Enceladus is a small moon of Saturn. Under its icy surface, there is probably a salty ocean. The moon sends water into space as tiny pieces of ice. A spacecraft called Cassini studied about 1,000 of these salty ice grains.

Scientists found that each grain mostly had one kind of salt, such as table salt or baking soda. The salts were sorted, like things in different boxes.

Saturn's small moon Enceladus has a salty ocean under its ice, and it sprays ocean water into space as tiny ice grains. An international team, including researchers from the Free University of Berlin and Japanese universities, analyzed data on 961 salt-rich grains collected by the Cassini spacecraft.

Earlier studies had averaged the contents of many grains, but this team looked at each grain separately. They found at least five types of grains, each rich in a particular salt, such as sodium chloride or sodium carbonate. Laboratory experiments suggested that slow freezing of ocean spray, followed by collisions inside narrow ice cracks, can sort the salts. The study was published in Science Advances.

Beneath the icy crust of Enceladus, a 500-kilometer-wide moon of Saturn, lies a salty ocean that vents material into space through cracks near its south pole. A Science Advances study by an international team, including researchers at the Free University of Berlin as well as scientists from the Institute of Science Tokyo and Kanazawa University, examined Cassini dust-analyzer data on 961 salt-rich ice grains collected in Saturn's E ring.

Instead of averaging the grains, the team analyzed them individually and identified at least five compositional types, each dominated by a particular salt, such as sodium chloride, sodium carbonate, or sodium phosphates. Laboratory experiments and thermodynamic calculations suggest a two-step mechanism: large droplets of ocean spray freeze slowly, allowing different salts to crystallize separately, and the frozen particles are then accelerated through narrow vents and broken apart by repeated collisions. This natural sorting could help future missions, because analyzing grains one by one may reveal faint substances that would be diluted if many grains were melted together. However, Cassini ended its mission in 2017, so the conclusions rely on archived data and experiments, and they do not indicate that life exists there.