Methane in the Martian atmosphere and organic chemicals in the red planet's soil are the latest tantalizing findings of NASA's Mars Curiosity rover as it hunts for clues about the possibility of extra-terrestrial life, scientists said on Tuesday (December 16).

NASA scientists said Curiosity found periodic bursts of methane, a gas that on Earth is strongly tied to life, in the atmosphere around its landing site in the red planet's Gale Crater.

The rover also has found organic chemicals in the Martian soil, the scientists said at a webcast press conference at the American Geophysical Union conference in San Francisco.