Underwater snow reveals clues about Europa’s ocean world

Underwater snow reveals clues about Europa's ocean world
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Underwater snow forms in the global ocean and moves across the water to attach itself to underwater canyons and inverted ice caps, according to new research. This same phenomenon occurs beneath Earth’s ice shelves — which may be how Europa built its ice sheet.

The finding was published in the journal Monday Astrobiology, suggested that Europa’s ice sheet may not be as salty as scientists first thought. Understanding the salt composition of the ice crust is critical as engineers work to assemble NASA’s Europa Clipper spacecraft, which is set to launch to Europa in October 2024.

Europa Clipper will use ice-penetrating radar to look beneath the crust and determine whether the lunar ocean is potentially habitable for life. Any discontinuity within the ice sheet can affect how deep the radar can penetrate through it, so predictions of projectile composition are important.

Clues from the ice sheet could help scientists learn more about Europa’s ocean, its salinity and potential for life.

Europa’s ice sheet is between 10 and 15.5 miles (15 and 25 kilometers) thick and sits atop an ocean estimated to be between 40 and 90 miles (60 and 150 kilometers) deep.

“When we study Europa, we’re interested in the salinity and composition of the ocean because that’s one of the things that governs its potential habitability and even the type of life that could live there,” said Natalie, lead author of the study. Wolfenbarger, a postdoctoral researcher at the University of Texas Geophysics Institute at UT Jackson School of Geosciences, said 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 closest to Europa’s crust has the same temperature, pressure, and salinity as the water beneath the ice shelves in Antarctica. previous studies have suggested.

Researchers have studied two ways in which water freezes beneath Earth’s ice shelves: frozen ice and fractured ice.

Jupiter's moon Europa may have a habitable ice shell

What is the difference? Frozen ice actually grows from beneath the ice shelf, while frozen ice slides off the supercooled seawater as flakes before settling beneath the ice shelf.

Both of these types result in ice that is less salty than seawater, and the researchers predicted that seawater was less salty when they applied this data to the age and extent of Europa’s ice sheet.

Frazil ice may be the most common type in Europe, which would make the ice sheet much cleaner than previously believed. Frazil ice holds only a small fraction of the salt found in seawater. The purity of the ice crust can affect its strength, ice tectonics, and how heat flows through the crust.

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

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

Previous missions have observed plumes of water vapor erupting from the ice crust, as shown in this illustration.

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

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

The core, 10 feet (3 meters) tall and 5 feet (1.5 meters) wide, took center stage in the clean room where NASA teams assemble spacecraft such as the Galileo, Cassini and Mars rovers.

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

Flight instruments and scientific instruments will be installed on the spacecraft by the end of the year. Engineers will then run the spacecraft through a series of tests during launch.

Europa Clipper will reach the Jovian moon in April 2030. Over Europa’s planned 50 or so flybys, the spacecraft will eventually drop from an altitude of 1,700 miles (2,735 kilometers) to just 16 miles (25 kilometers) above the moon’s surface.

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