The discovery of shallow pockets of water on one of Jupiter's moons could indicate extra-terrestrial life is possible, say scientists.

Jupiter, the fifth planet from the sun, is thought to have 79 moons, and its Europa moon has long been a candidate for finding life in our solar system. This is due to its vast ocean, which is widely thought to contain liquid water - a vital ingredient for life.

This ocean was believed to buried 25-30 kilometres (15-17 miles) beneath the moon's icy shell making scientific study challenging. However, according to new research published in the journal Nature Communications, the water could be closer to the surface than previously thought.

The finding came partly by chance, when geophysicists studying an ice sheet in Greenland watched a presentation about Europa and spotted a feature they recognised, explained the study's senior author Dustin Schroeder, a geophysics professor at Stanford University.

They realised that the M-shaped icy crests on Greenland looked like smaller versions of double ridges on Europa, which are the most common feature on the moon.

The scientists used ice-penetrating radar to observe that Greenland's ridges were formed when water pockets around 30 metres (100 feet) below the ice sheet's surface refroze and fractured.

"This is particularly exciting, because scientists have been studying double ridges on Europa for more than 20 years and have not yet come to a definitive answer for how double ridges form," said lead study author Riley Culberg, an electrical engineering PhD student at Stanford.

"This was the first time that we were able to watch something similar happen on Earth and actually observe the subsurface processes that led to the formation of the ridges. If Europa's double ridges also form in this way, it suggests that shallow water pockets must have been (or maybe still are) extremely common."

NASA's mission

Jupiter's moon continues to intrigue scientists because the “ingredients” necessary for life—water, chemistry, and energy—might be present within the satellite’s ocean.

In 2024, NASA are launching a flagship robotic mission to explore Europa and investigate its habitability. Scheduled to launch in 2024. Expected to arrive in 2030, NASA plans to make dozens of close flybys, swooping as close as 25km from its surface.

Known as the Europa Clipper mission, it will interrogate the moon’s ice shell, ocean, composition, geology, and it will seek current activity including putative plumes.

The moon's ocean is predicted to have more water than all of Earth's seas combined, according to the Europa Clipper's website.

"If there is life in Europa, it almost certainly was completely independent from the origin of life on Earth... that would mean the origin of life must be pretty easy throughout the galaxy and beyond," NASA project scientist Dr Robert Pappalardo.