A tiny, ice-encrusted ocean world orbiting Saturn is now a hotter-than-ever candidate for potential life.
NASA's Cassini spacecraft has detected hydrogen molecules in the geysers shooting off the moon Enceladus, possibly the result of deep-sea chemical reactions between water and rock that could spark microbial life.
The findings were announced Thursday in the journal Science.
"This is the closest we've come, so far, to identifying a place with some of the ingredients needed for a habitable environment," said Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate at Headquarters in Washington. "These results demonstrate the interconnected nature of NASA's science missions that are getting us closer to answering whether we are indeed alone or not."
NASA and others are quick to point out this latest discovery does not mean there's life on Enceladus, but that there may be conditions favorable for life.
A liquid ocean exists beneath the icy surface of Enceladus, which is barely 300 miles (500 kilometers) across. Plumes of water vapor spew from cracks at the moon's south pole.
The ingredients scientists look for when it comes to the possibility of life as we know it are liquid water, a source of energy for metabolism and the chemicals carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur. So far, the Cassini mission has show nearly all those ingredients except phosphorus and sulfur in the ocean world.
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"Confirmation that the chemical energy for life exists within the ocean of a small moon of Saturn is an important milestone in our search for habitable worlds beyond Earth," said Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena.
The finding is a welcomed surprise for the Cassini mission, which wasn't launched with the intent of finding signs of worlds that could support life. The spacecraft detected chemicals in plumes of gas and ice that burst from Enceladus.
"Although we can't detect life, we've found that there's a food source there for it. It would be like a candy store for microbes," said Hunter Waite, lead author of the Cassini study.
Launched in 1997 and now finally running low on fuel, Cassini is drawing ever closer to its demise. The spacecraft will duck through the gap between Saturn and its rings 22 times before spiraling out of control and vaporizing in the sky above Saturn this September.
NBC4's Jonathan Lloyd contributed to this report.