to retract to a safe position before roving. After that, I don't think that IDD might be useful anymore.

The cold weather leads to wear sooner the lubrication. A good leason is to design wheels and movil parts not be so dependent of lubrication by using small diamond balls with some synthetic lubrication that can last thousands kilometers and can tolerate a very low temperature with a very low "W").

Rodolfo

News update:

http://www.jpl.nasa.gov/missions/mer/daily.cfm#Opportunity

--Bill


Latest Opportunity Update
Stalled Motor, Stowed Arm
Opportunity Status for sol 649-660
Release Date: 12/1/05

Opportunity drove 43 meters on sol 649 (Nov. 20, 2005) and then bumped 10 meters to an outcrop for work with its robotic arm (instrument deployment device) over the Thanksgiving holidays. Opportunity's commands for sol 654 (Nov. 25, 2005) included unstowing the arm to begin using the tools on it for examining the layered outcrop that the rover had driven to three sols earlier. The arm is always stowed during drives. This time, a shoulder-joint motor that is needed for unstowing the arm stalled, and the arm stayed stowed. In subsequent sols, engineers worked to narrow the range of possibilities for the cause of the stall. Among the remaining possibilities is that, after working more than seven times longer than originally planned, the lubrication is degrading. One possible fix would be to increase the duration of the allowed motor start-up, to overcome the increased initial friction. The first diagnostic activity for the arm was performed sol 659, where a very small motion was recorded. Future diagnostic activities and continuing analysis will be performed to further characterize the shoulder-joint motor in upcoming sols.

As of sol 659 (Nov. 30, 2005), Opportunity has driven 6,502 meters (4.04 miles).

Bill: Note Toma's post (#46)

http://www.unmannedspaceflight.com/index.p...indpost&p=29540

Hi Guys
I don't know if it's just a coincidence but the last time both rovers successfully used their microscopic imagers was on the same day 26th November(at least that is when images came down on exploratorium)
maybe some new stowing sequence delivered to both rovers about that date could have caused the problem?
Any ideas?

Reckless

An MI healthcheck image has been scheduled for Spirit on the pancam traking site for a couple of sols - so I wouldnt read anything into it - I think it might well be a comparison image to go "right,we know spirit's IDD is parked, what does the IDD show there....now what does the oppy image look like...." as a secondary visual gauge of the IDD's exact position - probably down to a sub millimeter accuracy I would imagine. Then - they'll be able to either

a) Set off in the knowledge that the IDD is properly parked and work on the issue while coveirng ground

or

Know they need to fix the issue right now as it isnt parked and thus they cant drive

Comparing the two
http://qt.exploratorium.edu/mars/spirit/mi...W6P2900M1M1.JPG
http://qt.exploratorium.edu/mars/opportuni...KCP2900M1M1.JPG

It's clear that Oppy's IDD isnt parked in the same position as Spirit's - and thus it may be that it's not parked at all, or it's parked 'enough' to allow driving

That's my take on it all anyway.
Doug

The difference between two pictures, the ones of Spirit, the background image is, I seems, of surface land (stones on the mountain) and the ones of Oppy is on the sky (around Oppy has no high lands) but I am not sure of this. It is because, the upper of image there is a shadow line, I am not able to figure out of this. The center stick is of the arm. I seems that the Spirit's arm has a semi-wear scotch. The Oppy case has no scotch sticking on the arm.

Rodolfo

I haven't heard anything since Friday, but here's an update based on some inside information.

1. Opportunity's IDD is in a halfway-unstowed configuration. The arm unstows in four moves. The first move (apparently completed) raises the elbow toward the roof above it, in order to release a hook. The second move (not completed) is a joint 1 (azimuth) move that results in the elbow end moving forward, while the turret disengages its stow feature. The third and fourth moves get the arm in a neutral pose in front of the rover.

2. The arm itself doesn't appear to be mechanically hung up at either the elbow or the turret. The problem is in the motor of joint 1, which turns slightly, but stalls before even one motor revolution is completed. (The motor is a DC brush motor with magnetic detents. It fails to get out of the first detent.)

3. The team is experimenting daily on the arm, starting with parameter changes like
"stall persistence" (how quickly the circuitry shuts down the motor). They have not yet upped the current to the motor, but that should come soon. So far, the symptoms do not have an easy explanation.

In the worst case, if joint 1 can't be budged, the arm can be restowed because that action does not involve joint 1. In the meantime, I don't think the arm is in a configuration which is "officially" safe to drive. I also don't think they can easily experiment on joint 1 when the arm is stowed. So you may as well get used to this spot for a little while longer.

Nice update mars_armer. Mixed news but it's nice to see that the team are being thorough.

Patience is in order folks. I quite like the view to be honest, she could have been stuck in far less interesting spots.

Ditto what Helvick said. Oppy is doing a LOT of nice Pancams of wonderful subjects.

--Bill

Oh well............. at least we have something interesting to look at this time.

More news today, and it's not too bad. A likely explanation for the problem is that one of the two motor windings is open (possibly the stuck open heater is a partial cause for this). It's not inconceivable that the motor could be operated on just one winding, so don't give up yet.

Why would they need to use Spirit as a reference? They have the engineering units on the ground for that.

ed

The engineering units haven't been working in a Martian environment for over a year.

So, Oppy's endgame begins to play out... It's obvious that her IDD, if it can be made to work again, only has so many deploys left in it.

As Steve Squyres said in one of his many public speeches since the MERs landed, near the beginning of the mission, they would "whip out the arm" any time they got close to anything that looked even remotely interesting. But now that the rovers are getting older, the MER team is getting more cautious using things like the IDD, which could wear out and stop working at any time.

The arm can only be deployed a relatively few more times. The question now becomes, when and where?

I think the MER team needs to make some hard decisions. Do we continue to work up the interesting bedding and mineralogical differences we're seeing at the Erebus rim, or is there enough more to be gained by arriving at a locale like Victoria with a functioning IDD that would justify the risk of a mad sprint?

It would be very, very hard to sprint through the expanse of sporadically exposed bedrock that lies between us and Victoria without giving in to temptation and stopping to investigate. But, but, but -- can we deploy the arm 20 more times? Ten? Five? Two?

We just don't know. And we probably *won't* know until we rudely discover that the remaining number is zero.

IDD deploys may have just become the coin of the realm at Meridiani. Let's hope (and trust in a bit of luck) that we can spend it wisely.

-the other Doug

Maybe they should save it for Victoria, if we ever get that far....

Question:
What would happen if the IDD arm was fully unstowed when brakedown occurs...
Could Opportunity drive backwards dragging it behind him?