October 12, 2009--Saturn's icy moon Enceladus
may be the extraterrestrial body most likely to support life as we know it in our solar system, according to a new way to measure a world's fitness for life.
The Standard Microbial Habitability index rates worlds on a scale of 0 to 1 as to how suitable they are for microscopic life-forms like those on Earth.
"What's good for [microorganisms] is good for life in general," said research leader Abel Mendez, of the University of Puerto Rico at Arecibo.
Enceladus scored 0.4--the same as Earth.
Scientists think Enceladus's icy shell hides a vast under-ice ocean, and the moon's relatively small size means its internal pressure is not too great.
"The problem is the ocean could be very deep" beneath the ice, said Mendez, who presented his results October 5 at the 41st Annual Meeting of the Division for Planetary Sciences of the American Astronomical Society in Fajardo, Puerto Rico.
"If we want to explore it directly, it would be very hard."
Image courtesy Cassini Imaging Team, SSI, JPL, ESA, NASA