CAS News

Life on Jupiter's moon?

TAMPA, Fla. -- Those speculating on whether Jupiter’s moon, Europa, might be harboring life in a vast ocean underneath a thick layer of ice might now have the answer: probably not, according to a new study co-authored by a USF astrobiologist.

The ocean underneath the ice layer of Europa is likely too acidic to support larger life forms, dousing hopes by those who thought the indication of water on the Jupiter moon might be a place where extraterrestrial life could be found. The new chemical analysis by USF Assistant Professor of Geology Matthew Pasek and Richard Greenberg of the University of Arizona’s Department of Planetary Science, said the Europan sea environment is probably not friendly to marine life as we know it.

Space scientists have focused on Jupiter and Europa since the Galileo spacecraft, launched by the space shuttle Atlantis in 1989, provided scientists with decades of data to analyze. One of its most significant discoveries was the inference of a global salt water ocean some 100-miles deep on Europa. The ocean is estimated to be deep enough to cover the whole surface of Europa and contains more than three times the water of all of Earth's oceans combined.

On Earth, water generally means life -- but that’s not likely so on Europa, Pasek and Greenberg report in the journal Astrobiology after analyzing computer models of Europa’s ocean.

Oxygen is a major component of Europa’s crust. But unlike Earth with its photosynthetically-derived oxygen, the oxygen on Europa is formed by the high-energy bombardment of Europa’s surface by radiation, Pasek explains.

The scientists used computer models to calculate the predicted chemistry of Europa -- the same technology that’s designed to predict Earth’s groundwater chemistry or water chemistry at phosphate mines. After generating data on the inputs of oxygen descending into the crust, the scientists estimated the amount of material coming out of the rocks beneath the ocean.

The oxygen reacts with sulfur and other materials emanating from rocks at the bottom of the ocean. “When the two meet, they generate acid -- sulfuric acid in this case,” Pasek said. That would produce water with a pH of about 2.6, "about the same as your average soft drink," Pasek said. “Just as soft drinks are bad for your teeth as they are quite acidic, fish, corals, whales, or other large animals would find it difficult to live within the ocean of Europa.”

Those acidic levels would make it impossible for marine organisms like the ones found on Earth to grow shells or develop the way early marine organisms have here.

That said, if there is life on Europa, it might look more like the microbes found near acid mines in Spain who thrive in the Rio Tinto. Those organisms have evolved to oxidize iron and sulfide as energy sources, and tolerate environments even more acidic than those predicted for Europa.

"The microbes there have figured out ways of fighting their acidic environment," Pasek said. "If life did that on Europa, [Jupiter's moon] Ganymede, and maybe even Mars, that might have been quite advantageous."

The full paper can be read here.


Filed under:Arts and Sciences Geology Research   
Author: Vickie Chachere