The last vital ingredient for life has been discovered on Enceladus
Phosphorus, though rare on Earth’s surface, may be abundant on other worlds
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Many researchers consider Enceladus to be among the most likely places to house extraterrestrial life. It’s a world encased in ice, with an ocean of salty water hidden beneath (SN: 11/6/17). What’s more, in 2005 the Cassini spacecraft observed geysers blasting vapor and ice grains out of Enceladus’ icy shell (SN: 8/23/05). And in that space-faring spray, scientists have detected .But until now, researchers weren’t sure if phosphorus also existed on Enceladus. On Earth’s surface, the element is relatively scarce. Much of the phosphorus is locked away in minerals, and its availability often controls the pace at which life can proliferate. So Sekine and colleagues analyzed chemical data, collected by the now-defunct Cassini, of particles in Saturn’s E ring, a halo of material ejected from Enceladus’ jets that wraps around Saturn. Some ice grains in the E ring are enriched in a phosphorus compound called sodium phosphate, the researchers found. They estimate that a kilogram of water from Enceladus’ ocean contains roughly 1 to 20 millimoles of phosphate, a concentration thousands of times greater than in Earth’s big blue ocean.
At the floor of Enceladus’ subsurface ocean, phosphate may arise from reactions between seawater and a phosphate-bearing mineral called apatite, Sekine said, before being ejected through geysers into space. Apatite is often found in carbonaceous chondrites, a primitive, planet-building material (SN: 7/14/17).