The moon is more complicated than we thought.
Up until a few years ago, everything relating to the creation of the moon seemed pretty much settled.
In 1975, William Hart and Donald Davis put forth the giant impact hypothesis, whereby a planetesimal or larger object caused the earth and the impact object to shed enough material to form a moon. Much of the hypothesis seemed to be confirmed by the Apollo moon rocks.
So, for more than 30 years, everything seemed settled.
But now an article entitled "Impact Theory Gets Whacked" by Daniel Clery in the 11 October 2013 issue of Science, reports that there are unsolvable flaws in the theory.
It seems that the isotopic composition of the moon rocks do not vary from the isotopic composition of rocks from the Earth, whereas all other rocks from space do vary noticeably. The giant impact hypothesis would require a large amount of the unearthlike material from the impact object to be present in the moon rocks. But it's not there.
This controversial information resulted in the first meeting in 15 years devoted to the formation of the moon at the Royal Society of London in September of 2013.
Several alternatives were suggested, but each alternative involved complicated side issues. The article quotes two of the participants: "We don't have a single scenario which stands out because of its simplicity," Canup said. Malosh agreed. "The solutions are contrived; they're not natural," he said. "We want a solution where isotopic similarity is a natural consequence of the model."
Well, if they want isotopic similarity as a natural consequence of the model, then we can give it to them.
When I was first presenting my antipodal impact ideas to the group last spring, Chuck B. disabused me of the notion that I could use simple impact extrusion of material from the mantle at the antipode of an impact for impacts that were of the size of the Chicxulub impact object. The object would have to be much larger.
In the case of the creation of the moon, we have no limitation on the size of the impact object. It can be as big as we need it to be in order to create a moon-sized object through the process of impact extrusion.
Since the moon rock material would be extruded from the mantle, along with some material from the surface, all of the moon rock would be rock from the Earth and none of the moon rock would be from the impact object.
To quote Chuck B.: "The only way the opposite side of the Earth would display near field impulse phenomena, is if the bolide collision were on a planetary scale, enough to overwhelm the dispersive properties of the rock. This would necessarily throw ejecta into orbit to create a satellite and liquify a portion of the planet. The evidence, in the form of a single moon, suggests that this at most only happened once, and it was at a time when the mantle was already mostly liquid."
So it looks like I might get to use my original impact extrusion mechanism on a one-time-only basis after all.