Researchers used NASA's Cassini spacecraft to identify 101 geysers erupting on Saturn's icy moon Enceladus.
The finding suggests water from the moon's underground ocean could potentially reach the surface, NASA reported. The findings are published in the current edition of the Astronomical Journal.
Over the past seven years Cassini's cameras have been trained on the south polar terrain of the moon; this region contains "tiger stripe" fractures. The geysers were spotted erupting from these fractures, their locations are believed to be consistent with small "hot spots."
The geysers were first seen in 2005; at this time scientists thought the flexing of the moon (as a result of its orbit) influenced the geyser's behavior. Some researchers thought back-and-forth rubbing of opposing walls of the fractures created heat that liquefied surrounding ice, causing a geyser. Another theory suggests the opening and closing of the fractures allowed water vapor to reach the surface.
The team looked at low-resolution maps of thermal emissions, and determined the greatest geyser activity coincided with the locations of highest temperature. These hotspots were too small to produce frictional heating, but the geysers could have been a result of water vapor on the near-surface walls of the fractures.
"Once we had these results in hand we knew right away heat was not causing the geysers, but vice versa," said Carolyn Porco, leader of the Cassini imaging team from the Space Science Institute in Boulder, Colorado, and lead author of the first paper. "It also told us the geysers are not a near-surface phenomenon, but have much deeper roots."
The researchers concluded the only plausible source of liquid was the ocean known to exist below the moon's icy shell. The team found narrow pathways leading from the underground ocean to the moon's surface can remain open if consistently filled with liquid water.
