Saturn's Titan Provides Insight into the Origin of Life in the Solar System

“Tholins are very large, complex, organic molecules thought to include chemical precursors to life. Understanding how they form could provide valuable insight into the origin of life in the solar system."

~ Dr Hunter Waite, Southwest Research Institute, Space Science and Engineering Division and leader of the ESA's Cassini’s Ion Spectrometer team

Saturn's moon Titan is the second largest in the solar system and the only one with a dense atmosphere. Cloaked in a thick orange haze, Titan’s secrets have been difficult to penetrate. But scientists now know that the atmosphere is full of nitrogen and methane, and resembles that of the early Earth.

Scientists analyzing data gathered by the Cassini spacecraft have confirmed the presence of heavy negative ions in the upper regions of Titan’s atmosphere. These particles are believed to act as organic building blocks for even more complicated molecules, which is an exciting indication that life on Titan is theoretically possible. This discovery was completely unexpected because of the chemical composition of the atmosphere, which lacks oxygen and mainly consists of nitrogen and methane. The observation has now been verified on 16 different encounters and findings will be published in Geophysical Research Letters on November 28.

Professor Andrew Coates, researcher at University College London’s Mullard Space Science Laboratory said, “Cassini’s electron spectrometer has enabled us to detect negative ions which have 10,000 times the mass of hydrogen. Additional rings of carbon can build up on these ions, forming molecules called polycyclic aromatic hydrocarbons, which may act as a basis for the earliest forms of life.

“Their existence poses questions about the processes involved in atmospheric chemistry and aerosol formation and we now think it most likely that these negative ions form in the upper atmosphere before moving closer to the surface, where they probably form the mist which shrouds the planet and which has hidden its secrets from us in the past. It was this mist which stopped the Voyager mission from examining Titan more closely in 1980 and was one of the reasons that Cassini was launched.”

So, scientists have now discovered that Titan has essential ingredients for life, but what are the chances that life has indeed formed? That’s a tricky question for scientists because we Earthlings only have our own planet’s life forms to postulate from. However, extremophiles living on our planet that are able to survive without sunlight while living in extremely cold temperatures, indicates that environmental conditions don’t always have to fall within an “ideal” range in order to support some forms of life.

Posted by Rebecca Sato

*This post is an adaptation of a University College London news release.