[X] My Assistant

[RNeuhaus]

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

[mars_armer]

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.

[helvick]

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.

[Bill Harris]

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

--Bill

[Guest_Sunspot_*]

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.

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

[mars_armer]

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.

[Guest_Edward Schmitz_*]

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

ed

[Jeff7]

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

[dvandorn]

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

[Toma B]

...The question now becomes, when and where?

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?

[Guest_Sunspot_*]

http://www.pasadenastarnews.com/news/ci_3282301

"It's already been used more than almost seven times it's design life," Lindenfeld said. Still, he said, with JPL's track record of fixing spacecraft anomalies, he said he has a feeling this will be the end of the show for the robotic arm.

[Tesheiner]

http://www.pasadenastarnews.com/news/ci_3282301

Thanks for the link, Sunspot.

I would like to remark the following sentence:

Callas said if the anomaly team determines that the problem cannot be repaired and the rover is on its last legs, the goal will be to get the shoulder to move one more time so it ends up in an extended position. That way it would still be able to use the scientific instruments, only with a loss of some flexibility.

[djellison]

It's moved ever so slightly..


http://qt.exploratorium.edu/mars/opportuni...KCP2900M1M1.JPG

http://qt.exploratorium.edu/mars/opportuni...KCP2900M1M1.JPG

Doug

[dot.dk]

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.

What do you mean when you say it is "open"?

And why would the heater be responsible for this?

[Bill Harris]

> one of the two motor windings is open (possibly the stuck open heater is a partial cause for this).

I'm not trying to second-guess mars_armer, but I'd suppose that, since it is a brushed motor, one pair of the brushes is not making good contact with the commutator. Since the heater had stuck open and they had to disabel it, this problem may be cold related.

--Bill