Jets of water from one of Saturn’s moons could harbour signs of alien life

Enceladus, one of the planet’s 83 moons, is one of the strongest contenders for finding life in the solar system because it has a warm saltwater ocean beneath a thick layer of ice.

Sending a probe through the ice cracks to take samples is tricky, but scientists have now confirmed that signs of life should be detectable in plumes of water vapour that shoot from the surface.

In a new study, experts at the University of Arizona and PSL Research University in Paris calculated that there could be enough life on Enceladus that cells and other organic molecules would be ejected through the plumes.

Dr Antonin Affholder, of the PSL Research University in Paris, said: “Our research shows that if a biosphere – a region with living organisms – is present in Enceladus’ ocean, signs of its existence could be picked up in plume material without the need to land or drill.

“Such a mission would require an orbiter to fly through the plume multiple times to collect lots of oceanic material.

“The definitive evidence of living cells caught on an alien world may remain elusive for generations. Until then, the fact that we can’t rule out life’s existence on Enceladus is probably the best we can do.”

Enceladus is already known to emit methane, which can be produced by living organisms.

However, because methane can also be produced by geological processes, it is not definitive proof of life.

Prof Regis Ferriere, the study’s senior author from the University of Arizona, said: “Clearly, sending a robot crawling through ice cracks and deep-diving down to the seafloor would not be easy.

“More realistic missions have been designed that would use upgraded instruments to sample the plumes like Cassini did, or even land on the moon’s surface.

“By simulating the data that a more prepared and advanced orbiting spacecraft would gather from just the plumes alone, our team has now shown that this approach would be enough to confidently determine whether or not there is life within Enceladus’ ocean without actually having to probe the depths of the moon.”