Strange molecules found by scientists in Titan’s atmosphere suggest complex chemical reactions

NASA scientists have discovered a “strange” molecule in the atmosphere of Saturn’s moon Titan called cyclopropyl. This simple carbon-based molecule, which has never been seen in the atmosphere before, may produce more complex compounds and help create the conditions needed for life.

Strange molecules found by scientists in Titan's atmosphere suggest complex chemical reactions

Titan is one of the most fascinating places in the solar system. It is the only world we know except Earth that has a stable liquid on its surface, forming lakes, rivers and oceans — but not water, but liquid methane and ethane. This causes its weather cycle to be very similar to Earth’s, with evaporation, rain, erosion, organic dust storms and tectonic activity shaping its landscape.

Now, astronomers have discovered a strange new feature of Titan. Using the Atakama Large Millimeter Wave/Sub millimeter Wave Array (ALMA), scientists observed the satellite’s spectrum and gained insight into the chemical composition of its atmosphere by studying the wavelengths emitted or absorbed by the molecules there.

In two separate sets of data, the team identified a strange “fingerprint”, the fingerprint of the acrylic sub-base. Its existence is surprising — it’s a very active molecule, so in a warm environment like Titan’s atmosphere, it should easily break down into other forms. As a result, cyclopropylene was previously detected only in interstellar dust clouds, where it is too cold for such chemical reactions to occur.

Strange molecules found by scientists in Titan's atmosphere suggest complex chemical reactions

Titan has been considered one of the most promising places to find extraterrestary life, thanks to its Earth-like dynamics, and this latest discovery offers new hope for this idea. So-called “closed-loop” molecules make up an important part of DNA and RNA skeletons, and although cyclopropylene is not known to play a role in these reactions, it is the simplest and smallest “closed-loop” molecule ever found in any atmosphere. There may be strange chemical reactions in life on the moon that are at work, leading to non-water-based life.

“We’re trying to figure out if Titan is habitable,” said Rosaly Lopes, a Titan expert at NASA’s Jet Propulsion Laboratory (JPL). “So we wanted to know which compounds in the atmosphere would reach the surface, and then whether they could pass through the ice crust to the ocean below, because we thought the ocean was habitable.”

NASA plans to send an aircraft called the Dragonfly to Titan in 2034, where it will jump around looking for signs of past or present life. Eventually, it could even explore the depths of the alien ocean with a submarine.

The new study was published in the Astronomical Journal.