A group of Nasa researchers have attempted to replicate the atmospheric chemistry of Saturn's largest moon, Titan, and discovered that it could contain nucleotides -- the building blocks of life.

Sarah Hörst from the University of Arizona led the research, which was inspired by the discovery of large, but unidentified, molecules in Titan's atmosphere by the Cassini probe. "We wanted to find out what they could be," she said.

So her team whipped up a mix of carbon monoxide, molecular nitrogen and methane that are known to exist in the moon's thick, smoggy atmosphere, and blasted it with radiation to simulate light from the Sun. What emerged surprised the team -- a selection of complex molecules, including amino acids and the five nucleotide bases -- the ingredients of DNA and RNA.

"When I pressed the enter key, I expected a big 'nope, not there'," Hörst said. "Our experiment is the first proof that you can make the precursors for life up in an atmosphere, without any liquid water."

She added: "We had about 5,000 molecules containing the right stuff: carbon, nitrogen, hydrogen, and oxygen. We knew we had the elements for organic molecules, but we couldn't tell how they were arranged. It's kind of like Lego -- the more there are, the more possible structures can be made. And they can be put together in many different ways."

Titan doesn't have a whole lot of oxygen around to form carbon monoxide, and what it does have isn't generated on the moon itself. Instead, Cassini witnessed plumes of water being shot into space from geysers on Titan's sister moon, Enceladus. In space, that water is broken up into hydrogen and oxygen by energetic particles or solar radiation, and the gases are then pulled into Titan's atmosphere by the flow of Saturn's magnetic field.

The presence of methane in the atmosphere is a bit of a mystery, however. Energy from the Sun should have converted all of Titan's methane into complex hydrocarbons within about 50 million years -- a relatively short amount of time in the life of the solar system. The fact it's still there suggests that it's being replenished by something -- either cryovolcanic eruptions beneath the thick atmosphere, or from some form of life at the surface.

Hörst's discovery supports the latter theory, but it's still far from confirmed, and there's much work to do. "We still don't know for sure what the actual molecules are in Titan's atmosphere," she says, "but there's a distinct possibility that life's precursors are raining down on the surface of Titan."

Duncan Geere is a senior staff writer at He can be found on Twitter at @DuncanGeere. Follow Wired at @WiredUK


  1. Rumour has it ( Wikileaked even ) that the esoteric substance that appeared in this copy cat system looked rather like Cornflakes and we all know they are rubbish without milk; so what's with this waterless life and boring breakfast ... by the way ... the "energetic particles" are probably just sugar !  

    anthony connor- bingham
    Jan 8th 2011

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