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.
In addition, H2 provides energy for some Earth microbes that produce methane from carbon dioxide, in a process called methanogenesis. Something similar could be happening on Enceladus, especially given that Cassini also spotted carbon dioxide, and a surprising bounty of methane, in the moon's plume.
"We wanted to know: Could Earth-like microbes that 'eat' the dihydrogen and produce methane explain the surprisingly large amount of methane detected by Cassini?" study co-lead author Régis Ferrière, an associate professor in the University of Arizona's Department of Ecology and Evolutionary Biology, said in a statement. TO READ ENTIRE ARTICLE, CLICK HERE...
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