Mars Rover Spirit Mission Update Thread

[silylene old]

Jon: the distribution of pock marks tells us clues about the starting state. It's puzzling to me that no one ever thought it important enough to study before.<br /> <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[JonClarke]

I guess i expressed myself poorly.<br /><br />There has been a lot of work on aveolar or honeycomb weathering. Not only because it looks cool but because it can develop quickly (experimentally in a few weeks, in the real world over decades to centuries) and can cause serious degradation in stone structures.<br /><br />The weathering patterns are often controlled by pre-existing structure controls. If there is a rectalinear fabric in the examples that Spirit has discovered (and I am yet to be convinced of this), this would support such a control. Soemtimes small inhomogeneties such as clasts, diagenetic and weathering minerals, even concretions. However it can also develop in very homogeneous lithologies with no obvious source texture. Because the process involves positive feedback it destroys the feature that triggers formation of the individual pits and can be triggered by quite trivial variations. One can only extrapolate from what is known in the unweathered rock. But it is the overall process that is important, rather than the specific formation of an individual pit.<br /><br />Hope this is clearer.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[silylene old]

<i>The weathering patterns are often controlled by pre-existing structure controls. If there is a rectalinear fabric in the examples that Spirit has discovered (and I am yet to be convinced of this), this would support such a control.</i><br /><br />I agree, this needs a statistical test to establish whether the pits are random or correlated in a "rectalinear" pattern. I just note it does appear to be so.<br /><br />If the pits did form in a pattern, I am curious what might have been the original trigger. I know the formation of the pits destroys that evidence.<br /><br />You mention positive feedback cycles. Interesting! I have wirtten several papers on cellular automata models for percolative dissolution of polymer films (on a microscopic scale, not a macroscopic scale, such as this example).<br /><br />It's possible that a positive feedback between the process of pit formation and the pit of interest also affects the formation process of adjacent pits. I think it is possible this could lead to a "gridded appearance".<br /><br />In some ways, a positive feedback cycle on pit formation which affect the development of adjacent pits is reminiscent to me of some physiochemical feedbacks I am familiar with in liquid systems, such as Maringoni and Benard cell circulations, and Galvanic corrosion pit grids found in corroding metal alloys. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[JonClarke]

Hi silylene<br /><br />I can give you some journal references if you are interested.<br /><br />Cheers<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[silylene old]

Jon, PM me with a couple of references, or better a review article. I can order the article from work.<br /><br />Thank you for the offer! <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[JonClarke]

Here you go!<br /><br />McBride, E. F. and Picard, M. D. 2004. Origin of honeycombs and related weathering forms in Oligocene Macigno Sandstone, Tuscan coast near Livoorno, Italy. Earth Surface Processes and Landforms 29 713-735.<br /><br />Rodriguez-Navarro, C. 1998. Evidence of honeycomb weathering on Mars. Geophysical Rsearch Letters 25(17): 3249-3252.<br /><br />Rodriguez-Navarro, C., Doehne, E., and Sebastian, E. 1999. Origins of honeycomb weathering: role of salts and wind. Geological Society of America Bulletin 111: 1150-1255.<br /><br />Turkington, A. V. and Phillips, J. D. 2004. Cavernous weathering, dynamical instability and self-organisation. Earth Surface Processes and Landforms 29: 665-675. <br /><br />Enjoy!<br /><br />Cheers<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[ilbasso]

Spirit is having electrical problems now (per http://mer.rlproject.com/index.php?showtopic=394)<br /><br />"Newsflash: Spirit is having slight electrical problems now... <br /><br />There's a short between two grounds (power and chassis), which normally has a few kiloohms of resistance. This does not affect the operation in any way except that it makes it more vulnerable if there is a bigger problem somewhere else.<br /><br />Regarding the steering problem, Spirit is still experiencing intermittent problems. It is traveling with the steering actuators disabled, and turning like a tank.<br /><br />So, things are starting to happen now. Nothing lasts forever..."

 

[jaredgalen]

A case of the right wheel not knowing what the left wheel is doing.....bummer<br /><br />http://qt.exploratorium.edu/mars/spirit/forward_hazcam/2004-11-02/2F152649070EFF89A2P1201L0M1.JPG

 

[fangsheath]

This may be intentional, they may be running some tests on the steering systems. They certainly seem to be loitering in this general area with no clearly evident science objective.

 

[fangsheath]

The JPL website and a couple of articles suggest that the story of the Columbia Hills is beginning to come together, although few specific facts are provided. A consensus seems to be emerging that ground water is a big part of the story. One working hypothesis, put forward by Arvidson, is that the hills are volcanic ash beds that have been highly altered by ground water. He is quoted as expecting that eventually they will find evidence of past surface water in the hills as well.<br /><br />http://marsrovers.jpl.nasa.gov/newsroom/pressreleases/20041104a.html<br />http://www.chron.com/cs/CDA/ssistory.mpl/space/2885111<br /><br /><br />

 

[jaredgalen]

<br />Happy 300 Sol anniversary Spirit!!!!

 

[mikehoward]

Speaking of weird holes in rocks:<br /><br />http://qt.exploratorium.edu/mars/spirit/pancam/2004-11-10/2P153328458EFF89AIP2552L2M1.JPG

 

[centsworth_II]

Strange, how this "swiss cheese" phenomonon, which I don't recall seeing before the rover reached this area, should show up so prominently and so suddenly. I wonder how localized or widespead it will turn out to be. <div class="Discussion_UserSignature"> </div>

 

[centsworth_II]

It looks like Spirit saw similarly pitted rocks as it began its climb up West spur way back at the end of July.<br />http://qt.exploratorium.edu/mars/spirit/pancam/2004-07-30/2P144208697EFF7700P2557R1M1.JPG <br /><br />I don't know if these rocks are the same composition or the process that formed the pits is the same. It's strange that most of the rocks seen so far on West Spur have been remarkable (to me) in their smooth, curved surfaces, while nearby there are areas of rock with these myriad pitted features. <div class="Discussion_UserSignature"> </div>

 

[fangsheath]

It seems that the JPL engineers have satisfied themselves that Spirit's apparent steering issue is merely an instrumentation problem, and there is nothing actually wrong with the dynamic braking. Of course there is still the right front wheel friction issue, presumably they will continue to drive backwards for longer traverses.

 

[fangsheath]

I had a sense they were orienting the rover for a significant traverse, and sure enough it has driven backwards a considerable distance toward the east. We have gained some more altitude and the summit of Husband Hill is more inviting than ever.

 

[ilbasso]

Man, that's one dirty magnet! It looks almost like a sanding disc.

 

[CalliArcale]

I'm afraid the image was too big and choked the image approval tool. Could you try resizing it and reposting? <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[ilbasso]

I'll try again -- from the MI on sol 307:

 

[fangsheath]

Some idea of the current position of the rover can be gained by comparing the top image, posted on the Exploratorium web site yesterday, with the bottom, taken from the Clovis area. The jumble of light-colored rocks can be seen on the slope of Husband Hill in the bottom image near the midline of the image.<br /><br />We have made good progress eastward and are approaching what could arguably be called the transition between West Spur and the western slopes of Husband Hill.

 

[fangsheath]

Interesting, Spirit has continued eastward and is virtually back on the plain, apparently they are taking a bit of a short cut to the heights. I have indicated the approximate current location of the rover with a red dot, the presumed future path with a dashed line. This strategy also enables the vehicle to drive on relatively smooth, north-facing slopes, easing wear and tear on the mobility system and allowing substantial traverses with little risk of disaster. Recently the vehicle made a significant traverse driving forward, they may be wanting to get a clearer picture of the wheel friction and other mobility issues.

 

[fangsheath]

“sedimentology I think rules” -<br />a little Arvidson quote from the recent media teleconference regarding West Spur.<br /><br />The leading hypothesis at this point seems to be that West Spur consists of volcanic ash beds that have been highly modified by ground water. Three major pieces of evidence bear on this:<br /><br />(1) The rocks contain a mixture of angular and rounded grains, some rocks are clearly bedded, strongly indicating deposition in a fluid (atmosphere or water).<br />(2) Although silicate mineralogy is indicated, olivine is absent, pyroxene is uncommon, the rocks have an abundance of sulfur, chlorine, and bromine.<br />(3) The particles are not well sorted as would be expected if they had been deposited under water.<br /><br />It is also interesting that Arvidson notes that what little pyroxene they are finding seems to decrease as they gain elevation.<br /><br />I note that a week and a half after this conference, it is still not referred to on JPL’s MER site.<br /><br />http://www.jpl.nasa.gov/multimedia/

 

[fangsheath]

The rover continues in a generally eastward direction, but it is not clear to me if they intend to follow the course I have indicated above or run northeastward toward the nearer ridgetop. I get the impression they are carefully studying the terrain ahead before they commit one way or the other. The spur that runs northwest off of Husband Hill does look interesting.

 

[thechemist]

Maybe these maps from the MER forum will shed some light to all of us looking at recent Spirit images and feeling lost. <img src="/images/icons/wink.gif" /><br /><br />http://mer.rlproject.com/index.php?showtopic=486&st=30 <div class="Discussion_UserSignature"> <em>I feel better than James Brown.</em> </div>

 

[thechemist]

The following PanCam proves two things :<br />1. Some rocks in Gusev are really soft.<br />2. El Zorro was martian <img src="/images/icons/smile.gif" /><br /><br />http://qt.exploratorium.edu/mars/spirit/pancam/2004-11-24/2P154597052EFF9400P2292L2M1.JPG <div class="Discussion_UserSignature"> <em>I feel better than James Brown.</em> </div>