SCIENCE UPDATE

The backbone of the DNA molecule might have formed in space. Subsequently, asteroids brought the compounds to Earth – and perhaps many other worlds.

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The element of phosphorus is vital for life on Earth. Phosphorus is included in the make-up of our cell membranes, helps keep all cells alive, and is the backbone of the formula of life itself, DNA. Without phosphorus, life as we know it would not exist.

Phosphorus can only be used in the building blocks of life, if it is included in water-soluble compounds such as phosphate and phosphoric acid, but scientists used to have no idea where Earth’s water-soluble phosphorus compounds originally came from. Now, scientists from the University of Hawaii, USA, have shown that the vital phosphorus molecules might have formed in space, after which they were carried to Earth by comets and asteroids.

Asteroids include the phosphane molecule: a phosphorus compound that is toxic for all living organisms. If phosphane can be converted into phosphate and phosphoric acid in space, it is likely that asteroids brought the substances to Earth. To test the theory, the chemists imitated the conditions on the surface of an asteroid and added phosphane. When the scientists aimed electron radiation like that of space at the phosphane molecules in a pressure chamber, the bindings between the substance’s atoms were broken, so phosphorus could enter into other compounds and produce phosphoric acid, as well as various others. So, scientists think that one of the most vital building blocks of life on Earth might have formed in space.

The discovery contributes to the understanding of where we come from, and it also makes it plausible that the phosphorus building blocks exist in many places - including other worlds.