Underground ocean on Titan, alien life on Phobos?

June 29, 2012

This artist's concept shows a possible scenario for the internal structure of Titan, as suggested by data from NASA's Cassini spacecraft (credit: A. Tavani/NASA)

Saturn’s moon Titan likely harbors a layer of liquid water under its ice shell in a hidden ocean at depth, data from NASA’s Cassini spacecraft have revealed.

The evidence is tidal, according to Luciano Iess, the paper’s lead author and a Cassini team member at the Sapienza University in Rome. Saturn’s powerful gravity stretches and deforms Titan as the moon moves around the gas giant planet. If Titan were composed entirely of stiff rock, the gravitational attraction of Saturn should cause bulges, or solid “tides,” on the moon only 3 feet (1 meter) in height.



Because Titan’s surface is mostly made of water ice, which is abundant in moons of the outer solar system, scientists believe Titan’s ocean is likely mostly liquid water.



The results have a bigger implication for the mystery of methane replenishment on Titan.  Methane is abundant in Titan’s atmosphere, yet researchers believe the methane is unstable, so there must be a supply to maintain its abundance.



Evidence of life on Mars from Martian moon


The image shows the orbits of the Martian moons Phobos and Deimos and the spread of potential particle trajectories from an asteroid impact on Mars (credit: Chappaz/Purdue University)

Meanwhile, a mission to Martian moon Phobos could return with alien life, experts at Purdue University have suggested.

“A sample from Phobos, which is much easier to reach than the Red Planet itself, would almost surely contain Martian material blasted off from large asteroid impacts,” said Jay Melosh, a distinguished professor of earth, atmospheric and planetary sciences and physics and aerospace engineering at Purdue.



A Phobos mission was discussed at NASA’s Concepts and Approaches for Mars Exploration workshop and a report issued Tuesday stated that the Martian moons are “important destinations that may provide much of the value of human surface exploration at reduced cost and risk.”








“It is estimated that during the past 10 million years there have been at least four large impact events powerful enough to launch material into space, and we focused on several large craters as possible points of origin,” he said. “It turns out that no matter where Phobos is in its orbit, it would have captured material from these powerful impact events.”


“It is not outside the realm of possibility that a sample could contain a dormant organism that might wake up when exposed to more favorable conditions on Earth,” he said. “I participated in a study that found that living microbes can survive launch from impacts on rock, and other studies have shown some microscopic organisms can tolerate a lot of cosmic radiation.”

This possibility has been a consideration for some time, and Michael Crichton’s “The Andromeda Strain” brought it to public consciousness in 1969. However the movie scenario of a fatal contamination is unlikely, Melosh said.

“Approximately one ton of Martian material lands on Earth every year, ” he said. “There is a lot more swapping back and forth of material within our solar system than people realize. In fact, we may owe our existence to life on Mars.”

Howell also is optimistic that life is not unique to Earth.

“It’s difficult to believe there hasn’t been life somewhere out there in the vast expanse of space,” Howell said. “The question is if the timeline overlaps with ours enough for us to recognize it. Even if we found no evidence of life in a sample from Phobos, it would not be a definitive answer to the question of whether or not there was life on Mars. There still may have been life that existed too long ago for us to detect it.”

Melosh recently presented the team’s findings at a joint NASA and European Space Agency meeting in Austria, and Chappaz will present the data at a meeting on July 14 in Mysore, India.