Meteorites baked in Earth's hydrothermal vents might have released molecules crucial to forming cell-like membranes in early life forms. So suggest tests run on pieces of a van-sized meteor that broke up over California.
The meteor made headlines in April 2012 when it was spotted as a bright fireball over the US west. By tracking its trajectory, scientists were able to figure out where fragments should have landed and quickly collect relatively fresh pieces.
Initial tests on the pieces showed that the meteorite is a carbonaceous chondrite, a class that is usually rich in amino acids and other soluble, carbon-containing compounds. Scientists have theorised that these organics – key ingredients for life – dissolved from meteorites into Earth's seas.
But it turns out that Sutter's Mill was heated by collisions with other space rocks before it fell to Earth, which changed its composition. Other work found that the meteorite fragments seem to be oddly low in organic materials.
Hardly any soluble organics were found after boiling two more of the fragments, says Sandra Pizzarello of Arizona State University in Tempe. But her team also wanted to know how the insoluble material – the hardier and often ignored stuff in the meteorite – would withstand a six-day bake in extreme heat and pressures akin to those around hydrothermal vents, possible sites for the origin of life.
"And lo and behold, this meteorite left behind something we have never seen," says Pizzarello. The unexpected riches were polyether- and ester-containing compounds. These long molecular chains, which contain carbon and oxygen, are insoluble but float in water, much like soaps or oils. They can form scaffold-like structures and may have trapped other, soluble organics within the cell-like enclosures of early life forms, she says.
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