Europa is Jupiter’s sixth-largest moon, but it's smaller than Earth’s moon and hosts an ocean that may be twice the volume of Earth’s own. Now, new research presented at the Goldschmidt geosciences conference suggests that, based on how the Jovial moon’s ocean formed, Europa may have been capable of supporting life.
Researchers at the NASA’s Jet Propulsion Laboratory (JPL) developed a new computer model to demonstrate how radioactive heating inside of Europa could have caused the ocean to form, Will Dunham reports for Reuters. The ocean—positioned above the moon's layered interior—is blanketed with ice about 10 to 15 miles thick sits on top of the ocean.
The computer model shows that an internal heat source explains how the moon turned out that way, per Doris Elin Urrutia at Space. The heat, combined with the ocean’s liquid water and minerals, suggests that the ocean could even have supported life.
“We think Europa’s ocean may have been habitable early when it formed because our models show that the ocean’s composition may have been only mildly acidic, containing carbon dioxide and some sulfate salts,” JPL planetary scientist Mohit Melwani Daswani tells Reuters.
There are extreme forms of life on Earth that draw energy from hydrothermal vents deep under the sea, rather than from the sun. The model suggests that life on Europa would probably need to function in the same way, as Nicole Mortillaro reports for CBC News. Jupiter and its moons are too far from the sun to run on solar energy, so life would have to rely on chemical energy in Europa’s ocean.
But Melwani Daswani adds a word of caution, telling Reuters, “If a place is habitable, it does not mean that it is actually inhabited, just that the conditions could allow for the survival of some extremely hardy forms of life that we know of on Earth.”
Now, the heat from chemical energy combined with the gravitational forces from Jupiter and its other moons keeps Europa’s ocean liquid. And other large ocean worlds may have formed the through similar processes.
But the new research also illuminates differences between Europa and another oceanic moon that’s been a target in the search for alien life, Saturn’s Enceladus. Like Europa, Enceladus’ icy surface hides a deep underground ocean. But despite their similarities, these moons couldn’t have formed in the same way, Melwani Daswani says.
"[Enceladus] is a much smaller body than Europa and couldn't have experienced such high heat,” Melwani Daswani tells Space. “And we know this because Enceladus' density is much lower than Europa's density. The ocean must have been created by a different process."
NASA’s next opportunity to better analyze Europa’s habitability will come later this decade with the Europa Clipper mission. The satellite will analyze Europa’s ocean, ice shell and geology to directly measure the traits that could make or break its ability to support life.
In future research, Melwani Daswani plans to investigate whether there is enough chemical energy in Europa’s oceans to support life, Space reports.
"We don't even know whether life as we know it would be happy over there or whether the energy available for that for life would be sufficient," he tells CBC News.
Planetary geologist Gordon Osinski of London’s Western University, who wasn’t involved in the study, tells CBC News that the new research further emphasizes how intriguing ocean moons are.
"I think the key take-home here is that these ocean worlds present the best likelihood for present-day habitable environments," he says to CBC News. "So, life living on those planets at the present day. All the key ingredients are there."