IPB

Welcome Guest ( Log In | Register )

18 Pages V  « < 13 14 15 16 17 > »   
Reply to this topicStart new topic
ROVER WHEELS: Monitoring changes over time, NOTE: Read back through the thread to avoid repeating misconceptions
jmknapp
post Jun 23 2014, 05:45 PM
Post #211


Senior Member
****

Group: Members
Posts: 1334
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


--------------------
Go to the top of the page
 
+Quote Post
elakdawalla
post Jun 23 2014, 06:00 PM
Post #212


Bloggette par Excellence
****

Group: Admin
Posts: 4425
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 blog - @elakdawalla on Twitter - Please support unmannedspaceflight.com by donating here.
Go to the top of the page
 
+Quote Post
Tom Tamlyn
post Jun 24 2014, 03:35 AM
Post #213


Member
***

Group: Members
Posts: 274
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.
Go to the top of the page
 
+Quote Post
bobik
post Jun 24 2014, 06:44 AM
Post #214


Junior Member
**

Group: Members
Posts: 44
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?
Go to the top of the page
 
+Quote Post
jmknapp
post Jun 24 2014, 10:40 AM
Post #215


Senior Member
****

Group: Members
Posts: 1334
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.


--------------------
Go to the top of the page
 
+Quote Post
vikingmars
post Jun 24 2014, 11:07 AM
Post #216


Member
***

Group: Members
Posts: 602
Joined: 19-February 05
From: France, close to Paris & Meudon Observatory
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 ! smile.gif
Go to the top of the page
 
+Quote Post
Gerald
post Jul 4 2014, 08:23 PM
Post #217


Member
***

Group: Members
Posts: 850
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:
Attached Image
Attached Image
(Screenshots of this video.)
Go to the top of the page
 
+Quote Post
mcaplinger
post Jul 4 2014, 09:30 PM
Post #218


Senior Member
****

Group: Members
Posts: 1285
Joined: 13-September 05
Member No.: 497



QUOTE (Gerald @ Jul 4 2014, 01:23 PM) *
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.
Go to the top of the page
 
+Quote Post
Gerald
post Jul 5 2014, 03:04 PM
Post #219


Member
***

Group: Members
Posts: 850
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:
Attached Image
Go to the top of the page
 
+Quote Post
nprev
post Jul 5 2014, 08:41 PM
Post #220


Senior Member
****

Group: Moderator
Posts: 7022
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.
Go to the top of the page
 
+Quote Post
fredk
post Jul 5 2014, 09:08 PM
Post #221


Senior Member
****

Group: Members
Posts: 3180
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.
Go to the top of the page
 
+Quote Post
nprev
post Jul 5 2014, 09:26 PM
Post #222


Senior Member
****

Group: Moderator
Posts: 7022
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.
Go to the top of the page
 
+Quote Post
Astro0
post Jul 6 2014, 05:24 AM
Post #223


Senior Member
****

Group: Admin
Posts: 2819
Joined: 21-December 05
From: Canberra, Australia
Member No.: 615



That was really clingy soil on Sol 673. Right centre wheel.
Temporary patching on a few cracks wink.gif

Attached Image
Go to the top of the page
 
+Quote Post
jmknapp
post Aug 4 2014, 09:33 AM
Post #224


Senior Member
****

Group: Members
Posts: 1334
Joined: 9-February 04
From: Columbus OH USA
Member No.: 13



Ouch

Attached Image


--------------------
Go to the top of the page
 
+Quote Post
climber
post Aug 4 2014, 10:17 AM
Post #225


Senior Member
****

Group: Members
Posts: 2616
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...


--------------------
Go to the top of the page
 
+Quote Post

18 Pages V  « < 13 14 15 16 17 > » 
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 17th September 2014 - 05:32 AM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is a project of the Planetary Society and is funded by donations from visitors and members. Help keep this forum up and running by contributing here.