The stunning surface of Europa as seen from this reprocessed image taken by the Galileo spacecraft. Source: NASA

Weird Underwater Snow That Floats Upwards Helps Build Europa’s Thick Icy Crust

The bizarre underwater snow is known to form beneath Earth's ice shelves, but a new study suggests that it may also form on Jupiter's moon, where it may assist with its Europas massive icy rust.


Inverted ice peaks and submerged ravines adorn Europa’s thick icy crust; at its bottom lies a vast, global ocean, where snow floats upwards.

The bizarre underwater snow is known to form beneath Earth’s ice shelves, but a new study suggests that it may also form on Jupiter’s moon, where it may assist with its Europas massive icy rust.


Due to the extreme purity of underwater snow, Europa’s ice shell might be significantly less salty than previously believed. 

The Europa Clipper mission will use radar to determine whether Europa’s ocean is habitable for life as we know it. This information is critical for mission scientists preparing the spacecraft. 

To make sense of the data, scientists will need to know what the ice is made of since salt trapped in the ice can affect what and how deep the radar can see.

What’s up, Europa?

The University of Texas at Austin led the study, which appeared in Astrobiology in August. Also, this university is developing Europa Clipper’s ice-penetrating radar instrument. Europa’s shell is made of ice, so knowing what kind it is will also be helpful in discovering its ocean’s salinity and habitability.

“The salinity and composition of Europa’s ocean are important factors when we explore it, as they determine its potential habitability or even what type of life might exist there,” said the study’s lead author, Natalie Wolfenbarger, a graduate student at the University of Texas Institute for Geophysics (UTIG) in the UT Jackson School of Geosciences.

Europa, which is a rocky world approximately the size of Earth’s Moon, is home to a vast global ocean wrapped in a miles-thick outer shell made of ice.


Europa is Jupiter’s fourth largest satellite and the sixth largest moon in the solar system. Even though its surface appears cracked and discolored, it is one of the smoothest solid objects in the solar system. Most of its peaks are only a few hundred meters high, and there are few large craters. Striking patterns across its icy surface are probably mostly due to shallow fractures and the different composition of the ground, not to enormous canyons like on other planets.

According to previous studies, the ocean near Europa’s ice shelf has a similar temperature, pressure, and salinity to Antarctica’s ocean.

Curious Ice

Accordingly, the study investigated congelation ice and frazil ice, two different ways water freezes under ice shelves. 

Ice that has frozen directly under the ice shelf is called congelation ice. Frazil ice is different. A shelf of ice forms when ice flakes float upward through supercooled seawater and settle to the bottom.

In both cases, Wolfenbarger found ice made in these ways is less salty than seawater, and that’s true even when scaled up to the size and ages of Europa’s ice shell. Additionally, frazil ice – which contains only a small fraction of the salt in seawater – could be relatively common on Europa. 

It would mean its ice shell is many orders of magnitude purer than previous estimates suggested. As a result, everything from its strength to how heat travels through it is affected, as well as the forces which may drive ice tectonics.

“This paper is opening up a whole new batch of possibilities for thinking about ocean worlds and how they work,” revealed Steve Vance, a research scientist at NASA’s Jet Propulsion Laboratory (JPL) who was not involved in the study. “It sets the stage for how we might prepare for Europa Clipper’s analysis of the ice.”

Donald Blankenship, co-author and principal investigator for Europa Clipper’s ice-penetrating radar instrument, says the research validates the use of the Earth as a model to study Europa’s habitability.

The Earth can be used for evaluating Europa’s habitability, measuring the exchange of impurities between ice and ocean, and determining where the water is located inside the ice.


Europa Clipper

Jupiter’s moon Europa will be surveyed by NASA’s Europa Clipper, which will determine if it is suitable for life.

The spacecraft will investigate Europa, a world showing evidence of a liquid ocean beneath its icy crust that may host life. In this mission, a highly capable and radiation-tolerant spacecraft will orbit Jupiter for a long time, during which it will fly as close as possible to the icy moon.

The Europa Clipper mission is expected to launch in October 2024.

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Written by Ivan Petricevic

I've been writing passionately about ancient civilizations, history, alien life, and various other subjects for more than eight years. You may have seen me appear on Discovery Channel's What On Earth series, History Channel's Ancient Aliens, and Gaia's Ancient Civilizations among others.

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