ROVER WHEELS: Monitoring changes over time, NOTE: Read back through the thread to avoid repeating misconceptions |
ROVER WHEELS: Monitoring changes over time, NOTE: Read back through the thread to avoid repeating misconceptions |
May 16 2013, 08:35 AM
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#1
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Junior Member Group: Members Posts: 22 Joined: 10-August 12 From: Australia Member No.: 6530 |
[MOD NOTE: This thread follows on a post by Ed Truthan containing a MAHLI mosaic of MSL wheels taken on sol 275.]
Ed: zooming in on that marvellous underbelly MAHLI montage, there appears to be further (and previously noted) deformation of the wheel surfaces. Damage is most evident in the view of the front-left wheel inner surface. Such wear has previously been discussed and concerns allayed. Nevertheless, the front left wheel surface *appears* to have been punctured. We've only done 700 meters, and have 7000 more to get to Mt Sharp..... Given that more odometry has now accumulated, is any (re-)new(ed) concern valid? DeanM |
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Dec 8 2013, 08:22 PM
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Senior Member Group: Members Posts: 2346 Joined: 7-December 12 Member No.: 6780 |
I'd like to see more emphasis on the wheels as a science instrument. Streaks, scratches, dents, holes, tears can be seen as measurements.
Here just some simplified ideas: Probably almost everyone working in mineralogy is best-familiar with determining scratch resistance or using streak plates. The frequency of scratches tells something about the abundancy of mineral grains harder than the aluminium alloy; streaks tell about cementation or about minerals softer than the alloy. More advanced are macroindentation tests, e.g. Brinell hardness tests. From known force, Brinell hardness of the wheel, and observed indentation the diameter of the indentor can be determined. The shape of indentations can e.g. be inferred from the shape of shadows. From known penetration and fracture propagation thresholds, lower bounds of the loads causing penetration can be inferred. From the driven distance the frequency per mars surface area can be calculated. So there are quantifyable data. Monitored wheel data could e.g. be used to cross-check a simulation of the mission. (Both images are regions of sol 476 MAHLI images, credit: NASA/JPL-Caltech/MSSS) |
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Dec 9 2013, 02:39 AM
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Founder Group: Chairman Posts: 14434 Joined: 8-February 04 Member No.: 1 |
I'd like to see more emphasis on the wheels as a science instrument. Streaks, scratches, dents, holes, tears can be seen as measurements. However - we will never know what they are a measurement of. Which rock/soil/pebble etc cause what damage. I'm afraid whilst your enthusiasm for this is admirable - there really isn't a legitimate means to extract quantitative data from this. |
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