And it doesn't. But certainly these would-be Barsoomian geologists know that the rocks lying in the open, on the surface of Mars. . . have been subjected to extremes that any Earth-surface rock has never seen. While temperatures (minus 150 every night) are one factor, I think the more important one would be vastly increased Solar- (as well as background space-) radiation bombardments, over perhaps two billion years. That level of radiation -- over billions of years, could very well make a rock far more prone to crumbling. And here on Earth, perhaps 99.99 per cent of that radiation is slipstreamed away from our similar rocks, by our magnetosphere -- and protected, by a fine molecular blanket. . . of our relatively-thick atmosphere.
In sum, I think the rocks they are studying from the Southern California dry-gulches. . . are probably significantly sturdier than any of a similar age and weathering by anciently-haunting river-water, on Mars. High intensity radiation is known to weaken chemical bonds, and thus crystalline structures. Structures like those found at the microscopic level, in rocks. So too, it would stand to reason, even low level radiation, as a constant barrage -- over say 2 to 3 billion years. In any event, here is the latest, with a bit in blue below -- as of Valentine's Day 2022. I think they will still be able to get good core samples home to Earth. . . but the sample will be more fragile, than their Earth-based analogs might predict.
That in turn adds a new dimension to the level of tolerable shaking / vibration inside the return tubes (and thus immobilization / padding / buffering needed, for the return rocket ride home, come 2030 or so).
. . .Jandura’s team ran their flight-like drill a few millimeters at a time, stopping to check that a core was still forming; if it had crumbled, they’d look at variables that might be the cause. For instance, the engineers tweaked the drill’s rate of percussion and the weight placed on its bit. They also tried drilling into the rock horizontally instead of vertically, in case the build-up of debris was a factor.
For every adjustment they made, it seemed, a new wrinkle would emerge. One was that fragile samples can still resist the percussive drill. When Jandura’s team reduced the force of percussion to avoid powderizing the sample, the drill bit couldn’t penetrate the surface. But choosing a spot that holds up to stronger percussion means choosing one that likely interacted less with water.
Perseverance has so far captured six samples from highly weathered, water-altered rocks, and the team knows it’s capable of many more. But their experience with Roubion has prepared them for some of the extremes Mars will throw at Perseverance in the future. If they find more rocks like Roubion, the Extraterrestrial Materials Simulation Lab will be ready with its menagerie of Mars-worthy materials. . . .
Well -- now you know. Even very small changes. . . over these geologic time-frames. . . do have the real potential to change ultimate outcomes (even among voices that have long fallen. . . mute). Have a joyous and laughter-filled St. Valentine's evening, one and all. . . I know I plan to. Grin. . . .
नमस्ते
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