By Will Dunham
WASHINGTON (Reuters) – Scientists have discovered how the subsurface ocean on Jupiter’s moon Europa may have formed and determined that this vast expanse of water may have supported microbial life in the past.
Europe, with an ocean hidden under a thick layer of ice, has long been viewed as a potential habitat for extraterrestrial life in our solar system, along with other candidates such as Mars and Saturn’s moon Enceladus. A new study presented Wednesday at a geoscience conference underscores its potential.
Europe’s ocean may have formed after water-rich minerals expelled its water from heating caused by the decomposition of radioactive elements within it early in its history, the researchers found.
The effect of the tides caused by Europe’s gravitational interactions with Jupiter, the largest planet in the solar system, and two other large Jovian moons, Io and Ganymede, may also have played a role.
“We believe that Europe’s ocean may have been habitable early when it formed because our models show that the composition of the ocean may have been only slightly acidic, containing carbon dioxide and some sulfate salts,” said planetary scientist Mohit Melwani Daswani of the NASA Jet Propulsion Laboratory, the study leader
“The availability of liquid water is the first step to habitability. Also, the chemical exchange between the ocean and the rocky interior may have been significant in the past, so potential life may have used chemical energy to survive.”
Daswani said microbes similar to certain bacteria on Earth that use carbon dioxide for energy could have survived using ingredients available in Europe’s first oceans.
Europe is slightly smaller than Earth’s moon. Europe’s ocean, perhaps 40 to 100 miles (65 to 160 km) deep, can hold twice the water of Earth’s oceans.
The study assessed whether Europe was previously habitable and did not examine its current habitability, a question that researchers are now exploring.
“A word of caution,” said Melwani Daswani. “If a place is habitable, it does not mean that it is actually inhabited, just that the conditions could allow the survival of some extremely resistant life forms that we know on Earth.”
(Reporting by Will Dunham; Sandra Maler’s Edition)