Scientists Create Life’s Building Blocks From Just Three Ingredients

Take dust and ice, add radiation, and voilà.

The Rosetta spacecraft took this image of comet 67P/Churyumov-Gerasimenko backlit by the sun on March 27. The creation of complex organic molecules in the lab is in line with the identification of organic molecules in cometary samples taken by Rosetta’s Philae lander.

Out in the cold emptiness of interstellar space, there’s an abundant supply of ice-coated dust particles that are bombarded regularly by radiation. Cornelia Meinert from the University of Nice in France and her colleagues decided to see what would happen if they simulated that environment in their lab, then irradiated water, methanol, and ammonia molecules in a specific ratio (10:3.5:1) with ultraviolet rays, so that the molecules disintegrated and reassembled as different compounds. The result was a rich yield of organic molecules, including some that are considered the building blocks of life. The products even included ribose, a five-sided sugar that supports the production of ATP (the main currency of energy for life on Earth) and is a central building block of RNA, which is the precursor of the nucleic acid DNA.

Finding the building blocks of life in space (and on comets and meteorites) is nothing new. What’s surprising about the new result is the sheer amount and diversity of complex organic molecules that resulted from this fairly simple procedure. The created organic compounds incorporated more than 3.5 percent of the total mass of the original molecules, and included sugars, sugar alcohols, and sugar acids, all of which were present well above trace quantities. The treasure trove also included components of other nucleic acids, which could have been the precursors of RNA. In addition, the samples were fully soluble in water, which means in principle they could have undergone more processing. Many are also soluble in methanol, raising the prospect that life could use other solvents in addition to water.

The study by the Meinert group gives further credence to the idea that life’s basic ingredients are ubiquitous in space, and that biology could be common on other planets. It doesn’t necessarily mean that life came from space, however. Life is still much more complicated than any of the compounds discovered in space so far, and needs the concerted interaction of many complex chemicals within a suitable solvent. This combination would most likely require a planetary surface to take hold, under conditions that still remain unknown.

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