The western route, 5th leg after stop at Absecon / Reeds Bay |
The western route, 5th leg after stop at Absecon / Reeds Bay |
Jul 11 2009, 05:57 PM
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Senior Member Group: Moderator Posts: 4279 Joined: 19-April 05 From: .br at .es Member No.: 253 |
Time for a new thread.
After moving southwards for ages, the "detour" by the western path has started with a 60+ meters drive on sol 1942. There are no images yet --they should be available on the next update-- so this image was calculated solely based on the rover's mobility info. I'll update the route map later. |
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Jul 29 2009, 11:33 PM
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Senior Member Group: Members Posts: 1045 Joined: 17-February 09 Member No.: 4605 |
On this sandblasted plane Block Island is large enough to have caused local wind variations and isn't it possible that the larger ripples in the immediate area could be attributable to this rather than crater remnants? If BI is ejecta rather than an asteroidal meteorite then the impact could well have been at terminal velocity for Mars or less. No more than 1 km/s? That wouldn't punch a particularly large hole. We could even be looking at ejecta from Victoria. So even if it does have the composition of an iron meteorite, if it is a fragment spalled from the Victoria meteorite on impact it would again have hit at less than terminal velocity.
If it is a Victoria impactor fragment spalled on impact and ejected does that make it ejecta or meteorite? |
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Jul 30 2009, 01:24 AM
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Senior Member Group: Members Posts: 2173 Joined: 28-December 04 From: Florida, USA Member No.: 132 |
...if it is a fragment spalled from the Victoria meteorite on impact.... My impression is that Victoria is too old for anything spalled from it's impactor to be lying on the current surface. Weren't we speculating a while back that Victoria* was formed before the hundreds of meters of sediment that Opportunity is traveling over were laid down? *edit: Oops, getting my craters mixed up.. That was Endeavor. But the speculation on Victoria was that it was so old that it has been covered over and uncovered by deposition and erosion, still making it impossible that the current surface could be the surface on which part of it's impactor fell. |
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Jul 30 2009, 04:49 AM
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Senior Member Group: Members Posts: 1045 Joined: 17-February 09 Member No.: 4605 |
But the speculation on Victoria was that it was so old that it has been covered over and uncovered by deposition and erosion, still making it impossible that the current surface could be the surface on which part of it's impactor fell. The line of demarkation between impact ejecta and the pre existing sandstone is pretty clear at Victoria. In places the breccia is almost eroded away. So wouldn't the surface away fropm the annulus be pretty much at the level it was at the time of impact? |
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Jul 30 2009, 03:57 PM
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Senior Member Group: Members Posts: 2173 Joined: 28-December 04 From: Florida, USA Member No.: 132 |
The line of demarkation between impact ejecta and the pre existing sandstone is pretty clear at Victoria.... So wouldn't the surface away from the annulus be pretty much at the level it was at the time of impact? So you're saying that when a crater is buried and subsequently revealed, ejecta and possibly detached pieces of the impactor would be covered and revealed just as the crater is, thus recreating the scene at the time of impact. Sounds good to me, but the process would also reveal all chunks of iron that had fallen to the surface after the crater was formed. The final result would be a removal of all soft material deposited since the crater's formation with a concentration of all resistant material -- berries and iron meteorites. There would be no way of telling if a chunk of iron on the surface fell at the time of the crater's formation or millions of years afterward. |
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