New Enceladus findings could have big implications in the search for alien life

Life as we know it requires liquid water, and until recently that seemed to be in short supply outside of Earth. However, recent studies of Mars and several moons have pointed to the presence of water. In fact, some moons may contain subsurface oceans with a larger total volume of water than Earth has. In the latest revelation, NASA announced strong evidence for life-sustaining conditions in the subsurface oceans of Saturn’s moon Enceladus.

Scientists have known that Enceladus harbors a liquid ocean under its surface since 2005. That’s when the Cassini probe spotted the now-famous water plumes erupting from the moon’s surface. The outer surface of Enceladus is a sheet of ice some 11-14 miles thick, but below that is water that escapes through cracks as the moon flexes from the tidal forces of Saturn’s gravity.

Cassini has flown through the plumes several times to sample to study the phenomenon. While the probe is nearing the end of its mission, NASA sent it through one more trip through the plumes in late 2015. The newly released results of that trip show the presence of molecular hydrogen (H₂) in Enceladus’ water.

The presence of hydrogen in the plume is a big deal. Scientists believe it’s being produced at hydrothermal vents similar to the ones on Earth. Hydrogen can be used as chemical energy for microorganisms, which combine it with carbon dioxide in a process called methanogenesis. The name comes from the byproduct — methane. And indeed, some methane was detected in the plume along with hydrogen and a lot of water. Methanogenesis is an important process on Earth, carried out by a type of microorganisms known as archaea. These are some of the heartiest life forms on Earth, so maybe something similar exists on Enceladus. We can’t know for sure, because all we have so far is an analysis of the material escaping into space.

It was lucky Cassini was even able to determine this much — the Ion and Neutral Mass Spectrometer (INMS) instrument used for this analysis was included to sample the atmosphere of Titan. That moon is interesting in its own right, but scientists were shocked to find the water plumes of Enceladus after Cassini arrived in orbit of Saturn. So, the INMS pulled double duty to test the water in those plumes.

Scientists have spotted similar plumes rising above Jupiter’s moon Europa. NASA is planning a mission for the 2020s called Europa Clipper that will be able to take a closer look at the interior of the moon. Data from the study of Enceladus will help scientists decide what instruments to send along with the probe. Now we know what to look for, so maybe we’ll get closer to confirming something is alive out there.