The West Valley Route Options

[marsophile]

... I'm thinking that it's sort of like a very deep trench in an ocean floor; a sort of -- oh, what's the word? It's on the tip of my tongue...

Mariana Trench? That seems like a good name.

[Guest_Sunspot_*]

This is extraordinary news.... its such a shame they are having some mobility problems in the soft soil at the moment.

[dvandorn]

Mariana Trench? That seems like a good name.

I think he was going for an abyssal plain, something like that...

-the other Doug

[Fran Ontanaya]

A bright sun falling on her, stuck in white sand, a strange behaviour... she's like Jack Sparrow at the World's End.

Now she only needs an army of stone crabs to get her out of there.

[Tesheiner]

Unbelievable numbers!
So now we know where she should go when the power levels become too low. Perhaps in one mars year time, after the campaing at VB&G is finished and after enduring yet another winter somewhere nearby, she should return here to get some "cleaning" once again.

[dvandorn]

My concern is that we may not get a chance to see Spirit come back to this place... as in you can't come back to a place you're unable to leave...

-the other Doug

[serpens]

you can't come back to a place you're unable to leave...

Oh ye of little faith. She is backing out. Slowly but surely. But if there is no passable route to VB for a crippled rover then then she will be all powered up with nowhere to go.

[climber]

So now we know where she should go when the power levels become too low. Perhaps in one mars year time, after the campaing at VB&G is finished and after enduring yet another winter somewhere nearby, she should return here to get some "cleaning" once again.

I don't think we'll need to.
Now we know that we have to winter with an angle and that we have to get a place for clean up around the solstice. My choice for next solstice will be to get in between Goddard and VB (IF we can climb there) where the ridges physionomy are very much the same as where we are: a kind of col (path).
Now I'm wondering if the place where we are stucked (not for long I believe ) is due to a material accumulation by the wind for the same reason this location is a cleaning place. If this is the case we have to know where the wind come from since the material can accumulate before the col or after... or both... which in this case will mean more sand traps in a range of 20-50 meters from where we are now.
This come from my mountainery experience essentialy with snow and winds.

[Nomadd22]

I know there isn't any doubt but just to reiterate the recent changes have almost all been about cleaning. At the end of March she was generating 223 watt-hours per sol, with a dust factor of 0.297 - basically 70% of possible energy was being blocked by the dust on the panels. Tau was also a bit high then at 1.19 which in effect dropped the power down by about 25-30% compared to where it is now (with Tau at 0.8).

Waaay back on Sol 577 over on Husband Hill (The first Summer Solsitice) she was generating ~900-950W-hr when Tau was at 0.8-0.9. And that was basically pristinely clean.

So now we have 656Whr at almost exactly the same time, with the same opacity. That's not pristine but it is amazing. The very first confirmed power number that I have for Spirit was 700Whr on Sol 80 although it has to be said that the actual insolation at that time was about 20% below the levels that is is right now because it was just after the SH Autumnal Equinox.

It couldn't have happened to a nicer Rover. :)

I would have expected some solar panel degradation (20%?) just from their advanced age. (Sort of like my knees) I may be a little behind on the technology, or it might be a lot less of a problem at martian light levels.

[djellison]

I would have expected some solar panel degradation (20%?) just from their advanced age.

http://zeus.nascom.nasa.gov/~bfleck/SOHO/SaDeg.pdf

In deep space - closer to the sun - 13% in 6 years. I'm not sure what the contributing factors are. MER arrays are 50% further from the sun, and exposed to that sun only 50% of the time - so if sun-bathing (i.e. radiation effects) are the primary cause, then with a similar performance drop off, MER arrays would be be <5% of initial performance.

I would imagine, however, it would be impossible to separate array degradation (however small) from dust obstruction (significantly larger)

At the summit of Husband hill - so after >500 sols - Spirit was generating more electricity than the day it landed.

[helvick]

I'm not 100% certain what the expected standard degradation rate is for the specific arrays on the MER's but for the GAInP\GaAs cell types that are used on them it is expected to be about 0.5% pa. So that's somewhere around 2.5% at this point rather than 20%. [ http://trs-new.jpl.nasa.gov/dspace/bitstre...3/1/04-2642.pdf ]. That's pretty good - I thought it was actually around 2-3% pa which would have made a much more noticeable dent in the potential energy generating capability.

[fredk]

New images of the solar panels, from sol 1902. Looking pretty nice!
http://qt.exploratorium.edu/mars/spirit/na...DNP1943R0M1.JPG
Can anyone identify the circular, out-of-focus, bright area in the extreme lower right corner of this frame? The same foreground feature appears in exactly the same part of this frame, although the background has changed:
http://qt.exploratorium.edu/mars/spirit/na...DNP1943R0M1.JPG

[djellison]

Pancam lens dustcovers - what pancam was looking out thru cruise - I think.

http://mpfwww.jpl.nasa.gov/mer/gallery/spa...mer2_021003.jpg

[RoverDriver]

New images of the solar panels, from sol 1902. Looking pretty nice!
...
...

These images were taken to assess the state of the middle wheels which can be seen through the opening in the deck.

Paolo

[fredk]

Thanks, Paolo, I don't think even the sharp eyed members of UMSF would have noticed that! It makes sense that the current emphasis would be on mobility rather than characterizing the panels.