Scientists say Jupiter's moon Europa's icy crust may be pure underwater snow that rises to the surface rather than falling down. Researchers believe this crust is formed in part by icing, a fluffy collection of ice crystals that similarly accumulate under Earth's ice sheets, Live Science reports..

Such an ice layer contains some of the salt found in the ice that grows on the ice shelf itself.. Scientists think this may indicate that Europa's ice crust may be less salty than previously thought..

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For astrobiologists, Europa is one of the most intriguing celestial bodies in the solar system.. According to NASA, Jupiter's moon covers an ocean 60-150 kilometers deep, covered with an ice crust 15 to 25 kilometers thick.. Europa is the size of a quarter of the Earth, but its ocean can hold twice as much water as all of Earth's oceans.. This makes this moon of Jupiter an interesting target for the search for extraterrestrial life..

NASA's new orbiter, Europa Clipper, scheduled to launch in October 2024, should fly past an icy moon and see if it could be habitable.. Scientists from the University of Texas at Austin are developing a radar device that should penetrate the ice layer of Europa..

As part of the radar effort, scientists sought to understand how Jupiter's moon's ice sheet might work.. Looking for clues, they turned to Earth, studying two main ways ice formed under the ice sheets of Antarctica.. One form, frozen ice, grows from the surface of an ice shelf.. The other, rocky ice, forms in cold seawater and drifts upward in flakes like reverse snow, eventually becoming trapped under the ice sheet..

Europe, like Antarctica, likely has a low temperature gradient. This means that the temperature changes little with depth..

In such conditions, rocky ice or icing is often encountered, especially in places where the ice thins into cracks or breaks..

If ice is also common on Europa, this could be of great importance for the formation of the satellite's ice crust.. While frozen ice may contain 10% of the salt of the surrounding sea water, ice is much cleaner, containing only 0.1% of the salt of the sea water from which it was formed..

This low-salt ice could affect the structure and strength of Europa's ice crust, as well as how well the Clipper radar can penetrate the ice..