The elusive and enigmatic plumes of water vapor from the moon Jupiter in Europe look really real.
NASA's Hubble Space Telescope has detected indirect evidence of such feathers emanating from Europewhich is thought to house a huge and salty ocean under its ice shell. And researchers have now detected water vapor from one of these feathers directly for the first time, according to a new study.
"Essential chemical elements (carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur) and energy sources, two of the three requirements for life, are found all over the world. the solar system. But the third – liquid water – is a little difficult to find beyond Earth, "said study author Lucas Paganini, planetary scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and American University in Washington, DC, in statement.
"Although scientists have not yet detected liquid water directly, we have found the next best thing: steam-shaped water," added Paganini.
Related: Possible water feathers in Europe: the discovery in images
Paganini and his colleagues used the W.M. Keck Observatory in Hawaii to study Europe, 3,100 kilometers wide, which astrobiologists consider one of the countries in the solar system. best bets to host alien life.
The researchers observed Europe for 17 nights from February 2016 to May 2017. On one of these nights – April 26, 2016 – they received a strong water vapor signal in the form of a characteristic wavelength of emitted infrared light.
And there was a little of that – about 2,300 tons (2,095 tons), according to the researchers' calculations. That is almost enough to fill an Olympic-size pool (which contains about 2,750 tons or 2,500 metric tons of water).
Researchers think the source of this water is a feather, which may come from the buried ocean or from a reservoir of melted ice within the shell of Europe. For starters, the observed volume is much larger than expected to result from "exogenous" processes such as the removal of water molecules from the surface of Europe by Jupiter's powerful radiation belts. And this removal would probably occur fairly regularly, or at least often enough to be noticed more than one night in 17, Paganini and his team wrote in the new article, which was published online today (November 18) in the journal Nature Astronomy.
Several lines of evidence now point to the existence of feathers in Europe. For example, in addition to new findings and Hubble's detection of atomic hydrogen and oxygen (which presumably came from radiation-separated water molecules), NASA's Galileo Jupiter spacecraft measured a large increase in the density of plasma, or ionized gas, during a European flyover in 1997.
And it is becoming increasingly clear that Europe's feathers are sporadic. In this respect they are very different from the constant plume that floats on the south pole of Saturn's icy oceanic moon Enceladus, which is generated by over 100 powerful geysers that are always on.
"For me, the interesting thing about this work is not only the first direct detection of water above Europe, but also the lack of it within the limits of our detection method," said Paganini.
Feathers such as those emanating from Enceladus and Europa are very exciting for astrobiologists, because they are sending "free samples" of potentially habitable environments into space for possible robotic probe runs over. And there is a possibility that a NASA spacecraft will soon do just that, if all goes well.
NASA is developing a mission called Clipper Europe, which is scheduled to launch in the mid-2020s. Clipper will orbit Jupiter, but will closely study Europe on dozens of flybys, characterizing the moon and its ocean and looking for locations where a potential potential landing operator might land in the future. . Clipper may end up extending the plumage of one or more of these flybys if mission team members learn enough about the feature in the coming years – or if they are very lucky.
Mike Wall's book on the search for alien life "Out there"(Grand Central Publishing, 2018; illustrated by Karl Tate), left now. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook.