Researchers have discovered a deep saltwater ocean on one of the many small moons that orbit Saturn, (1) .............. scientists to conclude it is the most likely place in the solar system for extraterrestrial life to be (2) ...............

Gravitational field measurements taken by Nasa‘s Cassini space probe revealed that a 10kmdeep ocean of water lurks (3) .............. the icy surface of Enceladus at the moon‘s south pole.

David Stevenson, a planetary scientist at the California Institute of Technology in Pasadena, said the body of water was so large it «may (4) .............. halfway or more towards the equator in every direction».

The presence of a saltwater ocean a billion kilometres from Earth more than satisfies Nasa‘s long-held mantra of ―follow the water‖ to find signs of alien life, but water is not the only (5) .............. that makes Enceladus such a promising habitat

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