A Jet Propulsion Laboratory-managed spacecraft orbiting Saturn has discovered sub-surface emissions of potentially life-feeding hydrogen on one of the planet's moons, a finding billed Thursday as the closest NASA has come to identifying a possibly habitable world other than our own.
According to NASA and JPL, the Cassini spacecraft detected a flow of hydrogen gas into the sub-surface ocean on the icy moon Enceladus. Such emissions are seen as a key factor that likely spurred the development of life on Earth, because the gas combines with the carbon dioxide in water to provide metabolic energy.
"This is the closest we've come, so far, to identifying a place with some of the ingredients needed for a habitable environment," according to Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate.
According to NASA officials, life requires three basic ingredients -- liquid water; a source of energy for metabolism; and a combination of chemicals including carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur. The discovery of hydrogen plumes means Enceladus has almost all of those factors. Researchers are still trying to confirm the presence of phosphorus and sulfur on Enceladus, but they are confident it exists.
"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 JPL.
Although researchers have not actually found life on the planet, the hydrogen discovery proves there is a "food source" to support it.
NASA officials said Cassini detected the hydrogen during one of its final dives through a plume of material spraying from Enceladus in October 2015. Cassini discovered the spraying plume in 2005, about one year after the spacecraft arrived at Saturn.
Cassini is in the waning days of a mission that began 20 years ago. The spacecraft arrived at Saturn in 2004 and is running low on fuel. Project managers announced earlier this month that the craft will make a series of dives between Saturn and its famous rings beginning in late April. After it makes nearly two dozen such dives, the craft will crash into the planet's surface.