That's one small step for microbes, one giant leap for mankind's search for extraterrestrial life.
NASA's Saturn-exploring Cassini spacecraft has gathered new evidence that conditions on Enceladus, one of Saturn's 53 named moons, could support life, said Dr. Carolyn Porco, leader of the Cassini Imaging Team at the Space Science Institute in Boulder, Colorado.
"On Enceladus we have conditions under the surface that we know could be enjoyed by organisms similar to types of organisms we find right here on Earth," she said Friday.
Several years ago, Cassini, launched in 1997, spotted jet sprays shooting out of fissures called tiger stripes in Enceladus' southern polar region. Lighter particles from those jets provide most of the material for Saturn's outermost ring, called the E ring. But heavier particles fall back to the moon's surface, Porco explained. Cassini took measurements of the spray during three passes and found a greater concentration of sodium and potassium grains (that is, salt) nearer Enceladus' surface than farther out, according to a paper published in this week's edition of the journal Nature.
"There currently is no plausible way to produce a steady outflow of salt-rich grains from solid ice across all the tiger stripes other than saltwater under Enceladus' icy surface," Frank Postberg, a Cassini team scientist at the University of Heidelberg, Germany, and the lead author on the paper, said in an article on NASA's website.
"This finding is a crucial new piece of evidence showing that environmental conditions favorable to the emergence of life can be sustained on icy bodies orbiting gas giant planets," Nicolas Altobelli, the European Space Agency's project scientist for Cassini, added in the same article.
Of the particles that fall to the surface, 99% are salty; that means the water must be in contact with rock, which would create all the necessary conditions for life, Porco said.
"It's falling like snow," she said. "It's not crazy to think we could have snowing microbes."
Porco advocates sending a probe to land in Enceladus' tiger-stripe region to find out, because the evidence is so accessible.
"I think we should go directly to Enceladus," she said. "We should not pass 'Go,' we should not collect $200. ...
"All you have to do is land on the surface and stick your tongue out to sample the habitable zone," she said.
Porco, who has been working on the Cassini team for 21 years, hopes to live long enough to see definitive evidence for "a second genesis in our solar system."
"It would answer one of the greatest questions people have been asking ever since we could ask questions," she said.