4th leg in the trek to Endeavour, After science stop @ Kasos |
4th leg in the trek to Endeavour, After science stop @ Kasos |
Jun 7 2009, 07:32 PM
Post
#61
|
|
Member Group: Members Posts: 713 Joined: 30-March 05 Member No.: 223 |
|
|
|
Jun 8 2009, 02:01 AM
Post
#62
|
|
Member Group: Members Posts: 128 Joined: 28-October 08 From: Boston, MA Member No.: 4469 |
No, I think we will stop at the end of the next drive. Wherever that might be. What is the reasoning behind this? Is it due to excessive concern over the RF wheel currents, or because the future path alternatives diverge at this point? The reason I ask is that I would have thought it a priority to reach bedrock before stopping for any length of time (to maximize the science return during the rest). Mike |
|
|
Jun 8 2009, 02:28 AM
Post
#63
|
|
Member Group: Admin Posts: 976 Joined: 29-September 06 From: Pasadena, CA - USA Member No.: 1200 |
What is the reasoning behind this? Is it due to excessive concern over the RF wheel currents, or because the future path alternatives diverge at this point? The reason I ask is that I would have thought it a priority to reach bedrock before stopping for any length of time (to maximize the science return during the rest). Mike The only thing that helped reducing the RF current now seems to be resting for a week or two. The higher wheel currents indicate that the motor is subject to more mechanical resistance. I have not been following MER-B closely but was told that the nearest bedrock is about 200m away. At the current rate that would be about one week of driving. Paolo -------------------- Disclaimer: all opinions, ideas and information included here are my own,and should not be intended to represent opinion or policy of my employer.
|
|
|
Jun 8 2009, 10:05 PM
Post
#64
|
|
Senior Member Group: Moderator Posts: 2262 Joined: 9-February 04 From: Melbourne - Oz Member No.: 16 |
Just catching up a bit. Drive direction mosaics for sols 1897 to 1904 (all images link to the same blog entry)
Sol 1897 Sol 1898 Sol 1900 Sol 1902 Sol 1904 James -------------------- |
|
|
Jun 9 2009, 02:36 PM
Post
#65
|
|
Member Group: Members Posts: 279 Joined: 19-August 07 Member No.: 3299 |
The higher wheel currents indicate that the motor is subject to more mechanical resistance. I am suppossing that by driving on bedrock, the wheels traction will require less mechanical resistance than over the sand. Is there any difference of wheel currents between bedrock and sand? |
|
|
Jun 9 2009, 03:11 PM
Post
#66
|
|
Member Group: Admin Posts: 976 Joined: 29-September 06 From: Pasadena, CA - USA Member No.: 1200 |
I am suppossing that by driving on bedrock, the wheels traction will require less mechanical resistance than over the sand. Is there any difference of wheel currents between bedrock and sand? The RF currents drop to almost nominal (~50% reduction) on bedrock but all other wheels change only a slight amount (10% reduction). Paolo -------------------- Disclaimer: all opinions, ideas and information included here are my own,and should not be intended to represent opinion or policy of my employer.
|
|
|
Jun 9 2009, 08:56 PM
Post
#67
|
|
Member Group: Members Posts: 713 Joined: 30-March 05 Member No.: 223 |
The RF currents drop to almost nominal (~50% reduction) on bedrock Paolo Ah, this is very encouraging ! suggesting the RF problem will be greatly alleviated once we reach the firmer "parking-lot" type of terrain about 2 kms ahead (which is expected to be similar in driveability to the "easy" ground between Eagle and Endurance) ... so it sure is the most sensible approach to drive defensively in order to reach the "parking lot" with an intact RF |
|
|
Jun 9 2009, 11:44 PM
Post
#68
|
|
Member Group: Members Posts: 910 Joined: 4-September 06 From: Boston Member No.: 1102 |
-------------------- |
|
|
Jun 9 2009, 11:53 PM
Post
#69
|
|
Member Group: Admin Posts: 976 Joined: 29-September 06 From: Pasadena, CA - USA Member No.: 1200 |
I thought I was looking at Spirit tracks. What the hell--salts or silica in the middle of nowhere ... Funny, isnt' it? The penultimate drive tripped the average wheel current limit which is in place to stop the rover when it is close to being embedded. This is the first time this limit was triggered while not extricating the rover from an embedding event. Looking at the tracks, I think this was a good thing. Paolo -------------------- Disclaimer: all opinions, ideas and information included here are my own,and should not be intended to represent opinion or policy of my employer.
|
|
|
Jun 10 2009, 04:56 AM
Post
#70
|
|
Senior Member Group: Admin Posts: 3108 Joined: 21-December 05 From: Canberra, Australia Member No.: 615 |
|
|
|
Jun 10 2009, 05:35 AM
Post
#71
|
|
Merciless Robot Group: Admin Posts: 8783 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
Hmm. I see some apparent slip marks in the white patch. Given the wheel current spike, is the white stuff therefore more slippery than standard soil?
(And does this hold any clues for Spirit's situation? How many kinds of white stuff have been noted to date over in Gusev?) -------------------- 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.
|
|
|
Jun 10 2009, 06:41 AM
Post
#72
|
|
Senior Member Group: Members Posts: 1229 Joined: 24-December 05 From: The blue one in between the yellow and red ones. Member No.: 618 |
The little sliver of white to the upper left of the tracks suggests that we have ventured onto standard Meridiani bedrock with a very thin cover of sand.
-------------------- My Grandpa goes to Mars every day and all I get are these lousy T-shirts!
|
|
|
Jun 10 2009, 07:11 AM
Post
#73
|
|
Member Group: Members Posts: 239 Joined: 18-December 07 From: New York Member No.: 3982 |
|
|
|
Jun 10 2009, 10:08 AM
Post
#74
|
|
Member Group: Members Posts: 910 Joined: 4-September 06 From: Boston Member No.: 1102 |
The little sliver of white to the upper left of the tracks suggests that we have ventured onto standard Meridiani bedrock with a very thin cover of sand. No I would agree with briv1016 that it is not bedrock. I think we hit a patch of crumbly salt nodules. I think the larger rock/patch would also crumble if driven over. Paolo also indicated that wheel current was up from moving over/into soft soil--I don't think you would get that with a thin layer of sand over bedrock. I wonder if Opportunity will do any IDD work to explore the composition of the light material? -------------------- |
|
|
Jun 10 2009, 02:17 PM
Post
#75
|
|
Senior Member Group: Members Posts: 4246 Joined: 17-January 05 Member No.: 152 |
I don't see any sign of slippage in these images. The linear wheel track on the right isn't defined as well where it goes over the messy tracks from the turn in place. The lighter patches may just be patches where the compacted smooth fine soil is catching reflections of sun/skylight?
|
|
|
Lo-Fi Version | Time is now: 29th April 2024 - 09:16 AM |
RULES AND GUIDELINES Please read the Forum Rules and Guidelines before posting. IMAGE 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 funded by the Planetary Society. Please consider supporting our work and many other projects by donating to the Society or becoming a member. |