Bullet-fast moon rocks carved 2 lunar gorges deeper than the Grand Canyon

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The lunar canyons Vallis Schrödinger and Vallis Planck are extraordinarily deep, and scientists now know the valleys were carved by bullet-fast moon rocks.

Bullet-fast moon rocks carved 2 lunar gorges deeper than the Grand Canyon : Read more

 

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Interesting article, and the paper it is based on is even more interesting.

Craters have the paradox that they are almost round regardless of the impact angle (well within bounds, the shallowest impact angles do produce oval craters). The basic level explanation has to do with the conservation of momentum an energy: most of the kinetic energy of the impacting object is turned into heat and a shock wave travelling through the impacted body outwards, turning into the kinetic energy of the ejecta (which has orders of magnitude higher mass than the impacting object), much of the moment is carried by a small portion of the ejecta that also has the highest velocity. But more detailed simulations (cited in the paper) show this is a simplification: at shallower impact angles, the original impact point will be at the uprange edge of the eventual crater, and the ejecta will leave in a butterfly pattern, with the fastest ejecta focused along certain directions, and the exact pattern depends on many factors (impact angle and speed, impactor size, surface gravity of the impacted object.)

Even the paper doesn't say so but the ejecta-produced canyons of the Schrödinger Basin still don't resemble any of the simulated patterns from earlier studies, in particular their angle. It's worth more research.