"Could the Meridiani Spherules be Surficial?" |
"Could the Meridiani Spherules be Surficial?" |
Jul 10 2007, 04:37 PM
Post
#1
|
|
Junior Member Group: Members Posts: 42 Joined: 2-July 07 Member No.: 2646 |
I have been reading the response to the reponse to impact-surge linked by Dr Burt in post 170. The MER team objects to the impact-spherule explanation because " The spherules are dispersed nearly uniformly across all strata." I agree that is a valid criticism. It is very much like Dr. Burt's criticism of the MER team's hypothesis, that spherule distributions are not consistent with any conceivable ground-water movement regime that should have controled the development of concretions. I agree strongly with this point of Dr. Burt's as well. Neither theory does a good job of explaining the distribution of the spherules. Also, neither theory does a good job of explaining why the spherules do not apparently disturb the bedding.
There may be a solution in a possibilty that I now raise with some trepidation. I think that there is a chance that the spherules are superficial, and not an integral part of the Meridiani strata at all. This probably sounds crazy to many readers, but before rejecting it outright remember that science is at kind of an impasse on this and could use a new idea. If the spherules are superficial this would explain a number of puzzling observations. The layering at Homeplate and Meridiani is most simply explained by impact-surge. It is elegantly and inescapably explained by impact-surge. The impact-surge authors have also tried to explain the Meridiani spherules as part an impact event. If doubts are raised that the spherules are integral to the deposit, this would not in any way be inconsistent with the impact-surge origin of the layered structure. On the contrary, an objection to impact surge would be removed. I intend to start another thread under Opportunity to discuss this question. The first posting should be mine and should be an organized outline of how it might be possible that the spherules have been mis-interpreted as part of the Meridiani layered deposit. I am working on it. If anyone wants to start in on me with the obvious objections, do it here for now. Maybe Dr. Burt would like to respond. No matter what the details of spherule formation in an impact or spherule deposition in the impact sediments, the very uniform distributions that we see are troublingly unlikely. Random distributions are possible from explosive dispersal but less likely than some kind of clustering because of the rapidly changing conditions in the surge cloud. The more-uniform-than-random distributions of spherules on rock characterised by MER-team analysis cannot be explained by impact surge. |
|
|
Jul 15 2007, 03:18 PM
Post
#2
|
|
Junior Member Group: Members Posts: 42 Joined: 2-July 07 Member No.: 2646 |
I just thought of another remarkable observation that the surficial spherule idea might help to explain. The MER team has estimated that about 2% of the total rock volume of the Eagle Crater outcrops is made up of spherules. Here is a pancam image from Endurance that shows large numbers of spherules clearly against a band of brighter rock:
http://marsrovers.jpl.nasa.gov/gallery/all...MIP2274L5M1.JPG This high density of spherules is surprising somehow. It asks a lot of the proposed aquifer, which has to be at least as deep as Endurance Crater and without significant water movement in the MER team scenario. How has it supplied the concretion materials in sufficient quantity to the entire volume of rock? If the spherules are present only as a surface concentration then the large numbers we see are not so remarkable. It is a weak line of argument, but I thought it worth adding because I think it has struck many observers intuitivlely that the spherules are strangely numerous in this rock. I think that there was a fork in the road very early in the interpretation of Eagle Crater that went by too fast and has never been revisited. At pancam scale, such as in the Endurance image above, one might imagine that the protruding spherules are stuck to the surface of the rock. When more closely examined with the MI it is clear that some spherules are embedded in the surface of the rock. From this observation the conclusion was reached that the spherules occur throughout the bedded sediments at densities similar to those we see at the surface. I think that this decision should be revisited. It is at this point that the paradoxes of the spherules distribution and relation to the bedding are created. If we remain skeptical that the spherules are present throughout the deposit, then the contradictions never appear. I think that for this reason alone the surficial spherule idea is worth investigating. |
|
|
Lo-Fi Version | Time is now: 22nd September 2024 - 12:44 PM |
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. |