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Thoughts on the Mars "Blueberries"
How the Mars "blueberries" formed:
The Martian surface was wet. Lots of muddy flats. Impacts on the flats. Mud, "atomized" and sprayed high in the cold, thin atmosphere, forms "hail stones" and rains back down as frozen "mud hail." Over millennia, thin atmosphere desiccates the "hailstones," leaving the freeze-dried "blueberries." One man's opinion. Kindly, David S. Jeffrey Cornish wrote: As metorite impacts are random events, and the debris from such impacts would likely be randomly sized, please explain the uniform size and distribution of the blueberries. You've make a very interesting hypothesis (don't try to hide behind opinion, you've given a mechanism for it occuring) What would disprove your hypothesis? Uniform distribution: We cannot really say this; the rovers have covered a vanishingly small fraction of the surface. Even if we do see blueberries over a wide area- the Martian atmosphere is not as dynamic as the Earth's and would have a similar effect on wet, fine-grained matter over a larger area. Given the consistent texture of the fine-grained component of impact ejecta on the Martian surface, consistent upper atmosphere dynamics over a large part of the planet and also given a surface covered either with a shallow brine sea or with saturated mud flats (the current model), the ejecta from large impacts (those capable of injecting matter into the upper atmosphere) would behave in a consistent manner. The blueberries we see are uniform in size for several reasons: The wet, pulverized particles ejected into the upper atmosphere would be "sorted" (larger particles falling out at lower altitudes), sending very fine-grain and water saturated material into the cold, windy Martian "stratosphere." As with Earthly hailstones, the energy of the fine-grain mud's motion, transferred into rotation as the particles froze and accumulated, acquire a rounded shape as their "spin" precludes further accumulation, the size of the spheres being dependent on many factors but mostly on these atmospheric effects, which we already know to be more uniform over a larger area than in an Earthly "thunderstorm." Earth storms generate hailstones of uniform size in this manner, their sphericial size dependent on the storm's dynamics over the area it covers. Since Martian atmospheric dynamics are still energetic but simpler, the similar-sized "mud hail" result would cover a much wider area with a consistent hailstone size. Lower gravity, lower atmospheric pressure, etc.- all contribute to a more uniform process over a larger area. And it's still just "one man's opinion;" I'm not smart enough to deal in hypothesis ;-). What would disprove it? Several things could- the first being general disuniformity in the internal structures or large-particle inclusions ( in the few we've seen "ground open," the structure has been fine and uniform, such as you would expect from the process I've posited). A closer study of the fine grain that supported slow accumulation as in the current "concretion" hypothesis would disprove it. Frankly, I think the lack of large inclusions stands against the "concretion" answer, along with other questions. I'm sure there are others- I guess we'll have to wait until someone actually has some blueberries to study. Don't hold your breath ;-). Kindly, David S. |
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