Images from a long-dead NASA spacecraft have revealed what may be water vapour plumes rising from the surface of Jupiter’s moon Europa, bolstering hopes it could harbour life.

In 1997, NASA’s Jupiter probe, Galileo spacecraft, observed a bend in Europa’s magnetic field during a flyby.

The remarkable discovery was only unearthed more than 20 years after the project, when scientists, using NASA’s Hubble Space Telescope, spotted a geyser gushing through the moon’s frozen crust from a subsurface ocean.

“Europa’s ocean is considered to be one of the most promising places that could potentially harbour life in the solar system,” said Geoff Yoder, deputy associate administrator of the NASA Science Mission Directorate.

“These plumes, if they do indeed exist, may provide another way to sample Europa’s subsurface.”

The research, published in the journal Nature Astronomy, found evidence to “support the ocean theory”, which raises the possibility of gathering samples from beneath the surface without having to land on or drill through the ice.

Europa has a huge global ocean containing twice as much water as Earth’s oceans, but it is protected by a layer of extremely cold and hard ice of unknown thickness.

New evidence of liquid water on Europa is “worth exploring” because this moon could have the potential to sustain life, Monash University astronomer Dr Michael Brown said.

“It might be a long shot and one has to be really, really cautious but I think it’s one of the most promising places,” Dr Brown told The New Daily.

“It’s more evidence Europa has a subsurface ocean, but it’s going to be a very dark and cold ocean so could life survive there, is there enough energy to power life in that ocean under the surface? Those are very big question marks.

“Finding life on other planets or on moons is a huge gamechanger for our perspective on our place in the universe.”

Europa has “a lot of the ingredients necessary for life” – water, energy and carbon material, Johns Hopkins University Applied Physics Laboratory planetary scientist Elizabeth Turtle told Reuters.

“And one of the really exciting things about detection of a plume is that that means there may be ways that the material from the ocean – which is likely the most habitable part of Europa because it’s warmer and it’s protected from the radiation environment by the ice shell – to come out above the ice shell.

“And that means we’d be able to sample it.”

If confirmed, Europa would be the second moon in the solar system known to have water vapour plumes.

NASA estimates the plumes rise about 200 kilometres before raining material back down onto Europa’s surface.

Europa’s ocean resides under an estimated ice layer 15 to 25 kilometres thick, with an estimated depth of 60 to 150 kilometres.

-with wires