A new study has revealed that Enceladus, one of Saturn’s moons, has phosphorus in its ocean, a key element for life as we know it. The discovery was made by analysing data from NASA’s Cassini spacecraft, which explored the Saturn system from 2004 to 2017.
Phosphorus is essential for the structure of DNA, the function of cell membranes and the storage of energy in living organisms. It is also the rarest of the six elements that are considered necessary for life, along with carbon, hydrogen, oxygen, nitrogen and sulphur.
The researchers found phosphorus in ice grains that were ejected into space by geysers erupting from Enceladus’s sub-surface ocean. The ocean lies beneath a thick layer of ice and is heated by tidal forces from Saturn. The geysers also feed Saturn’s E ring, a faint ring of icy particles that surrounds the planet.
The study, published in the journal Nature, estimated that the concentration of phosphorus on Enceladus is at least 100 times higher than that of Earth’s oceans. This suggests that the ocean has a rich chemistry that could support life, or at least its formation.
Enceladus is one of the most promising candidates for finding extra-terrestrial life in our solar system. It has previously been shown to have organic compounds, amino acids and other ingredients for life in its ocean. However, phosphorus was the missing piece of the puzzle until now.
The study’s lead author, Frank Postberg, a planetary scientist at the Free University in Berlin, said that the discovery of phosphorus on Enceladus was “the first time this essential element has been found in an ocean beyond Earth”. He added that it makes Enceladus "a prime candidate for places beyond Earth that could be habitable".
