In the paper, the Cassini scientists shared that Enceladus has a type of chemical energy, which life can feed on. It's looking more and more like the most habitable spot in our solar system beyond Earth, and scientists' best target yet in the search for alien organisms. The area also corresponds to a warm region on Europa's surface. Hollywood explored this terrain in the 2013 film Europa Report, depicting a crewed mission to the moon and investigation of its subsurface ocean.
"If there are plumes on Europa, as we now strongly suspect, with the Europa Clipper we will be ready for them", said Jim Green, Director of Planetary Science, at NASA Headquarters.
"We're pushing the frontiers".
Analysis has shown the plumes mainly to consist of tiny particles of water ice, with traces of methane, ammonia, carbon dioxide, salts, and simple organic molecules. Data from the Cassini spacecraft already have indicated that Saturn's moon Enceladus has an ocean that spews into space through cracks in its icy crust.
In a subsequent flyby through the plume in 2015, Cassini's INMS was programmed into a mode that helped to minimize any analytical artifacts that had previously compromised the measurements of the energy source, molecular hydrogen. That's where it gets interesting: Cassini has shown Enceladus to comprise all of these, to be exception of the latter two.
The presence of hydrogen could also indicate the presence of microbes, which could use it to obtain energy by combining it with the carbon-di-oxide dissolved in the water. Have you ever wondered if there is life beyond the Earth?
"It really represents a capstone finding for the mission", Cassini project scientist Linda Spilker said. "Because we now know that Enceladus has nearly all of the ingredients you would need to support life as we know it on Earth". This chemical reaction, known as "methanogenesis" because it produces methane as a byproduct, is key to forming life.More news: 'Doctor Who' Spinoff 'Class' Is in Session at BBC America
The new findings are an independent line of evidence that hydrothermal activity is taking place in the Enceladus ocean.
"This exposes rocks to warm water, which drives geochemical transformations", he said.
Jeffrey Seewald of the Woods Hole Oceanographic Institution echoed those comments in a companion article to the study: "This observation has fundamental implications for the possibility of life on Enceladus".
"[The] fact that that we can measure such high concentrations of hydrogen and carbon dioxide mean that there might not be life there at all, and if there is life, it's not very active". Enceladus is the only one of Saturn's moons where scientists have found proof of an energy source for life. The next mission to Jupiter's moon may find a habitable environment.
Cassini is on what NASA has described as its "grand finale" as it runs low on fuel, soaring through a 1,500-mile-wide (2,400-kilometer) gap between Saturn and its rings. Then the Galileo mission reached Europa in 1996 and revealed for the first time that there was an ocean on another planet. They spotted water plumes rising 125 miles above the surface in September using the Hubble Telescope.
Enceladus's south polar plumes, as seen by Cassini November 30 2010. But its detectors were turned towards Jupiter's icy moon Enceladus post discovering the emission of the towering plume of icy spray in 2015. But just past year, they observed yet another, higher plume, and in the exact same location as the 2014 plume.