NASA discovers ‘weird’ molecule in Titan’s atmosphere that ‘could form life’

NASA scientists have found a "weird" molecule on Saturn's largest moon which they say could "form or feed possible life".

Researchers have discovered the presence of cyclopropenylidene, or C3H2, on Titan by using a radio telescope observatory in northern Chile known as the Atacama Large Millimeter/submillimeter Array (ALMA).

They noticed C3H2, which is made of carbon and hydrogen, while sifting through a spectrum of unique light signatures collected by the telescope which revealed the chemical makeup of Titan’s atmosphere by the energy its molecules emitted or absorbed.

Though scientists have found C3H2 in pockets throughout the galaxy, they say that finding it in an atmosphere was a surprise because cyclopropenylidene can react easily with other molecules it comes into contact with and form different species.

Astronomers have so far found C3H2 only in clouds of gas and dust that float between star systems — in other words, regions too cold and diffuse to facilitate many chemical reactions.

“When I realised I was looking at cyclopropenylidene, my first thought was, ‘Well, this is really unexpected,’” said Conor Nixon, a planetary scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who led the ALMA search.

His team’s findings were published on October 15 in the Astronomical Journal.

Scientists don’t yet know why cyclopropenylidene would show up in Titan’s atmosphere but no other atmosphere. “Titan is unique in our solar system,” Nixon said. “It has proved to be a treasure trove of new molecules.”

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Titan’s atmosphere is made mostly of nitrogen, like Earth’s, with a hint of methane.

When methane and nitrogen molecules break apart under the glare of the Sun, their component atoms unleash a complex web of organic chemistry that has captivated scientists and thrust this moon to the top of the list of the most important targets in NASA’s search for present or past life in the solar system.

“We’re trying to figure out if Titan is habitable,” said Rosaly Lopes, a senior research scientist and Titan expert at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California.

“So we want to know what compounds from the atmosphere get to the surface, and then, whether that material can get through the ice crust to the ocean below, because we think the ocean is where the habitable conditions are.”

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The types of molecules that might be sitting on Titan’s surface could be the same ones that formed the building blocks of life on Earth.

Early in its history, 3.8 to 2.5 billion years ago, when methane filled Earth’s air instead of oxygen, conditions here could have been similar to those on Titan today, scientists suspect.

“We think of Titan as a real-life laboratory where we can see similar chemistry to that of ancient Earth when life was taking hold here,” said Melissa Trainer, a NASA Goddard astrobiologist.

Cyclopropenylidene is the only other “cyclic,” or closed-loop, molecule besides benzene to have been found in Titan’s atmosphere so far.

Although C3H2 is not known to be used in modern-day biological reactions, closed-loop molecules like it are important because they form the backbone rings for the nucleobases of DNA, the complex chemical structure that carries the genetic code of life, and RNA, another critical compound for life’s functions.

“The cyclic nature of them opens up this extra branch of chemistry that allows you to build these biologically important molecules,” said Alexander Thelen, another Goddard astrobiologist.

JPL planetary scientist Michael Malaska said: “It’s a very weird little molecule, so it’s not going be the kind you learn about in high school chemistry or even undergraduate chemistry.

“Down here on Earth, it’s not going be something you’re going to encounter.”

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