The ocean within Jupiter's moon Europa may be just right for life

Jupiter's icy moon Europa may have the chemical composition needed to support life, according to new research. 

A new study published in the journal Geophysical Research Letters suggests that even if Europa doesn't have hydrothermal volcanic activity beneath its icy crust, the moon's salty subsurface ocean may still be habitable, a possibility thought unlikely before now.

NASA scientists compared Europa's ability to produce hydrogen and oxygen -- two key elements for life as we know it -- to Earth's and discovered that the moon might have more in common with our planet than expected. 

"We're studying an alien ocean using methods developed to understand the movement of energy and nutrients in Earth's own systems," NASA scientist Steve Vance, co-author of the study, said in a statement. 

"The cycling of oxygen and hydrogen in Europa's ocean will be a major driver for Europa's ocean chemistry and any life there, just as it is on Earth."

On Earth, many basic life forms thrive near hot, volcanic vents in the deep ocean, but scientists aren't yet sure if Europa has similar activity percolating from its sea floor. 

How to make some alien hydrogen

For this study, NASA researchers only looked at processes on Europa and Earth that could release hydrogen and oxygen without volcanic activity. To their surprise, they discovered that the chemistry is similar on both worlds.

On Europa and Earth, "oxygen production is about 10 times higher than hydrogen production," NASA said.

Scientists originally thought that volcanic activity was necessary to create a habitable ocean on Europa, however, this new research shows that both hydrogen and oxygen can be produced at levels equivalent to Earth's oceans without volcanism, Vance said.

Original image has been replaced. Credit: Mashable

The study specifically looked at how much hydrogen is produced when the seawater of Europa's ocean interacts with rock on the seafloor. The water moves into small cracks in the rock, filling them in. This process, the study found, produces new minerals and releases hydrogen. 

Europa is still cooling off from its formation billions of years ago, and that cooling process likely creates new cracks where water can rush in and cause the release of more hydrogen, NASA said. 

"In Earth's oceanic crust, such fractures are believed to penetrate to a depth of 3 to 4 miles (5 to 6 kilometers)," NASA added. 

"On present-day Europa, the researchers expect water could reach as deep as 15 miles (25 kilometers) into the rocky interior, driving these key chemical reactions throughout a deeper fraction of Europa's seafloor."

Completing life's circuit

The study also examined the production of oxidants -- oxygen or other molecules that can interact with hydrogen. 

Oxidants are created on Europa when molecules at the moon's surface are bombarded with radiation from Jupiter, forcing water atoms to split. Some of these oxidants then get "cycled back" into the moon's subsurface ocean, according to NASA.

"The oxidants from the ice are like the positive terminal of a battery, and the chemicals from the seafloor, called reductants, are like the negative terminal," NASA scientist and co-author of the study Kevin Hand said in the statement. 

"Whether or not life and biological processes complete the circuit is part of what motivates our exploration of Europa."

NASA is hoping to send a spacecraft to Europa sometime in the 2020s, allowing the space agency to get a closer-than-ever look at the moon. Perhaps that mission will finally help scientists learn more about the icy object's potentially habitable ocean.

Have something to add to this story? Share it in the comments.