Scientists Say Saturn Moon Like 'Early Earth'





9:36am UK, Tuesday August 11, 2009
Scientists believe they have located Earth's nearest likeness - circling Saturn as one of its moons.





Although it is millions of miles away from us, planet-sized Titan also has choking smog and flash floods - just like Earth.
"It really is surprising how closely Titan's surface resembles Earth's," said planetary geologist Rosaly Lopes, from Nasa's Jet Propulsion Laboratory (JPL), in California.
"In fact, Titan looks more like the Earth than any other body in the solar system, despite the huge differences in temperature and other environmental conditions."
Dr Lopes announced the news at a Titan presentation at the the International Astronomical Union Assembly in Rio de Janeiro, Brazil.
Scientists activated radar beams on Nasa's Cassini probe to see through the smoggy atmosphere and they have now mapped a third of Titan's surface.
Titan is one of the biggest moons in the solar system, larger than the planet Mercury and approaching Mars in size.
But despite an atmosphere hostile to humans, it is scattered with lakes, dunes, mountain ridges and possibly volcanoes.
Cassini has been probing Saturn and its moons for five years, as well as communicating with the European Space Agency's Huygens probe, which descended on Titan in 2005.

One exciting question is whether Titan's chemical processes today support a prebiotic chemistry similar to that under which life evolved on Earth?

Nasa's research senior scientist, Robert M Nelson



Titan has long-fascinated astronomers as the only moon known to possess a thick atmosphere, and as the only celestial body other than Earth to have stable pools of liquid on its surface.
Nasa had earlier, unfulfilled plans to use blimps to chart the Titanic territory.
The many lakes that pepper the northern polar latitudes, with a scattering appearing in the south as well, are thought to be filled with liquid hydrocarbons, such as methane and ethane.
"With an average surface temperature hovering around -180° Celsius, water cannot exist on Titan except as deep-frozen ice as strong as rock," Dr Lopes said.
Methane rain cuts channels and forms lakes on the surface and causes erosion, helping to erase the meteorite impact craters that pockmark most other rocky worlds, such as our Moon and on Mercury.


Other research presented at the conference points to volcanic activity on Titan, but instead of scorching hot lava, scientists think "cryovolcanoes" eject cold slurries of water-ice and ammonia.
"These new results are the next advance in this exploration process," Robert M Nelson, a senior JPL research scientist, said.
Although the chemical concoctions on Titan sound deadly, they were in fact essential ingredients for life on our own planet.
"It has not escaped our attention that ammonia, in association with methane and nitrogen, the principal species of Titan's atmosphere, closely replicates the environment at the time that life first emerged on Earth," Mr Nelson revealed.
"One exciting question is whether Titan's chemical processes today support a prebiotic chemistry similar to that under which life evolved on Earth?"