More signs of life spotted on Saturnian moon Enceladus
Few bodies in the solar system capture the imagination of life-hunting astronomers like the Saturnian moon Enceladus. Conveniently, hydrothermal vents pull materials from the moon’s core, mix them through its massive subsurface ocean and eject them into space, providing those searching for signs of life with plenty of subject matter. Scientists have discovered a couple of new organic compounds hiding within these icy plumes, shedding yet more light on the microbe-harboring potential of Saturn’s sixth-largest moon.
These plumes that carry ice and vapor into space have been the source of real intrigue for some time, and especially so since the Cassini probe plunged through the thick of them in 2015. The data the NASA probe gathered during this maneuver gave scientists plenty of new information to work with, uncovering evidence of complex organic molecules and conditions researchers described as “a candy store for microbes.”
Cassini met its demise in September 2017, but analysis of the data it collected continues apace. Scientists led by Nozair Khawaja from the Free University of Berlin pulled data from the spacecraft’s Cosmic Dust Analyzer and set out to study the makeup of organic material within the icy grains that had been ejected onto Saturn’s E ring, the second outermost of Saturn's rings.
In doing so, the team came across two organic compounds it hadn’t seen before. The compounds were found to bear nitrogen and oxygen and to have first dissolved into the moon’s subsurface ocean. From there, the scientists believe, the organic molecules then evaporated from the ocean surface, condensed into icy grains within fractures in the moon’s crust and were then blown into space by its plumes.
This chain of events is interesting to the researchers, as they believe it resembles a similar process that gives rise to life on Earth. Here, similar molecules are part of key chemical reactions where deep thermal ocean vents help form hydrogen and amino acids by interacting with surrounding rock and heated water.
The discovery of these two new organic compounds doesn’t offer conclusive proof one way or the other, but does add further weight to the theory that a similar process could be at play on Enceladus, and expands its growing list of ingredients that are necessary for life.
"If the conditions are right, these molecules coming from the deep ocean of Enceladus could be on the same reaction pathway as we see here on Earth," says Khawaja. "We don't yet know if amino acids are needed for life beyond Earth, but finding the molecules that form amino acids is an important piece of the puzzle."
The researchers published their study in the journal the Monthly Notices of the Royal Astronomical Society.