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Saturn's Titan --Does it Hold Clues to 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," says Dr Hunter Waite, Southwest Research Institute, Space Science and Engineering Division and a 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 been verified on 16 different encounters.

“Cassini’s electron spectrometer has enabled us to detect negative ions which have 10,000 times the mass of hydrogen," said Andrew Coates, researcher at University College London’s Mullard Space Science Laboratory. "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.

The Daily Galaxy via University College London

Image credit: With thanks to


"[T]he atmosphere [of Titan] is full of nitrogen and methane, and resembles that of the early Earth." So what process changed Earth's atmosphere to breathable air to support advanced life? What was the causative mechanism?

@ John Umana- life made the atmosphere breathable. Our atmosphere is still mostly nitrogen. Photosynthetic bacteria are what wound up producing the oxygen in the atmosphere. Prior to about a billion years ago IIRC all surface life was anaerobic and oxygen was poison. I'm uncertain as to whether oxygen was poisonous to ocean bacteria, but believe it was.

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