Post Solar Conjunction/Santorini Study Drive, The second leg in our Journey to Endeavor Crater Options

[James Sorenson]

I was just looking over the tau images on Sol-1797 on Opportunity, and I found somthing pretty odd. At first look I thought maybe it is just a cosmic ray hit or just random noise, but when put into into a gif, it looks to be somthing different. Any ideas?

[Floyd]

Thanks for the answer Paolo! We will all hold good thoughts that the RF wheel current returns to normal.

[stevesliva]

. At first look I thought maybe it is just a cosmic ray hit or just random noise, but when put into into a gif, it looks to be somthing different. Any ideas?

Are they hot pixels? There are two that move in formation. Or I should say, the sun is moving, and the pixels are stationary in formation...

[James Sorenson]

I'm sort of now thinking that .

[dvandorn]

Um, yeah -- I mean, it's either hot pixels or you've caught the Barsoom Airlines flight pattern out of Helium, all the commuter aircraft bound for the great thoat roundup...

-the other Doug

[Stu]

A couple of new 3D images on my ROAD TO ENDEAVOUR blog if anyone wants a look...

http://roadtoendeavour.wordpress.com/2009/...dows-and-tracks

[Tesheiner]

... On 1800 we drove backwards that in the past help redistribute the lubricant, then drove forwards the same way we drove on 1797 and we'll see what the wheel currents look like. At the end of the drive we also did a few steps in a way they match the natural curvature of the RF wheel as another test to see if the currents are back to normal.

Today's (sol 1802) imaging plan has only a tau measurement.

[RoverDriver]

Today's (sol 1802) imaging plan has only a tau measurement.

This was a long weekend (president's day holiday). The Sol 1800 currents were still high, today it will be one more diagnostic test I believe.

Paolo

[Tesheiner]

Oops, I wasn't aware of the holidays.
With the low activity today (in terms of MB) I hope those images looking toward Endeavour get a chance on the downlink queue.

[BrianL]

Well, if we are heading toward a wheel lockup, I think it's time to tell Oppy, no more bathroom breaks till we reach the parking lot terrain.

Paolo, any plans to experiment with that wheel held locked just to see how well she moves through the ripples? If it is not too big an impediment to travel, could locking up the wheel actually extend its lifespan for situations where all 6 wheels are really needed?

[RoverDriver]

Well, if we are heading toward a wheel lockup, I think it's time to tell Oppy, no more bathroom breaks till we reach the parking lot terrain.

That's why she ended up with one wheel locked toed-in, she was trying to hold it ;-)

Paolo, any plans to experiment with that wheel held locked just to see how well she moves through the ripples? If it is not too big an impediment to travel, could locking up the wheel actually extend its lifespan for situations where all 6 wheels are really needed?

I have no idea (and probably the rest of the team as well) whether this is a symptom of actuator wear. W know that backwar driving reduces the current a little, so we might decide to drive backwars for a while. That is mutually exclusive with Autonav/D* tho.

Regarding extending the lifespan of the wheel y not using it: when I moved to the US a long time ago I bright with me a PAL VCR. It was well used when I moved, and it arrived in perfect shape. I used it every once in a while to watch tome PAL tapes. Then I decided to use it sparingly. In about three months of being unused the drum stopped spinning freely (due to lubricant breakdown).

So if they will ask my vote, I will vote to continue using the actuator for as long as we can. There's always time to test whether we can cross ripples when the wheel stops working :-(

Paolo

[Geert]

I have no idea (and probably the rest of the team as well) whether this is a symptom of actuator wear. W know that backwar driving reduces the current a little, so we might decide to drive backwars for a while. That is mutually exclusive with Autonav/D* tho.

How much is influence of the sand is driving through? Quite recently she moved from bedrock to more sandy areas, and it seems to me the front wheels take the brunt from this they 'dig the track' that the other wheels are following in. A bit further on she will be back on bedrock patches, so hopefully this will help.

Regards,

Geert.

[RoverDriver]

That is my personal take (that the higher wheel currents are due to the soil type), but I have to be honest and say that the increase is quite a bit larger than we have experienced so far. We did see higher wheel currents on the RF prior to VC, on the north side of VC and in the "parking lot" south of VC, but the difference between the RF wheel drive current and all other wheels was small compared to what I see now. So at this point my *hope* is that this is due to the soil.

Paolo

[Geert]

I think we all share this hope with you, lots of positive waves must help

Looking at the rear hazam images on sol 1800 and 1797 it looks a bit like the right wheel was digging deeper into the soil then the left wheels. The driving she is doing now is different from driving on 'parking lot' soil, when she is driving south in between the dunes there are often situations where one side is more or less 'on' (or 'in') a ripple while the other side is in a through, it stands to reason that in such a situation drive currents will be higher on the side which has to dig deeper through the soil. On previous 'parking lot' trips all wheels were on equal footage and that would make a lot of difference.

On Spirit I'm always amazed that the 'stuck' wheel is really 'stuck', it is not turning at all, normally with a burnt electro motor you would expect that you could still turn it (even though it would show some resistance), but it looks like the wheel is full on the break, everything would be a lot easier if it would turn at least a bit...

Regards,

Geert.

[Nirgal]

Probably I'm missing something but if I remember correctly then wasn't Oppy used to regularly alternate between forward and backward driving for better "wear distribution" anyway ?
Or has it something to do with the stuck IDD or the new flight software that could make regular backward-driving more difficult ... ?