PMA Actuator problem?, Diagnostics began sol 2257 Options

[Tesheiner]

Notice how the movements are very small, but the az/el positions are very differrent from sol 2259.

Not that different. Here's, for instance, the last shot on 2259 and the first on 2261. I *think* the data on James' two posts used two different reference pointings: rover relative azimuth/heading, and absolute azimuth/heading.

CODE

2259::1P328726956ETHAI00P2864L2M1.IMG::12:29:50::-24.0696::9.7111
2261::1P328904931ERPAI04P2868L2M1.IMG::12:36:19::-24.0682::9.73096

[BrianL]

If the pancam is unusable (and I'm not suggesting that is the case), what would be affected in terms of what the rover can and can't do?

[Phil Stooke]

Assuming it can take pictures but only in a fixed position... the rover can still drive perfectly well, using the fabulous HiRISE images for planning, especially since we are now past the most difficult terrain. At every stop it could do a quarter or half turn, taking several Navcam and Pancam pictures to help with that planning. Only the construction of large panoramas would be prevented.

Phil

[djellison]

Just to correct BrianL's choice of words there - it's not Pancam that's being tested here. Or Navcam even. It's the mechanism that points them. And whatever happens to it, we still have Hazcams.

[fredk]

As Phil said, taking pics separated by drive arcs would presumably be a substitute for a frozen azimuth joint. Pan/navcam are currently looking forwards, so I guess doing drive direction imaging would require some forwards driving at the end of a drive.

If the elevation joint is frozen (and, as you can see, that's a big if), at least it seems to be in a relatively convenient position for drive planning. It would be much harder to compensate for frozen elevation by rover movements where we are now, and probably impossible once we get to the flat tarmac.

[jamescanvin]

I *think* the data on James' two posts used two different reference pointings: rover relative azimuth/heading, and absolute azimuth/heading.

Yes, sorry, I forgot that I had used rover relative last time.

And whatever happens to it, we still have Hazcams.

Of course there is also the slight concern over the RR wheel as well.

[centsworth_II]

It may be a good idea to stop taking 'up' pictures, sun or tau, if there is a possibility of the tilt mechanism sticking. If the actuator fails, they will need to find workarounds anyway. Maybe it would be best to start using the workarounds now. Best to have it stuck in a horizontal position.

[elakdawalla]

Maybe we should wait to learn a little more about the problem and whether it is transient or permanent before we start offering the rover drivers advice, hmmm?

[centsworth_II]

...hmmm?

Hmmm...


I know, I really don't want to be 'that guy'.

[elakdawalla]

I split all the PMA actuator problem posts to this new topic. Original drive east topic remains here.

[Deimos]

If the elevation joint is frozen (and, as you can see, that's a big if), at least it seems to be in a relatively convenient position for drive planning.

The PMA's camera-bar elevation mechanism is completely separate from and less overused than PMA azimuth. But the choice was made long ago that if it were to fail between uses, it should at least fail in a "convenient" position. The end-of-activity stow formerly pointed the cameras straight down. So the cameras are dusty than they'd otherwise be, but are protected against a much worse scenario. [I'm not suggesting an elevation problem, just commenting on the convenience--JPL will release info on the state of the rover when they are ready.]

As for some other posts ... I'll second Doug's point--Pancam is just fine. Not a hint of a problem, it takes pictures and they are posted where all can see. Even if the PMA could not aim it, it is conveniently attached to a mobility system.

As Emily suggests, much needs to be learned before choices are made. Further voluntary restrictions on imaging wouldn't surprise me, neither would a big reduction in Sun images specifically. But no one said up/down is at the crux of the problem. And you also have to weigh what you lose against the risk you face. You do not explore if you are one to just stop activities while paralyzed by fear of something going wrong. Sun images (a small subset of them) let the rover aim the HGA at Earth and currently are needed for long-term mobility (stand on one foot for as long as you can; repeat with your eyes closed; now you know what a rover feels like without checking fine attitude, relying only on gravity). Sun images for tau are less key. But imagine the 2007 dust storm without knowing if it was a failure in the power system. Orbital images would have confirmed the situation eventually, but would leave open a dual-problem path you'd like to rule out. Luckily, dust storms are quite unlikely for a couple months.

[fredk]

Thanks for the insights, Deimos. Thinking about the possibility of losing some functionality has the cool side effect of being reminded of or learning new aspects of how these rovers work, like the solar imaging/HGA connection. These rovers are truly amazing.

[fredk]

Sol 2262 images are down. More hazcam and pancam diagnostics. Pancams show similar small movements in azimuth as we've seen recently, though I can't discern any elevation movements.

Hazcams show no movements in any wheels, for what it's worth.

[Guest_Sunspot_*]

Has one or more of the wheels possibly stopped working too?

[Deimos]

See post #8 for James Canvin's good explanation of the wheel pictures.