The methane wafting from Enceladus may be a sign that life teems in the Saturn moon’s subsurface sea, a new study reports.
In 2005, NASA’s Cassini Saturn orbiter discovered geysers blasting particles of water ice into space from “tiger stripe” fractures near Enceladus’ south pole. That material, which forms a plume that feeds Saturn’s E ring (the planet’s second-outermost ring), is thought to come from a huge ocean of liquid water that sloshes beneath the moon’s icy shell.
And there’s more than just water ice in the plume. During numerous close flybys of the 313-mile-wide (504 kilometers) Enceladus, Cassini spotted many other compounds as well — for example, dihydrogen (H2) and a variety of carbon-containing organic compounds, including methane (CH4).
The dihydrogen and methane are particularly intriguing to astrobiologists. The H2 is likely being produced by the interaction of rock and hot water on Enceladus’ seafloor, scientists have said, suggesting that the moon has deep-sea hydrothermal vents — the same type of environment that may have been life’s cradle here on Earth.