BBC Knowledge Asia Edition

Enceladus, however, nature has gifted us a

way of analysing the ocean just by f lying

past the world. This is because there are

geysers jetting water from the ocean into

space.

NASA’s Cassini spacecraft has been

targeting those plumes and f lying

through them, so that its onboard

instruments can analyse them. Various

types of dust grains and chemical have

been discovered in this way, including

the telltale signature of salts.

“This is pretty good evidence that we

are sampling the ocean itself,” says

Enceladus is believed to have a low-density

rocky core and an icy outer shell, with an

ocean of liquid water sandwiched in-between

PHOTO: NASA X2

ENCELADUS

Parent planet: Saturn

Orbital period: 0.395 days

Radius: 0.0395 Earth radii

Mass: 0.000018 Earth mass

Planetary Habitability Index: 0.35

Although Europa was in many ways the trailblazing

moon for sub-surface oceans, much remains unknown

because the water is mostly locked under the ice. At

SCIENCE