Study: Enceladus ice grains are sorted on the way out, not a direct ocean sample

A new Science Advances paper analysed about 1,000 mass spectra of salt-rich ice grains from Enceladus' plume collected by Cassini. The grains fall into at least five compositional subtypes by dominant salt, and salt separation only occurs in droplets larger than 10 micrometres freezing slower than 20 kelvins per minute before shattering against vent walls at over 100 metres per second.

• About 1,000 mass spectra of salt-rich plume grains were analysed
• Grains fall into at least five subtypes by dominant salt
• Salt separation needs droplets over 10 micrometres freezing slower than 20 K/min
• Grains accelerate past 100 m/s in vents and shatter on the walls