Meteroites carbon dating
Emily Chung covers science and technology for CBC News.She has previously worked as a digital journalist for CBC Ottawa and as an occasional producer at CBC's Quirks & Quarks. It could have started in ponds on the planet's surface, after meteorites splashed down and infused them with the building blocks of life, a new Canadian-led study suggests.The study authored by Ben Pearce, left, and Ralph Pudritz, suggests there were enough meteorites carrying the raw ingredients for RNA splashing into enough ponds in the early Earth to produce ample opportunities for RNA to form. The chemical building blocks of RNA molecules are called nucleobases, and they’ve been found in carbon-rich meteorites such as the Tagish Lake meteorite, which was found on a frozen lake in British Columbia in 2000.Using published data, Pearce and his colleagues estimated the number of ponds at the surface of the early Earth and the concentration of nucleobases in those ponds delivered by the meteorites splashing into them.They propose that those ponds may have dried up at some times of the year, concentrating the building blocks of RNA and allowing them to link together — something that's been shown to happen in the lab.To uncover the source of Earth's water, scientists look for bodies elsewhere in the solar system with similar water.
However, Rosetta has discovered that this comet possesses an even higher deuterium-to-hydrogen ratio than seen in Oort Cloud comets — three times the amount of heavy water compared to normal water as Earth has.
Rain would re-form the pond and mix up the building blocks, allowing them to link into longer chains the next time the pond dried up.
However, the RNA would have to have formed fairly quickly from its building blocks — within a few years.
In the future, when Comet 67P/C-G flies closer to the sun, the scientists hope to fly Rosetta through a jet of gas that the comet will give off as it gets warmer and more active.
This will help reveal if the deuterium-to-hydrogen ratio seen from the water near the comet's surface is the same as that from near its core."Hopefully, we'll get to fly directly through a jet [in the] summertime [of] next year," said Matt Taylor, ESA Rosetta project scientist.