Cassini, which has been circling Saturn and its entourage of moons since 2004, will end its mission in September with a suicidal plunge into Saturn’s atmosphere to avoid any chance of contaminating potential life on Enceladus. But even if Cassini could carry on for years, it was not designed to search for life.
“We’ve come as far as we can go, so it remains for a future mission to detect life at Enceladus,” Cassini project scientist Linda Spilker, with NASA’s Jet Propulsion Laboratory in Pasadena, Calif., told reporters on Thursday.
Ideally, scientists would like to drill through Enceladus’s ice cap and sample its underground ocean. An easier, lower-cost mission, however, would be to do what Cassini did, which is to fly through the plumes of material that continuously shoot out into space from the moon’s southern polar region.
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Besides measuring the ratio of hydrogen to carbon dioxide, which Cassini was able to do, there are several different chemical relationships that would be evidence of potential food sources for microbial life. A laundry list of those processes would be one of the things that a follow-on mission would look for, Waite noted.
Other options are to look for ratios of amino acids and structural patterns in fatty acids that are indicative of biology.
“There’d be a whole host of tests, and if you got green lights on all of them, then you’d have a pretty good idea that you had a high probability that life exists,” Waite said.
In the 2020s, NASA is planning to launch a spacecraft to Jupiter’s moon Europa, which, like Enceladus, has a salty ocean beneath its icy surface. The US space agency has not yet planned any follow-on missions for Enceladus, but it could be selected as the destination for a current or future round of planetary missions in the New Frontiers program. Proposals are due April 28.
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