SUPRISE......New Steve Q'n'A, Recorded Nov 6th 2006 Options

[djellison]

Everyone likes suprises right....

At very short notice ( <36hrs ) - Steve and I managed to meet up in Milton Keynes yesterday evening and do another Q'n'A - this time an hour long talking about everything that's gone on in the last 12 months or so since the first Q'n'A last September.

http://www.rlproject.com/audio/ss_qna_071106.mp3
Approx 14 Meg, 1 hour 48 seconds long.

Sorry I didn't have time to do a call for questions - but with the time between knowing it was on and doing it being so short there just wasn't the time to call for them, plough through them and then pick them...I think I got through all the good stuff though. I tried to see any left over stuff mentioned here, things that might have been asked for a Pancam update but better suited to Steve rather than Jim - and I was able to ask my admin team if they could think of any as well ( thanks guys ).

This time it was on the lounge area on a hotel landing....no ducks or wind noise - but occasional passers by heading to and from their hotel rooms - I hope the quality's good enough (I think it is)

If someone wants to put down time markers for transcription and people do the same as last time, I'd be happy to put together another PDF like last time.

Enjoy!

Doug

[odave]

Section 3 (minus NMRguy's overlap at the beginning )
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DE: [laughs] let's get out the medical record...

SS: Alright. So, on Spirit you already hit the high points. The right front wheel doesn't turn anymore, the RAT is worn out, though of course we can brush, we did get some dust on the MiniTES mirror because we were taking a MiniTES observation when we got hit by one of our wind gusts, and the very same gust that cleaned off the solar arrays deposited some dust on the mirror.

DE: Can you subtract out the dust?

SS: Yeah, the MiniTES guys have developed a technique for removing the affects of that so that's not a big detriment to the science. Let's see, what else on Spirit. Um, nothin' mechanical, nothin' electrical...other than that, Spirit's in really good shape. On both vehicles we've had some deposition of dust from time to time on the Hazcam optics. I mean, you've seen that in some of the images. When you take big camera lenses and you put 'em close to ground level in a windy place you're gonna get a little dirt. But nothin' too bad there. Let's see, on Opportunity. Of course you know the right front steering actuator doesn't work any more, and that affects our ability to steer a little bit, though we've gotten - that's been going on for so long we've really, we've completely learned how to compensate for that.

The one that makes me lose the most sleep is that we've got that broken wire in joint 1, the azimuth joint on the IDD, the arm. It causes us problems from time to time. That joint, when you use it, 95+ percent of the time it works just fine and a few percent of the time, you send a command to it, it doesn't move properly. And what it tends to be most often is small moves, like the kind of things you would do in an MI mosaic. So we try to use that arm carefully because when the thing stalls on ya, it takes a couple of days, couple sols to recover from it, which is kind of a pain in the neck. And the thing that is scariest about that issue is not that occasionally it inconveniences us, that we can deal with, but that it's one more broken wire away from losing that joint completely. And that's the reason we keep the arm out, of course, most of the time now, is because if we fail, if we were to fail stowed, then you'll never be able to use the arm again. Whereas if you fail deployed, you've got a four degree of freedom arm, you just can't move the shoulder back and forth.

Let's see, what else is wrong on Opportunity? Well, of course the Opportunity MiniTES just totally freaked out on us for a while and was returning bad data. We think that we broke it by taking it to extremely cold temperatures at night as a consequence of doing the deep sleep that we need to do with that vehicle. But then it healed itself, and I can't explain that.

DE: That just makes no sense...

SS: I have no idea how that happened. It's just so typical of the way things have gone on this mission. But yeah, MiniTES healed itself and MiniTES has been totally fine for a very long time now. There's one thing that's a little weird on Opportunity where on a number of occasions we have sent commands to the Microscopic Imager to acquire an image and the commands were rejected as being invalid. And what that means is some bits got flipped as the command was being transmitted from the CPU to the camera. The way the flight software works, if that happens to a camera, the first thing it tries to do is re-transmit it one more time. And every instance, I believe, there might have been one or two where this wasn't true, but in virtually every instance where that's been the case, when we had a rejected command, when it was sent the second time, it worked. What we think this might point to, and this is pure speculation, is that there might be some degradation of the cable. There's what's called a flex print cable, which is what's used to send a lot of signals up and down that arm. It's a very complex cable because it's gotta go through all these joints...

DE: ...all the joints...

SS: ...and everything, yeah, and with lots of motion and lots of wear,

DE: a lot of temperature swings...

SS: Yeah, lots of thermal cycling. With all of that, the cable can begin to degrade a little bit, and if you have some wear of the cable, you could wind up starting to get a little cross-talk between adjacent wires or something like that and have corrupt signals going up and down the arm. But we've seen very little of that, and it doesn't seem to be getting worse. Let's see...oh yeah, and then we have an intermittent problem with the internal reference channel on the Opportunity Mossbauer Spectrometer. It's got the four main detectors at the front end of the instrument which are used to collect the science data, and on the back end of the instrument there's a fifth detector that is used for calibration. And we've been having intermittent problems with that reference channel. It's not causing us any difficulties because A] it works some of the time, and B] even if we lost it entirely, we have a completely separate Mossbauer calibration target that's mounted on the rover that we can look at externally if we need to. So either way, we've got that covered. And I think that is everything I can think of that's wrong with both vehicles right now. Plus they're dirty [laughs].

DE: A bit of dirt...