From New Scientist, we learn “Meteorite cargo could solve origin-of-life riddle” (01 March 2011) Andy Coghlan because
A chemical vital for life on Earth may have arrived ready-made from space. Unexpectedly, a chondritic meteorite has been found to contain large amounts of ammonia, a nitrogen-rich chemical needed to form the basic building blocks of life, including proteins, DNA and RNA.
Just how early Earth acquired sufficient ammonia for life processes has been a puzzle because the gas is destroyed by sunlight, and the assumed early environment didn’t favour ammonia production. However, some enterprising researchers exposed chondritic meteorite dust to water at 300 ̊C, and then compressed it beneath 100 megapascals of pressure, to mimic early Earth conditions. The ammonia, they reported, yielded 60 per cent of the nitrogen in the resulting powder.
Kee says that buried within the meteorite dust, the ammonia would potentially be shielded from destruction by sunlight, and therefore able to participate in reactions to create the building blocks of life.
Pizzarello speculates that the meteorite must have originated from asteroids or other environments where ammonia was a dominant chemical.
I wonder whether origin of life theory, in principle, will ever get beyond speculation. Of course it is interesting; old cold cases usually are. It’s precisely the old and the cold that makes them so. But they are festooned with conjecture: may have, might have, could have … Then I am jolted back to reality by a simple question: What if the postmistress phoned and said, “O’Leary? There may be a package waiting here. It might be for you. It could have come from Saskatchewan.”
I don’t know about you, but I wouldn’t run out to collect it.