How chemical reactions on a lifeless planet, floating around in the cold darkness of space, can suddenly give rise to living organisms is one of the biggest questions in science. We don’t even know whether the molecular building blocks of life on Earth were created here or whether they were brought here by comets and meteorites.
Using data from the NASA/ESA Cassini mission, we have now discovered molecules on Saturn’s largest moon, Titan, which we think drive the production of complex organic compounds. These are molecules that have never been seen in our solar system before. The discovery not only makes Titan a great contender for hosting some sort of primitive life, it also makes it the ideal place to study how life may have arisen from chemical reactions on our own planet.
The molecular building blocks of life are organic compounds that include amino acids, which can be assembled into proteins, RNA and DNA in living cells. To date, scientists have found these compounds in meteorites, comets and interstellar dust. The problem is, the materials formed millions of years ago, which means we have no way of knowing how they were created.
Excitingly, it seems those compounds are being created on Titan today. Sunlight and energetic particles from Saturn’s magnetosphere drive reactions in the moon’s upper atmosphere, which is dominated by nitrogen, methane and hydrogen. These lead to larger organic compounds which drift downward to form the moon’s characteristic “haze” and extensive dunes, eventually reaching the surface.
To make these surprising discoveries, which were published in the Astrophysical Journal Letters, the Cassini spacecraft dipped through Titan’s upper atmosphere. Using…