Well this is big: NASA has announced that its Cassini spacecraft, which orbits around Saturn, has confirmed the existence of molecular hydrogen in massive icy plumes of water and gas blasting out of the surface of Enceladus, one of the planet’s moons. Concurrently, NASA also says that the Hubble Space Telescope, which is in orbit around Earth, has found similar plumes being ejected from the surface of Europa, one of the moons orbiting Jupiter. NASA says these are significant findings with regards to answering the question “Is there life out there?” because they establish one of the crucial catalytic elements for life as we know it: a source of chemical energy.
Although Cassini is in orbit around Saturn, it has been able to do flybys fairly close to Enceladus’ surface. In 2015, Cassini made “its deepest dive ever through a plume of gas and ice spraying from the South Pole… of Enceladus,” and confirmed—to a very high degree of certainty—that there is indeed molecular hydrogen (H2) present in the plume. The molecular hydrogen was recorded by utilizing an Ion and Neutral Mass Spectrometer (INMS) instrument aboard Cassini, “which sniffs gases to determine their composition.”
The presence of molecular hydrogen, NASA notes, means that there is likely hydrothermal vents deep within Enceladus’ ocean—which covers the entire moon, and is under its icy crust. The existence of hydrothermal vents, which are “[openings] in the sea floor out of which heated mineral-rich water flows,” would be significant in terms of supporting life, because here on Earth, life can survive without sunlight if it evolves near the heat and energy of a hydrothermal vent. This would be critical for possible life on Enceladus as the moon is too far from the Sun for it to rely on sunlight for energy. Molecular hydrogen is also food for microbes, that “could use it to obtain energy by combining the hydrogen with carbon dioxide dissolved in the water” in a process known as “methanogenesis.”
At the same time, NASA also announced that the Hubble Space Telescope has observed water vapor plumes being ejected from the water-ice surface of Europa, which is thought to have a subsurface ocean like that of Enceladus (although it’s thought to be kept in motion and warmed up by tidal flexing, which is caused by the moon’s eccentric orbit around Jupiter). NASA notes that these vapor plumes “may be similar to what the Cassini spacecraft has seen at… Enceladus, where there are also water vapor plumes associated with warm regions of the moon’s surface.”
In their announcement, one NASA engineer noted that he is “optimistic” that Cassini’s findings are accurate and that this “sniffing out” of molecular hydrogen amongst the vapor plume marks one of the most significant discoveries for the spacecraft and scientific instrument, which arrived at Saturn in 2004, and is set to self-destruct soon when it dives into Saturn’s atmosphere on September 15 of this year.
As for further details and “sniffs” of the plumes spraying from the surface of Europa, NASA has a mission set for the 2020s that revolves around a spacecraft and scientific tool dubbed the Europa Clipper. The Europa Clipper will “make similar measurements to Hubble’s, but from thousands of times closer,” and also have “an exquisitely sensitive, next-generation version” of the sniffer used aboard Cassini. Jim Green, Director of Planetary Science at NASA says that “If there are plumes on Europa, as we now strongly suspect, with the Europa Clipper we will be ready for them.” But the real question is: Will we be ready for whatever we find in these heated, subsurface oceans? (The answer is yes, let’s do it!)
What do you think about these new “Ocean World” findings? Spray out your thought plumes into the comments space below!