The Europa Clipper may only need one ice grain to detect life on Jupiter’s ocean moon
A single grain of ice ejected from Jupiter’s ocean moon Europa could be enough to reveal evidence of alien life. “With suitable instrumentation, such as the SUrface Dust Analyzer (SUDA) on NASA’s Europa Clipper space probe, it might be easier than we thought to find life, or traces of it, on icy moons,” said Frank Postberg of Freie Universität Berlin. The Europa Clipper is scheduled to blast off in October 2024. It’s expected to arrive in 2030, then perform nearly 50 close flybys of Europa, skimming the icy surface at altitudes as low as 25 kilometres (16 miles). The mission’s primary objective is to learn more about the habitability of Europa’s subterranean ocean and the thickness of the ice shell above it.
In 2006, the Cassini mission to Saturn discovered plumes of water vapour belching out from Enceladus’ ocean through large fractures in the surface. Under the assumption that the Europa Clipper may also fly through an icy moon plume, scientists led by Fabian Klenner of the University of Washington in Seattle investigated whether SUDA might be able to detect any life carried up from the ocean on the plume. SUDA is designed to study particles of Europa’s surface ice and dust sputtered into space as the moon is constantly bombarded by micrometeorites, but perhaps it could analyse ice grains in the plumes, too.
Simulating high-velocity impacts of ice grains on the instrument in a laboratory would be pretty impractical, so instead Klenner’s team fired a thin, fast-moving jet of water vapour loaded with a bacterium called Sphingopyxis alaskensis into a vacuum chamber. S. alaskensis is found in seawater off the coast of Alaska, and is at home in cold temperatures surviving off few nutrients. It’s one of the closest things we have to a life form on Earth that could survive in Europa’s ocean.
More pertinently to the Europa Clipper’s potential for finding such life, the bacteria “are extremely small, capable of fitting into ice grains that are emitted from an ocean world like Enceladus or Europa,” said Klenner. The vacuum resulted in the water jet disintegrating into droplets that froze as ice grains. The grains were then studied with a mass spectrometer, mimicking how SUDA will study any grains that it picks up in real life.
The results of the experiment showed that S. alaskensis, or at least the parts of it that form ocean scum, could indeed be detected from studying just a single ice grain.