East side of Cape York, Sol 3040 - 3056 |
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East side of Cape York, Sol 3040 - 3056 |
 Aug 23 2012, 10:44 AM
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#61
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 Member  Group: Members Posts: 813 Joined: 29-December 05 From: NE Oh, USA Member No.: 627  |
Have we ever been on such hard ground?
Lower dust fraction possibly exposing clays minerals making then faintly visible from orbit? Craig |
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Aug 23 2012, 02:05 PM
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#62
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 Member Group: Admin Posts: 976 Joined: 29-September 06 From: Pasadena, CA - USA Member No.: 1200 |
QUOTE (belleraphon1 @ Aug 23 2012, 02:44 AM)  Have we ever been on such hard ground? Lower dust fraction possibly exposing clays minerals making then faintly visible from orbit? Craig We have been on really hard packed soil but usually we leave at least some markings. Here we are leaving hardly any! Never seen anything like it. 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.
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Aug 23 2012, 03:34 PM
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#63
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Member Group: Members Posts: 507 Joined: 10-September 08 Member No.: 4338 |
In reply 430 in the Exploration of Cape York thread of the MarsRoverBlog open forum, Hortonheardawho has an animation showing tracks that apparently faded in the space of only 3 minutes.
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Aug 23 2012, 05:32 PM
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#64
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Senior Member Group: Moderator Posts: 4279 Joined: 19-April 05 From: .br at .es Member No.: 253 |
Here's (part of) the mosaic taken by the navcam on sol 3049 i.e. the current position. There's a piece of ejecta (?) on sight, better seen on this pancam picture.
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Aug 23 2012, 05:55 PM
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#65
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 Senior Member Group: Members Posts: 4246 Joined: 17-January 05 Member No.: 152 |
This is another cool view. And we're starting to get a better look at the two dark smudges coming up:
In stereo, you can see that they're depressions, but very different from the crater in between them:
Perhaps they're related to Whim Creek? And a closeup of Goldstrike (meteorite?) is down too: http://qt.exploratorium.edu/mars/opportuni...2M1.JPG?sol3049 |
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Aug 23 2012, 06:05 PM
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#66
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Member Group: Admin Posts: 976 Joined: 29-September 06 From: Pasadena, CA - USA Member No.: 1200 |
QUOTE (marsophile @ Aug 23 2012, 07:34 AM) In reply 430 in the Exploration of Cape York thread of the MarsRoverBlog open forum, Hortonheardawho has an animation showing tracks that apparently faded in the space of only 3 minutes. Thanks for pointing me to this forum. I was not aware of it. The animation seems to be relative to Sol 3044, so it is the same kind of material we are currently driving on and there are barely any tracks visible. Oppy is driving on cement! 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.
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Aug 23 2012, 09:14 PM
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#67
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Senior Member Group: Members Posts: 1582 Joined: 14-October 05 From: Vermont Member No.: 530 |
The yellow forum had the unfortunate tendency to degenerate into xenopomorphizing rocks. High noise to signal.
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Aug 24 2012, 10:51 AM
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#68
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Member Group: Members Posts: 813 Joined: 29-December 05 From: NE Oh, USA Member No.: 627 |
QUOTE (marsophile @ Aug 23 2012, 10:34 AM) In reply 430 in the Exploration of Cape York thread of the MarsRoverBlog open forum, Hortonheardawho has an animation showing tracks that apparently faded in the space of only 3 minutes. Thanks Paolo and marsophile for your replies. Was not aware of the forum above either. Wow.... what a fascinating change! |
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Aug 24 2012, 12:01 PM
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#69
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Newbie Group: Members Posts: 4 Joined: 14-August 12 Member No.: 6557 |
QUOTE (RoverDriver @ Aug 23 2012, 02:22 AM) I have never seen any VO image that was affected by glare from either rover. And tosol VO failure is not due to glare either. Typically we point the cameras down at about 30 deg below the horizon to have a good view of the tracks. With such a low elevation angle it is difficult to have glare. Even Autonav pointing is pretty low as well. Here, as I was saying earlier, there were no features to track (remember the on-board processing uses 256x256 pixel images) and there were no track markings on the ground. Even if we had pointed teh NAVCAMs straight down it would have been likely that VO would have failed. The glare in the post-drive NAVCAMs is mostly due to the dust deposition on the lens. Post drive NAVs are usually taken at -17 deg elevation and in early afternoon. Leave a digital camera for 8+ years in the desert, lens cap off, then try to take a picture late in the afternoon while pointing the camera at the horizon to the West. Assuming the shutter release still works after 8 years, that is.  One of the optical engineers (Reg Wilson) published a paper on the effects of dust deposits on the lens and CCD sensor. I don't have a reference, but if you look up Reg Wilson on the JPL web site very likely he has that paper listed. Paolo Thanks for the reply Paolo, very useful information. I wonder, when operating the rover are lighting conditions a constraint on the time period it may drive (I'd think at some point the images become too dark to operate visual odometry properly), or if other things restrict it before it comes to that, like power? Very interesting to see that the rover is barely leaving any tracks! I love that 8+ years later Opportunity is still amazing us. Rob |
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Aug 24 2012, 02:25 PM
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#70
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Member Group: Members Posts: 813 Joined: 29-December 05 From: NE Oh, USA Member No.: 627 |
QUOTE (belleraphon1 @ Aug 24 2012, 05:51 AM) Thanks Paolo and marsophile for your replies. Was not aware of the forum above either. Wow.... what a fascinating change! In an attempt to keep my own SNR level up (sometimes hard) could the ‘change’ seen from the Opportunity image 398419876 to 398420030 be just a lighting or filter effect? Fading Wheel tracks???? http://qt.exploratorium.edu/mars/opportuni...H0F0006R0M1.JPG http://qt.exploratorium.edu/mars/opportuni...H2F0006L0M1.JPG Some mornings I really need to curb my enthusiasm. Craig |
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Aug 24 2012, 02:46 PM
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#71
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Senior Member Group: Members Posts: 4246 Joined: 17-January 05 Member No.: 152 |
Better to compare the two left frames or the two right frames to minimize viewing angle differences:
http://qt.exploratorium.edu/mars/opportuni...0M1.JPG?sol3044 http://qt.exploratorium.edu/mars/opportuni...0M1.JPG?sol3044 I'd be surprized if this was a lighting effect, since at midday the sun's pretty high, and the effect we're seeing is not too far below the horizon, so not where you'd be catching reflections from the sun. Plus the two frames are only a couple of minutes apart. And they have identical filters. IIRC, we have seen similar things over longer intervals after wind gusts. So one guess is we had a good strong gust between these two frames almost erase the tracks. BTW, another lovely shadow-reaching-into-the-crater shot: http://qt.exploratorium.edu/mars/opportuni...0M1.JPG?sol3051 |
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Aug 24 2012, 02:53 PM
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#72
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 Senior Member Group: Members Posts: 2173 Joined: 28-December 04 From: Florida, USA Member No.: 132 |
QUOTE (fredk @ Aug 24 2012, 10:46 AM) ...one guess is we had a good strong gust between these two frames almost erase the tracks.... Any sign of a cleaning event on the solar panels?
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Aug 24 2012, 03:05 PM
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#73
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Member Group: Members Posts: 813 Joined: 29-December 05 From: NE Oh, USA Member No.: 627 |
Thanks fredk....
just not used to what seems (to me) such an abrupt change. Craig |
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Aug 24 2012, 03:54 PM
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#74
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Member Group: Admin Posts: 976 Joined: 29-September 06 From: Pasadena, CA - USA Member No.: 1200 |
QUOTE (neorobo @ Aug 24 2012, 04:01 AM) Thanks for the reply Paolo, very useful information. I wonder, when operating the rover are lighting conditions a constraint on the time period it may drive (I'd think at some point the images become too dark to operate visual odometry properly), or if other things restrict it before it comes to that, like power? Very interesting to see that the rover is barely leaving any tracks! I love that 8+ years later Opportunity is still amazing us. Rob Lighting conditions have never been an issue for driving as we typically try to drive "blind" (no VO or Autonav). Lighting conditions are usually always analyzed when using the MI as we try to avoid frames where part of the target is in direct sunlight and part is in shadow. If it is required, we sometimes change the IDD configuration to use a different wrist position and very rarely we have moved teh time when the IDD sequence begins to have more favorable Sun position. This is what happened so far but I guess that our current position it might not be a bad idea to think about lighting conditions for driving as well. 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.
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Aug 24 2012, 06:18 PM
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#75
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Founder Group: Chairman Posts: 14432 Joined: 8-February 04 Member No.: 1 |
QUOTE (fredk @ Aug 24 2012, 07:46 AM) So one guess is we had a good strong gust between these two frames almost erase the tracks. Looking at this near concrete like surface - it reminds me of desert pavement - ( http://www2.mcdaniel.edu/Biology/wildameri...sertgeolgy.html ) - lots of strong winds over time blow away what little dust is there and leave behind small pebbles etc settled into an almost hard packed surface. Those winds I'd bet are fairly consistently high, what with a tens of miles run up from the East. Thus - rover drives over a surface that's not been touched by anything but wind for Gy's - and pushes a few pebbles down, pushes a bit of dirt around. That wind is, very quickly, going to get that dirt out of there and 'rebuild' back to the pavement formation where the dirt is now hidden from the wind between the pebbles. We saw it happen on tracks we re-visited outside Endurance crater - but here it's just happened much quicker. |
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