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They found that the energy of the planetary smash-up would have partially melted Earth’s mantle, which would then have had two layers: a molten top and a mostly solid bottom.

The smash-up was “the first human experiment to deflect a celestial body”, says Thomas Zurbuchen, NASA’s associate administrator for science, and “an enormous success”.

Hiltz and Simpson were both involved in a smash-up just after the starting gun on a sweltering day at Hayward Field.

The finale diverges in numerous ways, but one is crucial: who causes the smash-up.

And this smash-up of claustrophobia and agoraphobia has proven to be an additional boon for Dungeons & Dragons.