James Webb Telescope: The icy moon Enceladus spews out a massive plume of water

Astronomers have detected a massive plume of water vapor pouring into space from Enceladus, an icy moon of Saturn.

The 504-kilometre (313-mile) wide moon is well known for its geysers, but this one is particularly large.

The water current stretches for about 9,600 kilometers – a distance equivalent to flying from the UK to Japan.

Scientists are intrigued by Enceladus because its salty ocean beneath its surface – the source of water – can sustain essential conditions to support life.

NASA’s Cassini mission (2004-2017) gathered tantalizing clues to the necessary chemistry by regularly flying through geysers and taking water samples with its instruments — though it didn’t directly reveal the biology.

The new super plume was spied on by the James Webb Space Telescope. Previous observations have tracked steam emissions extending for hundreds of kilometres, but this geyser is on a different scale.

The European Space Agency (Esa) calculated the water flow rate to be about 300 liters per second. Issa said this would be enough to fill an Olympic-sized swimming pool in a few hours.

Webb was able to map the plume properties using a highly sensitive Near Infrared Spectroscopy (NIRSpec) instrument.

The instrument showed how much ejected vapor (about 30%) fuels a hazy torus of water co-located with one of Saturn’s famous rings – the so-called E-ring.

“The temperature on the surface of Enceladus is minus 200 degrees Celsius. It’s very cold,” commented Professor Catherine Heymans, Astronomer Royal Scotland.

“But in the core of the moon, we think it’s hot enough to heat this water. And that’s what causes these plumes to erupt.

“We know deep in our oceans on planet Earth, in conditions like these, that life can survive. That’s why we’re excited to see these big plumes on Enceladus. It will help us understand more about what’s going on, and how likely life is, but it won’t be life like mine.” And like you – it would be a deep sea bacterium,” she told the BBC.

Scientists have proposed a NASA mission called Enceladus Orbilander that will try to solve the open question about life.

As the name suggests, this mission will orbit the moon to sample geysers much like Cassini did–but with more advanced technology–and then descend to sample material on the surface.

If ever approved, the Orbilander will not fly for several decades due to other priorities.

Meanwhile, NASA and ESA have probes headed for the ice-covered moons of Jupiter. These bodies also contain oceans of water at depth and could actually be better candidates in the search for extraterrestrial life because they are much larger.

It is not known, for example, how long little Enceladus has retained water in all the liquid states important to supporting biology; The Moon may have been frozen for much of the solar system’s history, affecting its life credentials.

In contrast, it is likely that Jupiter’s larger moons, such as Europa (3,121 km in diameter) and Ganymede (5,268 km) have the heat energy to keep water in a liquid state over a much longer period of time.

A detailed write-up of Webb’s observations of Enceladus will appear shortly in the journal Nature Astronomy. Preprint is available here.