Life on Saturn moon? Discovery of hidden ocean on Titan tantalizes. (+video)
Scientists already knew Titan has the building blocks for organic life in abundance. Now, the discovery of a underground sea with liquid water adds another intriguing element.
A global ocean appears to lurk miles beneath the surface of Saturn's moon Titan, adding to the allure of an object rich with the building blocks of organic life and often likened to Earth before life emerged.
Cassini has already found large lakes – most likely made of hydrocarbons such as liquid methane – on Titan's surface. But a team of scientists using NASA's Cassini spacecraft have now found indirect but telltale signs of a subsurface sea, perhaps of water as well as ammonia, which would act like antifreeze.
The data suggest that the ocean, perhaps more than 15 miles deep, is sandwiched between two layers of ice, each less than 60 miles (100 kilometers) thick. It rides atop one layer of ice covering the moon's rocky core and appears to be capped with another ice layer that forms Titan's surface.
Titan has captured the imagination of scientists hunting for potential habitats for simple forms of life for decades. The temperature at Titan's surface is unbearably cold, minus 290 degrees Fahrenheit. It is paved with the methane ices and other organic solids on which Cassini's Huygens probe landed on Jan. 14, 2005. Its atmosphere is thought to mirror the composition of Earth's atmosphere before the emergence of life some 3.8 billion years ago.
As hostile as the surface seems to be, "liquids from below would enhance the possibility of life being on the surface" as well as enhancing the possibility of aquatic habitats deep beneath Titan's crust, says Dirk Schulze-Makuch, an astrobiologist at Washington State University in Pullman with a keen interest in Titan's potential habitability.
Thursday's report represents "a nice step forward" in establishing an ocean's presence on Titan, he says.
The new finding adds Titan to the growing list of moons thought to have subsurface oceans. The icy surface of Jupiter's Europa is believed to hide a vast ocean, and data from Cassini suggest a large, if not global, region of water or slush under the icy sheath of Saturn's Enceladus. Neptune's moon Triton may also have a subsurface ocean, and Ganymede and Callisto, two more Jovian moons, also are though to have under-ice seas.