From these observations scientists have determined that almost 98 percent of the gas in the plume is water, about 1 percent is hydrogen and the rest is a mixture of other molecules, including carbon dioxide, methane and ammonia. Such emissions are seen as a key factor that likely spurred the development of life on Earth, because the gas combines with the carbon dioxide in water to provide metabolic energy.
The others? Carbon, nitrogen, oxygen, phosphorus and sulfur in an environment with liquid water and an energy source. This doesn't mean that there is life on Enceladus, but it is possible that some form of life exists there.
While it's not expected that NASA will announce any concrete evidence for extraterrestrial life, the agency has promised to reveal new information about our solar system's ocean worlds collected by the Hubble and soon-to-be-departed Cassini spacecrafts.
Writing in the journal Science, the USA team led by Dr Hunter Waite, from the Southwest Research Institute in San Antonio, Texas, concluded: "Our analysis supports the feasibility of methanogenesis as an energy-releasing process that can occur over a wide range of geochemical conditions plausible for Enceladus' ocean".
During Cassini's close flyby of Enceladus on October 28, 2015, INMS detected molecular hydrogen as the spacecraft flew through the plume of gas and ice grains spewing from cracks on the surface. The Cassini spacecraft wasn't created to detect life in Enceladus plume since the scientists didn't know that it existed until the spacecraft reached Saturn.
Like Jupiter's moon Europa, Enceladus is believed to be surrounded by a global watery ocean covered by thick ice.
"We now know that Enceladus has nearly all of the ingredients that you would need to support life as we know it on Earth", she said at a NASA news conference.
The team says the moon has the sources needed for life, but what needs to be established is if it has enough time to evolve life.
"Most of us would be excited with any life", said Mary Voytek, an astrobiology senior scientist for NASA. "The plumes on Enceladus are associated with hotter regions, so after Hubble imaged this new plume-like feature on Europa, we looked at that location on the Galileo thermal map".
NASA is planning for a new mission known as the Europa Clipper mission, which is now slated for the early 2020s. "We re finding new environments", said James Green, NASA s Planetary Science Division Director.