Underwater snow reveals clues about Europe’s ocean world

Underwater snow reveals clues about Europe's ocean world
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Europa, Jupiter’s icy moon, is an ocean world encased in thick ice, a place where snow floats up.

Underwater snow forms in the global ocean and travels through water to adhere to submerged gullies and inverted ice spikes, according to new research. This same phenomenon takes place under ice shelves on Earth, and may be Europa’s way of building its ice sheet.

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

This illustration shows Europa Clipper making a flyby of the icy moon, with Jupiter in the background.

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

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

Clues about the ice sheet could also help scientists determine more about Europa’s ocean, its salinity, and its potential to support life.

Europa’s ice sheet is 10 to 15.5 miles (15 to 25 kilometers) thick, likely sitting on top of an ocean 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 determine its potential habitability or even the type of life that could live there,” said study lead author Natalie. Wolfenbarger, a doctoral student researcher at the University of Texas Institute for Geophysics at the UT Jackson School of Geosciences, in a statement.

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

Europa’s ocean closest to its shell has a temperature, pressure and salinity similar to that of the water beneath the ice shelves in Antarctica. Previous research has suggested.

The researchers studied the two methods of freezing water beneath ice shelves on Earth: freeze ice and brittle ice.

What is the difference? Freezing ice actually grows below the ice shelf, while brittle ice rises through supercooled seawater in flakes before settling below the ice shelf.

Both types result in ice that has less salinity than seawater, and the researchers projected that seawater was even less salty when they applied these data to the age and scale of Europa’s ice sheet.

Frazil ice may be the most common type on Europa, which would make the ice sheet much purer than previously believed. Frazil ice only retains a small fraction of the salt that exists in seawater. The purity of the ice sheet can affect its strength, ice tectonics, and how heat flows through the sheet.

“We can use Earth to assess Europa’s habitability, measure the exchange of impurities between the ice and the ocean, and find out where the water is in the ice,” said study co-author Donald Blankenship, a senior research scientist at the Institute of Geophysics from the University of Texas. , in a sentence. He is the principal investigator for the Europa Clipper 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 observed plumes of water vapor bubbling up through the ice sheet, as shown in this illustration.

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

Meanwhile, work is being done on the core of the Europa Clipper spacecraft at the spacecraft assembly facility at NASA’s Jet Propulsion Laboratory.

The core, which measures 10 feet (3 meters) tall and 5 feet (1.5 meters) wide, has taken center stage in the clean room, where NASA teams have assembled spacecraft such as Galileo, Cassini and Mars rovers.

The mission team is currently assembling Europa Clipper in High Bay 1, a clean room at NASA's Jet Propulsion Laboratory where other historic missions have taken place before launch.

Flight hardware and science instruments will be installed on the spacecraft by the end of the year. Engineers will then put the spacecraft through a series of tests during the lead-up to launch.

Europa Clipper will reach the Jovian moon in April 2030. Through nearly 50 planned flybys of Europa, the spacecraft will eventually go from an altitude of 1,700 miles (2,735 kilometers) to just 16 miles (25 kilometers) above the surface of the Earth. Moon.

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