My note, a series of fortuitous events in nature must unfold for the giant impact model to be plausible and this report points to some.
Example, "With an impact velocity of somewhere around 20,000 mph (32,000 km/h) — relatively slow as impacts go — what happened next was nothing short of catastrophic."
"What happened next is a little hard to follow and depends a lot on exactly how the impact unfolded and what Theia was made of. But the general picture is that some stuff went flying away, never to return. Other stuff rained onto Earth's surface. And a big chunk remained in orbit. In as little as a few hours — or perhaps up to a century or more — that material coalesced into its own solid object: the moon."
"Some models suggest that a second moon, just a few hundred kilometers across, formed past the far side and then slowly approached the moon and pancaked itself. This would explain why the far side of the moon is lumpier than the near side. There's also the possibility that this wasn't a low-energy, glancing blow at all — that instead, the proto-Earth was spinning really quickly and then got nailed by Theia. This would have delivered more than enough energy to vaporize everything and create a doughnut-shaped ring of plasma known as a synestia."
"No matter what, this impact released a lot of energy — more than enough to turn the moon into a molten ball, more than enough to bring the KREEP elements together, and more than enough to mix Earth's original material and Theia's to create a set of common features between Earth's crust and the moon."
My observation. Too much energy and the proto-earth is destroyed. I have yet to see a complete list of all the variables needed to make the giant impact model work and how many depend upon luck in nature, not to destroy proto-earth.
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