Is methanol on Enceladus a sign of extraterrestrial life?

The emissions of Enceladus geysers contain a lot of methanol, the simplest organic alcohol, whose presence in the waters of the moon of Saturn, however, is not proof of the existence of life in its ocean, the planetologists said at the annual meeting of the Royal Astronomical Society of Great Britain.

“The discovery of the oceans on the moons of the giant planets and the potential conditions for the birth of life in them made us wonder if it exists there, but unfortunately, in this case methanol does not arise in the bowels of Enceladus, but at the moment when the water is thrown by the geysers in Space. “Therefore, the molecules of this alcohol can hardly be considered a trace of life,” said Emily Drabek-Maunder of the University of Cardiff, UK.

In 2005, Cassini discovered on Enceladus jets of particles of water ice and steam, which are ejected into outer space from parallel cracks near the south pole – the so-called “tiger stripes”. This discovery raised the question of the source of this pair and ice for scientists.

In March 2015, 10 years after the discovery of tiger stripes and geysers on Enceladus, the Cassini probe showed that in the bowels of this satellite of Saturn, there is a global ocean of liquid and hot water, discovering sand particles and frozen water droplets ejected from the South Pole Enceladus with eruptions of geysers. A year ago, planetologists found a potential source of energy for life on Enceladus – a large amount of hydrogen in its emissions.

According to Drabek-Maunder, planetologists have long known about the presence of one of the potential traces of life in the waters of Enceladus, alcohol-methanol molecules, which were discovered in its emissions by the Cassini probe a few years ago. Methanol, scientists explain, can appear in water and in outer space during “lifeless” chemical reactions, and therefore planetologists have long tried to understand where it came from in the waters of Saturn’s moon.

Drabek-Maunder and her team discovered the source of methanol quite by accident, observing with the help of a number of terrestrial radio telescopes behind the E ring of Saturn, the ice reserves in which are constantly replenished by the emissions of Enceladus geysers. As the scientists note, they initially just watched the movement of ice and dust in this ring and did not expect to find methanol here.

Contrary to their expectations, Ring E contained an unusually large amount of this alcohol, at times more than the geyser emissions themselves contain. This pointed to two things – that methanol is formed not in the depths of Enceladus, but in space, and that it has not a biological but abiogenic origin. Falling into the ring E, molecules of methanol and gases, thrown into space along with the water of the geysers, are held there by the magnetic field of Saturn and accumulate in sufficient quantities to be seen by a relatively modest radio telescope from the Earth.

The discovery of methanol in the emissions of Enceladus from Earth observations, as Drabek-Maunder notes, indicates that traces of life on its surface and in its vicinity can also be sought with the help of the largest terrestrial observatories such as Arecibo or the recently launched 500-meter FAST radio telescope. On the other hand, the interpretation of their data will require the launch of another probe to Saturn, as the Cassini will complete its mission and burn in the atmosphere of the “Lord of the Rings” in mid-September.