Joni Mitchell was right: We are stardust. Another one of the essential ingredients for life as we know it might have formed in space and then rained down on a young Earth, researchers suggest in the April 8 Science.
The simple sugar ribose — a crucial piece of the molecular machinery inside cells — can form on a blend of ices that have been blasted with ultraviolet radiation, chemist Cornelia Meinert of the University Nice Sophia Antipolis in France and colleagues report. These ices are common to comets and are thought to coat grains of interstellar dust that swirl around young stars.
“This is an amazing result,” says Conel Alexander, a planetary scientist at the Carnegie Institution for Science in Washington, D.C. Researchers have been looking at irradiated ices for years, he says, but have never seen ribose show up. Ribose is the backbone of RNA, a molecule that helps carry out the instructions encoded in genes. RNA is found in all life on Earth and might have been a precursor to DNA billions of years ago.
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