14 DAY TRIAL // Despite missing liquid water, the atmosphere surrounding Saturn's largest moon, Titan, seems to be perfectly capable of producing DNA molecules, or at least some of the chemical precursors leading to these molecules. Scientists say that the “chain of life” may have already appeared high above the moon.
Investigations conducted over the years using the NASA Cassini spacecraft have revealed a large portion of the chemicals making up Titan's hazy, yellowish atmosphere. The main differences between it and its Earthly counterpart are the elements on which they are based.
While our plant relies on water to drive its atmosphere, climate, ocean temperatures, precipitations and so on, the Saturnine moon relies on liquid hydrocarbons for the same exact phenomena. The sole reason for that is the average temperature on the moon.
According to experts, average yearly temperatures on Titan reach values of around 93.7 degrees Kelvin, the equivalent of minus 179.5 degrees Celsius. In such extreme cold, frozen water arranges itself into a special type of ice, which is harder and tougher than granite.
However, these temperature ranges are precisely the ones between which hydrocarbons such as methane and ethane turn liquid. As such, Titan began using these chemicals for conducting its atmospheric cycles.
What this means is that all precipitations taking place on Titan involve liquid drops of methane and ethane falling onto lakes made by the exact same chemicals. But, while the surface is somewhat compromised for life, the atmosphere is not.
The Cassini orbiter has identified numerous chemicals floating hundreds of kilometers above the surface that cannot be found below the thick clouds. Of all the ingredients needed to make DNA, only liquid water is missing, Daily Galaxy reports.
“To the best of our knowledge, the original chemicals chosen by known life on Earth do not constitute a unique set; other choices could have been made, and maybe were made if life started elsewhere many times,” expert Paul Davies said recently.
What he implied by that is that DNA may have taken on a different shape on other worlds, based on the organic chemicals available there. It stands to reason that Titan's atmosphere may contain DNA which is not based on water, but on hydrocarbons.
“We're really starting to get a sense for what kind of chemistry an atmosphere is capable of” carrying out, University of Arizona planetary sciences graduate student Sarah Hörst says. She was the leader of the research effort that also involved Davies.
Davies is the director of BEYOND: Center for Fundamental Concepts in Science, and also the codirector of the Cosmology Initiative at the Arizona State University.