NASA just detected water vapour on a moon of Jupiter — yet another clue that Europa's hidden ocean could hold alien life

NASA/JPL-CaltechAn artist’s rendering of NASA’s Europa Clipper spacecraft.

An icy moon of Jupiter is looking more and more like it could hold alien life deep in its subsurface sea.

On Monday, NASA announced that scientists had officially measured water vapour on the moon, called Europa, for the first time.

The discovery is yet another sign that Europa has all the right ingredients for aliens – given the right chemicals and a little deep-sea volcanic activity, it’s possible that life could spring up (or already has) deep in the saltwater ocean below Europa’s surface.

Here’s why scientists are increasingly looking to Europa in their hunt for alien life.


On Monday, NASA announced that scientists had measured water vapour on Europa for the first time.

NASA/JPL-Caltech/SETI InstituteHalf of Jupiter’s icy moon Europa as seen via images taken by NASA’s Galileo spacecraft in the late 1990s.

NASA’s Hubble Space Telescope first spotted such water vapour on Europa in 2013, possibly erupting from geysers. But nobody had directly measured it until now.


The discovery is yet another clue that Europa could host alien life.

NASA/ESA/K. Retherford/SWRIArtist’s concept of a plume of water vapour ejected off Europa.

“Essential chemical elements (carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulphur) and sources of energy, two of three requirements for life, are found all over the solar system. But the third – liquid water – is somewhat hard to find beyond Earth,” Lucas Paganini, a NASA planetary scientist who led the research, said in a press release. “While scientists have not yet detected liquid water directly, we’ve found the next best thing: water in vapour form.”


Scientists have long suspected that Europa conceals an ocean below its icy surface — possibly with twice the volume of Earth’s oceans.

Jenny Cheng and Skye Gould/Business InsiderScientists think Europa’s ocean contains twice as much liquid water as Earth.

Liquid water is promising, but it’s not enough. For life to arise, Europa needs two other ingredients: a few essential chemical elements, and a source of energy.

NASA/JPL-CaltechAn illustration of a submersible robot exploring the subsurface ocean of an icy moon.

The necessary chemical compounds seem to be abundant on the icy moon: Scientists think Europa first formed with carbon, hydrogen, nitrogen, oxygen, phosphorus and sulphur.

NASA/JPL/University of ArizonaThe thin, icy crust of Europa, blanketed in ice particles from a crater 1000 kilometers (620 miles) away. Minerals from water vapour paint the unblanketed surface a reddish brown. The colours in this picture were enhanced for visibility.

Asteroid impacts may have delivered even more life-giving elements.


In June, scientists spotted sodium chloride (also known as table salt) in Europa’s icy surface, indicating that the ocean below is more like Earth’s oceans than they previously thought.

NASA/JPL-CaltechAn artist’s concept of the ocean below Europa’s ice surface

Chemical reactions between this salt and rocks on the ocean floor could create nitrogen compounds, which are crucial in the formation of life.


But there’s one major problem: The sunlight that fuels life on Earth is 25 times fainter on Europa.

NASA/JPL-CaltechAn artist’s concept shows a simulated view from the potentially rough, icy surface of Jupiter’s moon Europa.

Even the most durable species on Earth, which have adapted to the most extreme conditions, would probably not survive on Europa.


But Europa’s oceans may be much warmer than its surface, thanks to its oval-shaped orbit around Jupiter.

NASA/JPLNASA’s Voyager 1 took this photo of Jupiter and two of its moons, Io (left) and Europa (right), on February 13, 1979.

Because it’s tidally locked, like our own moon, the same side of Europa is always facing Jupiter.

As Europa follows its oval-shaped orbit, its distance from Jupiter changes, so the difference between the gravitational pull on Europa’s two sides regularly grows and shrinks. These changes are called tides.


These tides stretch and relax Europa, cracking its surface ice and building friction that heats the moon from the inside.

NASA/JPLA cutaway image of Europa shows how Jupiter pulls unevenly on the two sides of the moon, creating tides and bulging.

That’s what keeps Europa’s subsurface ocean from freezing solid.


These tides could crack Europa’s mantle and give rise to deep-sea hydrothermal vents. On Earth, such vents produce intense heat that rips apart molecules and sparks chemical reactions.

OAR/National Undersea Research Program (NURP); NOAAA hydrothermal vent or ‘black smoker chimney.’

Earth’s hydrothermal vents form where seawater seeps into the planet’s rocky crust, meets volcanically active rock, and blasts back toward the surface.


Life on Earth crops up around these vents. These ecosystems don’t need sunlight to survive.

NOAA Office of Ocean Exploration and Research, 2016 Deepwater Exploration of the MarianasFluid from a hydrothermal vent chimney appears like dark smoke due to the high levels of minerals and sulfides it contains. The chimney is crawling with shrimp and crabs.

On land, food chains rely on plants to convert sunlight to sugar. But in the deep-sea food chain, microbes convert hydrogen to sugar. Rather than photosynthesis (which is fuelled by light), this process of “chemosynthesis” uses chemical reactions.


Nobody knows yet if Europa has deep-sea vents, much less alien life. NASA plans to investigate these questions with its Europa Clipper mission.

NASA/JPL-CaltechAn artist’s rendering of NASA’s Europa Clipper spacecraft.

The spacecraft is slated to fly close to the icy moon 45 times. NASA plans to launch it sometime in the 2020s.


The Clipper spacecraft is expected to fly through Europa’s water vapour plumes to analyse what might be in the ocean.

NASAAn illustration of salty ocean water spraying from the icy crust of Jupiter’s moon Europa.

Its radar tools will also measure the thickness of the ice and scan for subsurface water as the spacecraft gets as close as 16 miles to Europa’s surface.


That investigation could help scientists prepare to land a future spacecraft on Europa’s surface and punch through the ice.

NASA/JPL-CaltechAn artist’s rendering of a conceptual design for a potential future mission to land a robotic probe on Europa.

The future lander could search deep ice for signs of life in the ocean below, digging 4 inches below Europa’s surface to extract samples for analysis in a mini, on-the-go laboratory.

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