Colourful plumage: Artificially coloured image highlighting the extent of a plume of water vapour and gases emanating from the south pole of Enceladus. Now a flyby through the plume has hinted at the potential for life.
Credit: NASA
WASHINGTON DC: NASA's Cassini probe has detected conditions potentially suitable for life on Saturn's moon Enceladus, as it flew through giant plumes emanating from the south pole.
The spacecraft found a high density of water vapour and both simple and complex organic chemicals as it passed within 50 km of Enceladus on 12 March.
U.S. space agency NASA said on Wednesday that it had sent the probe to assess the geyser-like plumes shooting out from surface fractures.
Energetic fractures
Cassini's instruments detected temperatures on Enceladus's south pole hot-spot as high as -93ºC, which suggested that sub-surface temperatures might be high enough for the existence of liquid water, one of the keys to possible life, said John Spencer, one of the scientists on the Cassini team.
"It means we have a great deal of energy being delivered to the surface in this region," said Spencer, who works on Cassini's composite infrared spectrometer team at the Southwest Research Institute in Boulder, Colorado. "It's entirely possible that there's going to be liquid water not too far below the surface of these fractures."
"We see on Enceladus the three basic ingredients for the origin of life" – energy, organic compounds and water, said Larry Esposito also of the University of Colorado, who works on Cassini's ultraviolet imaging spectrograph.
Hunter Waite, another Cassini team scientist, said the spacecraft's instruments showed that composition of the plumes was much like that of many comets: "carbonated water with essence of natural gas."
Organics in abundance
The fly-by found increasing density of water vapour as Cassini sped through the plumes at 51,500 km/h. The plumes also carried a large volume of ice particles picked up from the moon's surface as they blast from fissures in the surface.
Also in the plumes, which feed into Saturn's E ring, were simple and complex organic materials like carbon monoxide and dioxide, methane, and propane, Waite said, a likely product of geochemistry in the moon's interior.
"The organics are clearly there in abundance beyond that we expected," said Waite, "The question that one would ask is that, where did the organics come from?"
What Cassini has found suggests that the 505-kilometre-diameter moon has significant potential for life, he added.
Hot on the heels of Titan
The Enceladus fly-by was the first of four planned this year to investigate the massive plumes emanating from the unique hot region, discovered by Cassini at the south pole in 2005.
The NASA report came days after scientists said in a paper that Cassini had supplied evidence for the possible existence of a subsurface ocean of water and ammonia on Titan, Saturn's largest moon.
"We believe that about 100 km beneath the ice and organic-rich surface is an internal ocean of liquid water mixed with ammonia," said Bryan Stiles of NASA's Jet Propulsion Laboratory in Pasadena, California, and one of the authors of the study in the U.S. journal Science.
