Life on one of Saturn’s moons?
Hardy microbes like those found on Earth may also thrive in the oceans of Saturn’s sixth-largest moon, Enceladus, researchers in Austria have concluded. After 17 years collecting data on Saturn and its moons, NASA’s Cassini spacecraft has shown that Enceladus has an ocean beneath its ice-covered surface, and gas geysers near its southern pole. Cassini detected within these geysers life-supporting elements and compounds such as carbon dioxide, nitrogen, methane, and hydrogen—a cocktail of gases that would suggest the presence of hydrogen-consuming, methane-releasing microbes. To investigate this possibility, University of Vienna researchers simulated as best they could the conditions in Enceladus’ subsurface ocean, then examined whether three simple microbes could grow there. To their surprise, a bacteria-like microorganism that thrives without oxygen near deep hydrothermal vents on Earth was able to tolerate the Enceladus-like environment—even when the researchers harshened conditions by adjusting the temperature and pH levels. The findings don’t confirm the existence of alien extremophiles, reports TheAtlantic.com—but they do suggest that Enceladus is a good place to look for them, especially since its ocean is believed to have hydrothermal vents. Cassini scientist Hunter Waite says another flyby of the icy moon with “better instruments” could confirm the team’s conclusions by searching for the distinct chemical signatures of methane-releasing microbes. Someday, a robotic space submarine may conduct direct explorations. ■