In the fall of 2016, NASA’s Cassini spacecraft, which has been exploring Saturn since 2004, got closer than ever to an extraterrestrial ocean on Enceladus, which is one of the planet’s 62 moons. During its daring dive into an icy plume erupting from the moon’s south pole, Cassini sampled the spray to figure out what’s lurking beneath the surface.
“Enceladus is not just an ocean world. It’s a world that might provide a habitable environment for life as we know it,” Cassini program scientist Curt Niebur said at that time.
But even if the ocean material is full of little lifeforms, Cassini or any of us won’t know it. The spacecraft wasn’t built to actually detect life. Its instruments don’t have the ability to parse out sure signs, like DNA, from the icy spray.
Instead, scientists are hoping to learn more about the pH balance and molecular composition of the water. NASA is still analyzing the data from that October flyby. In the best-case scenario, the spacecraft might be able to determine if the small moon’s ocean could be habitable.
Cassini’s mission will end when it runs out of fuel sometime this year, 2017. Until then, the probe will be making its final observations of many of Saturn’s moons.
But is possible for life on Saturn’s Moon?
With a diameter of just 310 miles Enceladus is nevertheless the sixth largest of Saturn’s more than 60 moons, orbiting at a distance of just two planet-widths. Cassini has shown that Enceladus is the source of huge geysers of neutral water-rich gas and ice grains erupting at a rate of 220-660 lbs per second. This makes Enceladus the second most active object, after Jupiter’s moon Io which ejects 2200 lbs per second of sulphur-rich material.
Gravity measurements have shown that there is at least a local and possibly a global ocean under Enceladus’ icy crust, and some of the emitted grains are rich in sodium salt, which indicates the presence of a salty ocean. Now we also discover that some are silicate-rich, and analysis shows that these may have been produced close to hydrothermal vents at temperatures above 194°F. This raises the interesting comparison with hydrothermal vents on Earth, which may have played a role in the origin of life on our planet.
For life as we know it to exist, four key ingredients are important: liquid water; the right chemistry involving the elements carbon, hydrogen, nitrogen, oxygen, phosphorus and sulphur; a source of heat; and enough time for life to develop. While we know these conditions exist on Earth, planetary research throughout the solar system shows that it may exist on other objects too, and the details from research pushes Enceladus towards the top of the list.
Image source and Reference: Discover Magazine
