Does Titan's hydrocarbon soup hold a recipe for life?

February 1, 2018, Astrobio.net
This image shows Titan in ultraviolet and infrared wavelengths. Red and green colors indicate where atmospheric methane is absorbing light, while the blue color shows the upper atmospheric haze. Credit: NASA/JPL/Space Science Institute

NASA researchers have confirmed the existence in Titan's atmosphere of vinyl cyanide, which is an organic compound that could potentially provide the cellular membranes for microbial life to form in Titan's vast methane oceans. If true, it could prove to us that life can flourish without the ubiquitous H2O.

Earth-based cell membranes are made of phospholipids: molecular chains with phosphorus-oxygen heads and carbon-chain tails that bind to each other to form a flexible in water. Methane-based life, should it exist, would need an alternative to Earth's phospholipid-based existence and would open up a much wider range of planets and moons to the possibility of extraterrestrial life. one possible alternative is vinyl .

The Cassini spacecraft first inferred the presence of vinyl cyanide on the Saturnian moon through the use of its mass spectrometer, but it took the highly sensitive gaze of the Atacama Large Millimeter/submillimeter Array (ALMA), in the desert of Chile, to confirm vinyl cyanide is, indeed, there.

Maureen Palmer, a researcher at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and lead author of a paper describing the research in Science Advances, collected archival data from ALMA and saw vinyl cyanide high in Titan's atmosphere, at altitudes greater than 200 kilometers, with its highest concentrations in areas above Titan's southern pole.

In the low temperatures on Titan, which reach –179 degrees Celsius (-290 degrees Fahrenheit), organic molecules in the atmosphere form droplets that rain down to fill methane lakes in a weather cycle similar to that of Earth's water cycle. There, they could potentially create simple, microscopic life forms. Palmer's group performed modeling studies that showed there is enough vinyl cyanide in Ligeia Mare, Titan's northern lake, to form about 10 million cells per cubic centimeter, roughly 10 times more than the bacteria in Earth's coastal oceans.

Titan’s northernmost giant lake, Ligeia Mare, contains enough vinyl cyanide to form the cell membranes of ten million cells per cubic centimeter. Credit: NASA/JPL–Caltech/ASI/Cornell

Vinyl cyanide has yet to be proven to produce life, but an earlier study by Cornell University researchers that was also published in Science Advances made it an intriguing prospect. The Cornell researchers, led by Professor of Chemical and Biological Engineering Paulette Clancy, set out to discover whether molecules that exist on Titan could form cell membranes called azotosomes, which is the name given to cell membranes that might form in Titan's liquid methane conditions.

Phosphorus and oxygen, found in Earth cell membranes, don't exist in Titan's frigid methane oceans, so any cell-like membranes would have to be based on nitrogen, hydrogen and carbon, all of which are abundant on Titan. Molecular modeling studies of a variety of molecules containing these elements showed that vinyl cyanide was the molecule most likely to form a stable and flexible membrane that acts like Earth-based membranes under Titan's conditions.

Still, vinyl cyanide-based life, like any other, would face challenging circumstances on Titan. However, Palmer says that "if membranes can be made in a lab with a simulation of Titan's ocean conditions, it would make us more optimistic about them really forming on Titan."

She notes further that because of its extensive atmospheric chemistry, and its bodies of surface liquid, Titan is "an interesting chemical laboratory to study the boundaries of possible biochemistry for creating life."

Clancy says that Palmer's lab findings were "an exciting validation of our prediction, since they also find that the concentration of vinyl cyanide is considerable enough to make self-assembly into azotosome-like vesicles a viable process."

She adds, "It also shows the power of molecular simulation to shine a flashlight onto the most promising candidates for prebiotic in conditions that are difficult to emulate in the lab."

Explore further: Scientists find moon of Saturn has chemical that could form 'membranes'

Related Stories

Cassini's search for the building blocks of life on Titan

September 13, 2017

Lakes and seas of liquid methane, rain from hydrocarbon clouds, and evidence of poisonous hydrogen cyanide in the atmosphere of Titan were just some of the discoveries the Cassini probe made of Saturns's largest moon.

Cyanide ice in Titan's atmosphere

October 1, 2014

Gigantic polar clouds of hydrogen cyanide roughly four times the area of the UK are part of the impressive atmospheric diversity of Titan, the largest moon of Saturn, a new study led by Leiden Observatory, the Netherlands ...

Recommended for you

Calibrating cosmic mile markers

December 11, 2018

New work from the Carnegie Supernova Project provides the best-yet calibrations for using type Ia supernovae to measure cosmic distances, which has implications for our understanding of how fast the universe is expanding ...

Team finds evidence for carbon-rich surface on Ceres

December 10, 2018

A team led by Southwest Research Institute has concluded that the surface of dwarf planet Ceres is rich in organic matter. Data from NASA's Dawn spacecraft indicate that Ceres's surface may contain several times the concentration ...

2 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

rrwillsj
1 / 5 (2) Feb 01, 2018
I do not approve of how this research line is being touted as a method to discover what we, here on Earth, recognize as biology.

Otherwise, if there was a biology on Titan? After billions of years? Wouldn't there be some visible evidence of it altering Titan's surface to a more hospitable environment? As occurred over the last several billion years to the Earth?

All that is visible of Titan's surface are the raw materials for what may eventually become native life.

Though I'm sure we won't give indigenous pre-life any time to evolve. Exterminate as we contaminate the moon with Earth organisms.
TheGhostofOtto1923
not rated yet Feb 05, 2018
I do not approve of how this research line is being touted as a method to discover what we, here on Earth, recognize as biology
Lots of people here dont approve of ignorant trolls and pissants who take cheap shots at the hard work of genuine scientists, simply because theyre too dim to understand it.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.