A moon of Saturn is known to have a variety of carbon-based molecules that apparently formed in its hidden ocean, an environment that scientists believe could be where life began, according to new research.
NASA’s Cassini spacecraft passed among the massive plumes that erupted from Enceladus in 2008. The plumes, which rose about 9,600 kilometers above the moon’s icy surface, contained water and salt, but also a complex mixture of carbon molecules.
These compounds, on Earth, usually arise from reactions between hot water and rock around hydrothermal vents on the sea floor, where many scientists believe to be the location of the origins of life on our planet.
Cassini has previously detected small ice grains in Saturn’s rings that contain organic molecules and precursors of amino acids, the basic building blocks of proteins.
Scientists have long believed that material from Saturn’s ‘E ring’ comes from Enceladus. However, these samples could be hundreds of years old and have undergone changes due to cosmic radiation. Therefore, samples are needed that are purer and taken closer to the source.
Nozair Khawaja, lead author of the latest study published in Nature Astronomy, said that this data has actually been around for a long time, but is not yet fully understood.
“With more knowledge, experience and experimentation, we reanalyzed the data from the flyby mission in more depth and understood the features we had detected for the first time,” Khawaja told Mashable.
The researchers said that the organic compounds found most likely came from the ocean floor of Enceladus, not from outer space contamination.
Cassini sampled the fresh grains using the Cosmic Dust Analyzer instrument, just minutes after Enceladus ejected them. This data was collected during Cassini’s flyby at more than 64,000 kilometers per hour, one of the fastest flybys of the mission.
This high speed actually increased the team’s confidence in their findings. The reason is, particles that collide at this speed break up in a special way, making it easier to detect organic molecules, explained Khawaja, who now works at the Freie Universität Berlin.
In laboratory experiments, the team of scientists simulated conditions in which ice grains hit detectors at both high and low speeds. The results were similar, meaning the chemical signals they saw were not caused by collisions, but were genuine characteristics of the molecules.
The new research also compared organic molecules previously discovered in Saturn’s E ring with fresh ice grains, and the results were consistent. This strengthens the suspicion that the ring material does come from the subsurface ocean of Enceladus.
The research team also discovered new organic compounds, indicating that the chemistry in Enceladus’ ocean is much more complex than once thought. They detected ring-shaped carbon molecules and oxygen-linked molecules, such as aldehydes, which on Earth can be precursors to amino acids.
Also found were esters, alkenes and ethers, types of compounds commonly found in living things in the form of fats and oils. In addition, the granules contain traces of nitrogen-oxygen compounds such as acetonitrile or pyridine.
So far, Cassini has discovered five of the six elements essential for Earth-like life on Enceladus. The only element that has not been discovered is sulfur.
The team is still conducting experiments in the laboratory using sulfur compounds to see whether the signals can match the simulations. It could be that sulfur is just an element that is more difficult to detect.
The results of this study further strengthen the European Space Agency’s (ESA) plans to carry out a follow-up mission that will orbit and land on Enceladus in the future.
“This finding further increases its habitability potential,” said Khawaja. “And further underscores the need for a new mission to Enceladus.”
