NASA believes that the most likely places to find life beyond Earth could be right next door — at least in space terms. They have new evidence to suggest that Jupiter's moon Europa and Saturn's moon Enceladus both contain vital requirements that would allow for alien life to survive. Enceladus particularly has almost all of the key ingredients for life as we know it.
Enceladus is a frozen ice world, but beneath the inhospitable surface, scientists believe that basic life could be thriving in warm underground seas. NASA's Cassini spacecraft detected an abundance of hydrogen and carbon dioxide in water plumes that rise to the surface through fractures in the surface of the planet.
In a report published in the journal Science, NASA state that the "only plausible" source for the hydrogen was chemical reactions between warm water and rocks on the ocean floor. If hydrogen is present on the planet, it can mix with carbon dioxide to form methane, which is consumed by microbes that inhabit the depths of our own oceans.
Professor Hunter Waite of Southwest Research Institute in San Antonio and Principal Investigator for Cassini’s Mass Spectrometer explained why this discovery is so important:
“Saturn’s moon Enceladus has an ice-covered ocean, and a plume of material erupts from cracks in the ice.”
“The plume contains chemical signatures of water-rock interaction between the ocean and a rocky core. We find that the most plausible source of this hydrogen is ongoing hydrothermal reactions of rock containing reduced minerals and organic materials."
“On the modern Earth, geochemically derived fuels such as hydrogen support thriving ecosystems even in the absence of sunlight.”
Cassini was launched in 2005 to explore Saturn and its moons, with scientists suspecting that liquid water could exist on Enceladus because of the extreme tidal forces from Saturn’s gravity. In 2015, scientists discovered that Enceladus wobbled as it orbited Saturn, leading scientists to conclude that the interior of the planet is water, not ice.
In the years since, researchers have been studying data sent back from the spacecraft to see if they could pick up any clues that would indicate life exists on the moon. If life is present, it would probably resemble single-celled tube-like extremophiles which have inhabited Earth for billions of years.
David Rothery, Professor of Planetary Geosciences at The Open University, said:
“At present, we know of only one genesis of life, the one that led to us."
“If we knew that life had started independently in two places in our Solar System, then we could be pretty confident that life also got started on some of the tens of billions of planets and moons around other stars in our galaxy.”
“This is life that needs neither oxygen nor sunlight, and may be the form in which life on Earth began, before some of it adapted to other conditions.”
Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate, added:
"This is the closest we've come, so far, to identifying a place with some of the ingredients needed for a habitable environment."
"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."