How life may find a way on Saturn's moon

How life may find a way on Saturn's moon
Posted at 7:27 PM, Jul 28, 2017
and last updated 2017-07-28 20:27:47-04

It may not be like the alien life in science fiction, but researchers have just confirmed the presence of something that may lead to life on Titan, Saturn's largest moon, according to a study published Friday in the journal Science Advances.

Vinyl cyanide is a complex organic molecule capable of forming cell membrane-like spheres. While it may sound toxic, this chemical would be right at home on Titan, where significant quantities of it have been detected through data from the Atacama Large Millimeter Array, a group of radio telescopes in Chile.

Titan isn't exactly known for being hospitable.

Larger than both our own moon and the planet Mercury, Titan is unique in our solar system. It is the only moon with clouds and a dense atmosphere of nitrogen and methane, which gives it a fuzzy orange appearance.

Its atmospheric pressure is 60% greater than Earth's, meaning it exerts the kind of pressure you feel at the bottom of a swimming pool, according to NASA.

So it would make sense that the potential for life on Titan would have to look a little different. But Titan's atmosphere may not be much different than that of primordial Earth's -- and life found a way here.

Titan also has Earth-like liquid bodies on its surface, but the rivers, lakes and seas are made of liquid ethane and methane, which form clouds and cause liquid gas to rain from the sky.

The surface temperature is so cold -- minus 290 degrees Fahrenheit -- that the rivers and lakes were carved out by methane, the way rocks and lava helped to form features and channels on Earth.

These methane pools on the surface are the kind of environment that could help vinyl cyanide molecules link together to form cell-like membranes, not unlike the basis for organisms on Earth.

"The presence of vinyl cyanide in an environment with liquid methane suggests the intriguing possibility of chemical processes that are analogous to those important for life on Earth," said Maureen Palmer, lead study author and researcher at NASA's Goddard Space Flight Center.

The ALMA data confirmed what previous studies and simulations, like one from Cornell University in 2015, had predicted about the potential presence of this molecule on Titan.

"Researchers definitively discovered the molecule, vinyl cyanide, that is our best candidate for a 'protocell' that might be stable and flexible in liquid methane," said Jonathan Lunine, a Cornell professor who participated in the 2015 study. "This is a step forward in understanding whether Titan's methane seas might host an exotic form of life."

Titan is also believed to have an internal liquid water ocean, like those on Europa, one of Jupiter's moons, and Enceladus, another of Saturn's moons. Earlier this year, NASA announced that Europa and Enceladus' oceans have some or most of the ingredients necessary for life as we know it.

But how does Titan compare? First of all, it's bigger than Europa and Enceladus. It's also entirely unique in its possession of a dense atmosphere, which has obscured the observations that researchers have tried to make of Titan. And Titan doesn't have confirmed active geysers on its surface.

Given its complex chemistry, it's safe to say that Titan isn't hospitable to humans. But it is attractive to researchers.

NASA's Cassini spacecraft mission to Saturn comes to an end later this year, but proposed mission concepts already exist for a type of "Titan airplane" called the AVIATR (Aerial Vehicle for In-situ and Airborne Titan Reconnaissance) and a submarine that would explore Titan's seas.

"Saturn's moon, Enceladus, is the place to search for life like us, life that depends on -- and exists in -- liquid water," Lunine said. "Titan, on the other hand, is the place to go to seek the outer limits of life -- can some exotic type of life begin and evolve in a truly alien environment, that of liquid methane?"