Underwater snow reveals new clues to Europa as ocean missions draw closer | CNN

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Jupiter’s icy moon Europa is an ocean world locked under a thick crust of ice – a place where snow floats up.

Underwater snow forms in the global ocean and rises through the water to attach to submerged ravines and inverted ice peaks, new research shows. This same phenomenon occurs under the ice shelves on Earth – and this may be how Europa builds its ice shell.

The finding, published Monday in the journal Astrobiology, suggests that Europa’s ice shell may not be as salty as scientists first thought. Understanding the salt content of the ice crust is crucial as engineers work to assemble NASA’s Europa Clipper spacecraft, which prepares to launch to Europa in October 2024.

Europa Clipper will use ice-penetrating radar to look beneath the shell and determine if the moon’s ocean is potentially habitable for life. Any salt in the ice shell could impact how deep radar can penetrate through it, so predictions about shell composition are critical.

READ MORE: Find out where the search for life is taking place in our solar system

Clues to the ice shell could also help scientists learn more about Europa’s ocean, its salinity and its potential to harbor life.

Europa’s ice shell is between 10 and 15.5 miles (15 and 25 kilometers) thick and likely lies over an ocean that is estimated to be 40 to 90 miles (60 to 150 kilometers) deep ).

“When we explore Europa, we are interested in the salinity and the composition of the ocean, because that is one of the things that will govern its potential habitability or even the type of life that could live there,” said l lead author of the study, Natalie. Wolfenbarger, a doctoral student at the University of Texas Institute of Geophysics at UT Jackson School of Geosciences, in a statement.

Wolfenbarger is also a graduate student member of the Europa Clipper science team. Researchers at the University of Texas at Austin are developing the spacecraft’s ice-penetrating radar.

The ocean in Europa closest to its shell has a similar temperature, pressure and salinity to the water under Antarctica’s ice shelves, previous research has suggested.

Researchers studied the two methods of freezing water under ice shelves on Earth: freezing ice and frazil ice.

What is the difference? Freezing ice actually pushes under the ice shelf, while frazil ice drifts upward through supercooled seawater in flakes before settling under the ice shelf.

Both of these types result in ice that is less salty than seawater – and according to the researchers’ projections, the seawater was even less salty when they applied this data to the age and scale of Europe’s ice shell.

Frazil ice is perhaps the most common type on Europa, which would make the ice shell much purer than previously thought. Frazil ice preserves only a tiny fraction of the salt that exists in seawater. The purity of the ice shell can impact its strength, the tectonics of the ice, and the way heat flows through it. the shell.

“We can use Earth to assess the habitability of Europa, measure the exchange of impurities between the ice and the ocean, and determine where the water is in the ice,” said the co-author of the paper. study, Donald Blankenship, principal investigator at the University of Texas Institute of Geophysics. , in a report. He is the principal investigator of Europa Clipper’s ice-penetrating radar instrument.

The finding may suggest that Earth can be used as a model to better understand Europa’s habitability.

Previous missions have seen plumes of water vapor gushing through the ice shell, as shown in this illustration.

“This paper opens up a whole new set of possibilities for thinking about ocean worlds and how they work,” Steve Vance, a researcher at NASA’s Jet Propulsion Laboratory in Pasadena, California, said in a statement. “This paves the way for how we might prepare for analysis of the Europa Clipper ice.” Vance did not participate in the study.

Meanwhile, work is underway on the core of the Europa Clipper spacecraft at the Spacecraft Assembly Facility at NASA’s Jet Propulsion Laboratory.

The core, which is 10 feet (3 meters) high and 5 feet (1.5 meters) wide, took center stage in the Clean Room, where NASA teams assembled spacecraft like Galileo , Cassini and the Mars rovers.

The mission team is currently assembling Europa Clipper at High Bay 1, a clean room at NASA's Jet Propulsion Laboratory where other historic missions were staged prior to launch.

Flight hardware and scientific instruments will be installed on the spacecraft by the end of the year. Next, engineers will put the spacecraft through a series of tests as it prepares for launch.

Europa Clipper will arrive on the Jovian moon in April 2030. Out of nearly 50 planned flybys of Europa, the spacecraft will eventually drop from an altitude of 1,700 miles (2,735 kilometers) to just 16 miles (25 kilometers) above from the surface of the moon.

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