Mars Exploration Rover Update - December 23, 2004

http://marsrovers.jpl.nasa.gov/mission/status.html
SPIRIT UPDATE: Spirit Eats a Potato-Sized Rock - sol 333-345, December 23, 2004
Spirit finished work at a rock called "Wishstone," then continued to make slow progress up "Husband Hill." Wishstone is different than any rock Spirit previously studied either on the plains or in the hills. Scientists and engineers used the miniature thermal emission spectrometer to find similar rocks for further study.
A potato-sized rock got caught in Spirits's right rear wheel on sol 339, causing the wheel to stall and ending the drive for that sol. Small moves of the wheel on subsequent sols dislodged the rock, but the rock remains close to the wheel, so the team is planning small, careful steps to move the wheel away from the rock so it will not become jammed again. Spirit remains in excellent health.
Sol-by-sol Summaries:
Atmospheric observations using the miniature thermal emission spectrometer, navigation camera, and panoramic camera continue on a daily basis.
On sol 333, Spirit used the brush of the rock abrasion tool brush to scrub a small section of Wishstone and took microscopic images of the spot. Spirit then placed the alpha particle X-ray spectrometer on the spot for collecting data overnight.
On sol 334, Spirit removed the alpha particle X-ray spectrometer and then used the rock abrasion tool to drill into Wishstone. After taking more microscopic images, Spirit placed the alpha particle X-ray spectrometer on the hole for an overnight observation.
On sol 335, Spirit removed the alpha particle X-ray spectrometer from the hole and replaced it with the Mossbauer spectrometer. Spirit also started a long series of Mossbauer observations that would last until the early morning of sol 337.
On sol 337, Spirit stowed its robotic arm, then bumped backwards to take final images of Wishstone and the rock abrasion tool hole. Spirit was commanded to drive 15 meters (49 feet), but drove only about 6 meters (20 feet) due to experiencing slippage of up to 80 percent on uphill portions of the drive.
On sol 338, Spirit drove 8 meters (26 feet) with 25 meters (82 feet) of commanded motion. Spirit saw up to 95-percent slip on some of the drive segments due to sandy terrain and the rover's tilt of 15 to 20 degrees.
On sol 339, the rover team attempted another 25-meter (82-foot) drive. This was cut short at the start when the right rear wheel ingested a potato-sized rock. The rock apparently jammed between the inner part of the wheel and the drive mechanism, causing the drive current to exceed a pre-set limit, resulting in a safe motor stall.
Sol 340 - Spirit made observations with the miniature thermal emission spectrometer to seek other rock targets similar to Wishstone. Turning the right rear wheel about 60 degrees successfully un-jammed the rock, but it remained inside the wheel.
Sols 341, 342 and 343 were planned as a combined three-sol plan that included observations with the miniature thermal emission spectrometer each sol. On sol 341, Spirit used its microscopic imager and its Mossbauer spectrometer to examine disturbed soil in front of the rover. It switched to the alpha particle X-ray spectrometer overnight to gather more compositional information about the same target. On sol 342, Spirit performed a mid-day tool change back to the Mossbauer spectrometer. On sol 343, the rover stowed the robotic arm and took images with the panoramic camera of targets that had been observed with the miniature thermal emission spectrometer. Spirit then performed a small maneuver but did not significantly change the position of the rock in the wheel.
Sol 344 - Spirit performed more remote sensing and did a maneuver that lifted the right rear wheel slightly out of a hole, but the rock remains partially in the wheel. The wheel is about one-third buried in the soft soil, making it difficult for the rock to escape until the wheel gets out of the hole.
Sol 345 - Spirit successfully executed another small maneuver to get the right rear wheel out of hole and get the rock out of the wheel, but more steps will be required. The rover also used the panoramic camera and miniature thermal emission spectrometer to acquire information about nearby targets. Sol 345 ended on Dec. 22.
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What needs to be done to prove the source is biological is to gather enough evidence to falsify the non-biological hypothesis.
The aim of the mission is to gather as much information as possible, regardless of which hypothesis it may eventually support or eliminate.
George
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Simple logic, until you eliminate the alternative, the conclusion remains ambiguous.
have a very Merry Christmas, George
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A Rock Like None Before, Brushed. "Scientists viewed a rock like none seen before on Mars when NASA's Mars Exploration Rover Spirit brushed the surface and took magnified images of this rock dubbed "Wishstone." The circular area of interest, measuring approximately 5 centimeters (2 inches) in diameter, revealed darker pieces of material randomly distributed within a lighter-colored matrix. The rock has poorly sorted granular material, with grain sizes ranging from fine to coarse and some grains that are very angular in shape. Spirit used its microscopic imager on martian day, or sol, 333 (Dec. 9, 2004) to take the four individual frames that are combined into this mosaic view." http://marsrovers.jpl.nasa.gov/gallery/press/spirit/20041230a.html
Curious are the dark, smooth inclusions apparent in the rock. These might be similar to the smooth, glassy inclusions seen by Spirit in Humphrey and Mazatzal rocks. Alternatively, they could be examples of, apparent, sedimentary films seen at the Opportunity site:
From: snipped-for-privacy@yahoo.com (Robert Clark) Newsgroups: sci.astro,alt.sci.planetary,sci.geo.geology,sci.geo.mineralogy,sci.bio.misc
Subject: Sedimentary films at Opportunity site. Date: 18 Mar 2004 16:26:04 -0800 http://groups-beta.google.com/group/sci.astro/msg/11a829ece45426b7
Clays perhaps?
Bob Clark
snipped-for-privacy@earthlink.net wrote:

rock
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wrote:

Hmmm, they do bear a superficial resemblance to "rip-up clasts", but (later). Rip-up clasts are typically thin films of clay/ fine sediment/ occasionally bacterial mats which form on the surface of bulk sediment in both aquatic and sub-aerial circumstances, and which later get "ripped up" by rapidly moving fluid (a whirlwind, dust devil, or underwater debris-laden flow, possibly in a strongly seasonal environment) and incorporated into a new unit of sediment. Because the rip-up clasts have not shared the same transportational history as the rest of the grains in the new sedimentary deposit, they have different characteristics - frequently different grain size and rounding to the host sediment. BUT, such clasts are also typically thin (they tend to be the surface *film* from the pre-existing sediment, which has become indurated by exposure to changing chemistry at the sediment-fluid interface), and even with a preferred orientation to the (putative) clasts in the cited specimen, one would expect to see some more elongate sections through the (putative) clasts. These are not present. You could do some more sophisticated statistics on the shapes of the grains exposed on the flat surface ground by the RAT, but my (practiced) eyeball would put the grain shape at being "sub-elongated" only.
[SIDELINE Thinks - online version of the Rittenhouse comparator or the "Tapeworm"? > http://www.nlfb.de/grundwasser/produkte/alahabu/hbr-4.html mentions it's existence, but online images ... can't find any ; the standard references are

Incredible as it sounds, I came up with a sex link while searching for that second link ! ]
Where was I? Yeah - the lack of highly elongate sections to my mind rules out rip-up clasts as a reason for this change of texture. To my eye, it looks like a mesothermal deposit of something like chalcedony (loosely) in vughs in a volcanic or hypabyssal rock. What would loosely be called "agate" on earth, if it were banded. I note that a number of the low-relief, dark regions have [excuse me - new years morning, so time for a fire in the kitchen! Where was I again?] a radiating-arcuate fabric in the surrounding crystalline/ granular material. That is what I'd expect to see in volcanics with filled vugs. Nice picture, interesting structures.
--
Aidan Karley,
Aberdeen, Scotland,
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Thanks for the analysis. What do you think of the dark material on the right side, inside the rim of the RAT hole in this image of Wishing Well rock, which also is supposed to be high in phosphorus:
http://www.lipfordm.com/wtsi/p-2M158146955EFFA269P2959M2M1-90.jpg
It also has a soft appearance as the smooth, dark material in Wishstone rock. What materials other than clay might give this soft appearance?
Bob Clark
Aidan Karley wrote:
Robert Clark wrote:

films
sci.astro,alt.sci.planetary,sci.geo.geology,sci.geo.mineralogy,sci.bio.misc
clasts", but (later).

occasionally bacterial mats which form on the

circumstances, and which later get "ripped up" by rapidly

flow, possibly in a strongly seasonal environment)

clasts have not shared the same transportational

they have different characteristics - frequently

surface *film* from the pre-existing sediment,

sediment-fluid interface), and even with a

one would expect to see some more elongate

could do some more sophisticated statistics on

RAT, but my (practiced) eyeball would put the

the "Tapeworm"? >

standard references are

Jour. Sed. Petrology, Vol.223, pp: 117-119

two-dimensional sphericity." Journal

for that second link ! ]

mind rules out rip-up clasts as a reason for

like chalcedony (loosely) in vughs in a volcanic

it were banded. I note that a number of the

for a fire in the kitchen! Where was I

granular material. That is what I'd expect to see

0.021233
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Robert Clark wrote:

On the right side, parallel to the rim? That looks like the shadow of the rim to me. Compare the orientation of the shadow on the fracture at the rim near the 6:30 position. Otherwise it looks like a fairly normal medium-grained igneous rock. Some signs of primary porosity (vesicles?) at about 8:00. Looks rather leucocratic (but I've no indication of the wavelengths used in the imaging), which would have comparatively high proportions of incompatible elements, which would include phosphorus.
--
Aidan Karley,
Aberdeen, Scotland,
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Aidan Karley wrote:

I've
have
0.021233
Here is a close-up of part of this dark, soft material in this rock:
dark, soft material http://sciforums.com/attachment.php?attachmentid=3690
Bob Clar
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The APXS instrument showed Wishstone to be high in phosphorus:
PIA07191: Spirit View of 'Wishstone' (False Color) http://photojournal.jpl.nasa.gov/catalog/PIA07191
Clay is known to be highly absorptive of phosphorus because of its small grain size:
Reducing phosphorus in aquatic systems using modified clays. http://www.eidn.com.au/phos98.html
This page discusses the absorption of phosphorus on clays and other sedimentary materials:
13.3 Binding of phosphorus in sediments. http://lepo.it.da.ut.ee/~olli/eutr/html/htmlBook_98.html
However, I've been informed that the APXS, Pancam, and mini-TES do not have sufficient resolution to see if the phosphorus is concentrated in the dark, smooth inclusions. But perhaps the mini-TES could measure them if it were placed closer to the target rock than is usually done.
Bob Clark
Robert Clark wrote:

interest,
revealed
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sci.astro,alt.sci.planetary,sci.geo.geology,sci.geo.mineralogy,sci.bio.misc
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Robert Clark wrote:

not
in
to
The mini-TES viewport is the same as the Pancam. According to this page the Pancam is 1.3 meters above ground level and its resolution is 0.286 milliradians/pixel:
Pancams: Panoramic Cameras aboard the Mars Exploration Rovers. http://www.planetary.org/mars/mer-inst-pancam.html
That means it should be able to resolve something .286/1000 * 1.3 m .37 millimeters across. The RATTed area in the image on this page is supposed to be 5 cm across:
A Rock Like None Before, Brushed. http://marsrovers.jpl.nasa.gov/gallery/press/spirit/20041230a.html
On my monitor when I click on the link for the Browse Image, the magnified view of the RATTed area appears about 10 cm across on my screen and I measure some of larger dark inclusions on my screen as 4 mm across. This means the actual size of the larger inclusions should be about 2 millimeters across. This should be well within the resolving power of the Pancam. For the mini-TES though the resolving power is at best 8 milliradians, which means at 1.3 m it can resolve 8/1000 * 1.3 m = 10.4 mm, too large for the inclusions. Is there any way for the RAT arm to scrape off a portion of a rock and hold it close to the camera?
Bob Clark
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Robert Clark wrote:

I don't think there are any grasping capabilities on the rovers.
--
Aidan Karley,
Aberdeen, Scotland,
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Robert Clark wrote:

Which is not (in itself) incompatible with a number of igneous lithologies either..
--
Aidan Karley,
Aberdeen, Scotland,
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