Organic compounds have been found coming from Saturn's moon Enceladus, NASA has said. The discovery, researchers believe, is another "green light" for the potential for life to exist on this icy world.
On Earth, these compounds serve as the building blocks for life. If the same processes are happening on Enceladus, it could mean life exists there too.
The compounds were found in data from Cassini—the mission to Saturn that ended in September 2017 when the spacecraft plunged into the planet's atmosphere. But before its fiery death, Cassini performed three final flybys of Enceladus, during which it went through a plume coming from the moon.
In analyzing the data returned, researchers from the U.S. and Germany have now identified molecules on grains of ice in the plume, showing them to be nitrogen and oxygen-bearing compounds. On Earth, these compounds are involved in the production of amino acids—the building blocks of life.
The plumes coming from Enceladus are the result of hydrothermal vents sending material from the moon's core into space. It is thought that, between its icy outer shell and rocky core, Enceladus has a vast ocean of water—making it one of the more promising targets in the search for alien life within our solar system.
On Earth, hydrothermal vents on the seafloor are teeming with life. Many scientists think they may have been responsible for the first life on Earth, with chemical reactions producing the building blocks from which all organisms developed.
If the same reactions are taking place at the hydrothermal vents on Enceladus, it could mean life has also developed.
In their study, published in the Monthly Notices of the Royal Astronomical Society, researchers explain how they analyzed material collected from Enceladus' plume, finding compositional characteristics of organic compounds. They said these compounds are dissolved in Enceladus' subsurface ocean, before evaporating and freezing to the grains of ice in the moon's crust.
"If the conditions are right, these molecules coming from the deep ocean of Enceladus could be on the same reaction pathway as we see here on Earth," study leader Nozair Khawaja, from the Free University of Berlin, said in a statement. "We don't yet know if amino acids are needed for life beyond Earth, but finding the molecules that form amino acids is an important piece of the puzzle."
Co-author Frank Postberg added: "This work shows that Enceladus' ocean has reactive building blocks in abundance, and it's another green light in the investigation of the habitability of Enceladus."
