Alex McColgan

and was vaporised by the planet's atmosphere, in a self-destructive manoeuvre designed to protect potential habitable life on Enceladus and Titan from contamination by Earth-born microbes.

Though Cassini's mission had been completed, ours had not.

An analysis in 2018 had confirmed the existence of ring-shaped organic molecules and simple oxygen-containing molecules, indicating some limited chemistry was occurring.

Another huge boost to the search for life came in 2022, when the last element crucial to life was observed in the data – phosphorus.

With its discovery, we now had all six main elements believed to be necessary for life – carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulphur, which scientists know by the acronym CHINOPS.

For a while, this felt like the end of the story, but it turns out this particular book had a few more chapters to go.

When scientists first saw the mass spec data from Cassini, they weren't confident in what they were looking at.

It turns out that the spectra of a carefully prepared sample, analysed while stationary in a lab, looks somewhat different to the one obtained by crashing the detector into an ejector at 64,000 km per hour in space.

A mass spectrum analyser works by ionising and breaking a molecule apart at high energy.

how the molecule breaks apart matters.

A molecule's fingerprint can look different depending on how it was fragmented, in the same way that a watermelon prepared with a knife looks different from one prepared with a blender.

By understanding the typical pattern of how an object breaks under certain conditions, we can be more confident of what it used to be.

Improved analytical tools helped a team led by Nozea Kavajar from the Institute of Space Systems in Stuttgart do exactly that.

After more than a decade of studying the plume flybys, Kavajar's team published their results last year, using samples that were collected when Cassini passed just 20km from the Moon's surface.

In the most extreme examples, they found molecules more closely related to life than ever before – carbon dioxide, carbon-rich alkanes and alkenes.

cyclic esters and ethers, ethyls, and other nitrogen and oxygen-bearing compounds.

In other words, complex chemistry, potentially powered by hydrothermal vents.

These molecules are the Lego blocks of chemistry.

More functional groups allow for more complex reactions.

In a lab, these can become so complex that they even demonstrate Darwinian evolution.