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 |
Jun 23 2014, 05:45 PM
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#211
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Senior Member Group: Members Posts: 1465 Joined: 9-February 04 From: Columbus OH USA Member No.: 13 |
Ah, I should have looked back in this thread at some of your wheel maps. Looks like they've been doing this since about January?
As for what they did about it, does it refer to this item from February?: Curiosity Adds Reverse Driving for Wheel Protection -------------------- |
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Jun 23 2014, 06:00 PM
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#212
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Administrator Group: Admin Posts: 5172 Joined: 4-August 05 From: Pasadena, CA, USA, Earth Member No.: 454 |
Yes, I expect the public event to just be the story behind how they determined they should drive backwards, and drive in valleys instead of on high ground -- a nice story about how you solve an unexpected problem on a distant planet! This story is neat in that it's an engineering problem but understanding how to solve it required very close cooperation with the science team, which is kind of unusual for solving problems with spacecraft.
-------------------- My website - My Patreon - @elakdawalla on Twitter - Please support unmannedspaceflight.com by donating here.
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Jun 24 2014, 03:35 AM
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#213
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Member Group: Members Posts: 444 Joined: 1-July 05 From: New York City Member No.: 424 |
Any prospect of a video replay (official or bootleg) of the July 16 talk by Grotzinger and Heverley? It looks as though it might be particularly interesting to our crowd.
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Jun 24 2014, 06:44 AM
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#214
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Member Group: Members Posts: 238 Joined: 28-October 12 Member No.: 6732 |
On June 9, the Washington Post featured an article on the MSL wheel issue.
QUOTE "What was happening to the wheels was a really big surprise to the team, and not a good one," said Curiosity project manager James Erickson. “We had done extensive testing on those wheels, but we didn’t do testing on extremely sharp and pointy rocks embedded into the ground. But it turns out that Mars has many, many of them." Project scientist John Grotzinger said the wheel issue "quickly became an epic-scale problem for the mission. . . . It’s a little like being told you’re critically ill. You don’t know how much longer you have, but you know it will be a rough road." By the way, will the wheel design need to be changed for the Mars 2020 mission? |
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Jun 24 2014, 10:40 AM
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#215
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Senior Member Group: Members Posts: 1465 Joined: 9-February 04 From: Columbus OH USA Member No.: 13 |
"Critically ill"? Nothing to see here but an "epic-scale problem." Glad they were able to pivot, literally.
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Jun 24 2014, 11:07 AM
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#216
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Senior Member Group: Members Posts: 1083 Joined: 19-February 05 From: Close to Meudon Observatory in France Member No.: 172 |
Everything you want to know about Martian wheels but are too afraid to ask...
https://archive.org/details/nasa_techdoc_19930008925 A JPL/University of Texas study done in 1991... Enjoy ! |
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Jul 4 2014, 08:23 PM
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#217
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Senior Member Group: Members Posts: 2346 Joined: 7-December 12 Member No.: 6780 |
[Disclaimer: The images of this post are not actual images from Mars.]
This provides an idea of how far you can go until a wheel fails: (Screenshots of this video.) |
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Jul 4 2014, 09:30 PM
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#218
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Senior Member Group: Members Posts: 2511 Joined: 13-September 05 Member No.: 497 |
This provides an idea of how far you can go until a wheel fails... The video is very interesting, but it doesn't describe exactly what is meant by "test to failure". Usually this has a very specific definition for a subsystem test like this. It's not clear to me that the rover would be unable to move with one or more wheels broken even this badly. -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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Jul 5 2014, 03:04 PM
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#219
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Senior Member Group: Members Posts: 2346 Joined: 7-December 12 Member No.: 6780 |
I'd also assume, that the principle of redundance on each subsystem level is applicable to the wheels, meaning one or two wheels should be redundant to some degree. But I've no link to a paper I could reference to, to underpin this assumption, just some extrapolation from the MER rovers.
... Here a Sol 679 image of a passenger on the right middle wheel: |
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Jul 5 2014, 08:41 PM
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#220
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Merciless Robot Group: Admin Posts: 8783 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
Has there been any attempt made to determine the composition of the rocks that are doing the damage? All I've seen is a reference to an unexpected number of 'small, pointy' rocks in the soil, so I've been assuming that these are shards of basaltic rock that seem to be ubiquitous at every landing site to date save Meridiani.
-------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Jul 5 2014, 09:08 PM
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#221
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Senior Member Group: Members Posts: 4246 Joined: 17-January 05 Member No.: 152 |
They could only do that statistically, since I doubt anyone has identified a particular rock punching a hole in a wheel.
Also it sounded like part of the problem was an underlying surface that didn't "give" when driving over a rock. Perhaps under those circumstances there are enough sufficiently sharp garden-variety pieces of basalt to do the damage. |
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Jul 5 2014, 09:26 PM
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#222
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Merciless Robot Group: Admin Posts: 8783 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
Ah, thanks, missed the part about the substrate. Wonder if perhaps the entire area has underlying hard-tack evaporites.
-------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Jul 6 2014, 05:24 AM
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#223
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Senior Member Group: Admin Posts: 3108 Joined: 21-December 05 From: Canberra, Australia Member No.: 615 |
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Aug 4 2014, 09:33 AM
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#224
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Senior Member Group: Members Posts: 1465 Joined: 9-February 04 From: Columbus OH USA Member No.: 13 |
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Aug 4 2014, 10:17 AM
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#225
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Senior Member Group: Members Posts: 2920 Joined: 14-February 06 From: Very close to the Pyrénées Mountains (France) Member No.: 682 |
They intended to write a nice "JPL" at regular space on the soil. Well, the message will be a bit confused now...
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