Stanley Miller performed some of the most famous origin of life experiments, showing that the chemicals thought to be present in the early Earth's atmosphere might react to form amino acids, the building blocks of proteins. But these experiments haven't aged well, through no fault of their own; other scientists have since revised their estimates of what was present in the early atmosphere, raising some doubts as to whether the Miller experiments are especially relevant. A paper released by Nature Chemistry neatly dodges this issue by showing that it might not matter what the Earth looked like—the shockwave of a comet impact can make biological materials regardless of the composition of the atmosphere it crashes into.
In the years since Miller's experiments, we've been better able to image the composition of comets, and have even returned samples of some of the material shed by the comet Wild 2 as it approached the Sun. These have revealed a mixture of simple organic compounds like ammonia and ethanol, but nothing as complex as an amino acid, chemicals that form the building blocks of proteins.
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