Furthermore, also study published Thursday in the Astrophysical Journal Letters reveals that thanks to the US Hubble Space Telescope, scientists have observed in 2016 what appears to be a geyser a hundred kilometers high in Europe, one of the largest Jupiter's moons, which also has an ocean under a layer of ice.
The presence of ample hydrogen in the moon's ocean means that microbes - if any exist there - could use it to obtain energy by combining the hydrogen with carbon dioxide dissolved in the water.
There are three essential ingredients for life: water, a source of energy for metabolism, and a mixture of carbon, hydrogen, nitrogen, oxygen, phosphorus and sulphur. Now, the American space agency has announced that Saturn's moon Enceladus is a habitable world because it has almost all the ingredients to support life.
This hydrogen is now said to be 'a potential source of chemical energy that could support microbes on the seafloor of Enceladus, ' the researchers revealed during the news briefing.
The moon, which is about 300 miles across, has a subsurface liquid ocean similar to what is believed to exist on Europa, an ice-covered moon of Jupiter.
Earth's hydrothermal vents are thriving with microbial life - leading scientists to believe that the icy ocean world could be habitable.
"We're moving towards Enceladus's ocean being habitable, but we're not making any claims at this point about it being inhabited", lead author Hunter Waite of the Southwest Research Institute (SwRI) in San Antonio, Texas told Reuters. There, in addition to water, it was able to identify traces of methane, ammonia, carbon monoxide, carbon dioxide, simple organic molecules and salts.
Enceladus, which is 502 kilometres (312 miles) across, is one of numerous moons orbiting Saturn, the largest of which, Titan, is bigger than the planet Mercury.
"These results demonstrate the interconnected nature of Nasa's science missions that are getting us closer to answering whether we are indeed alone or not".
It means Enceladus may have the same single-celled organisms which began life on Earth, or more complex life still.
"This finding is an important step to assess the habitability of Enceladus", said in an article accompanying the study, Jeffrey Seewald, a scientist at the Woods Hole Oceanographic Institution.
Finding life or indeed living on other planets ourselves has always been a dream but, at the rate that we're going, it might soon become a critical necessity. The team suggests that this phenomenon is a chemical effect of interactions between the rocky core and warm water from the underground ocean of the moon. The warm region, considered a thermal anomaly on the icy Europa, close to the plume was seen in the late 1990s by the Galileo spacecraft.
As for Jupiter's moon Europa, the observation is less definitive and more remote, coming from the Hubble Space Telescope. Both studies are laying the foundation for the Europa Clipper mission, which is slated to launch in the 2020s.
"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.