The shell of Jupiter’s famous icy moon may be made up, in part, of pure underwater snow that floats up instead of falling.
A new study, published in the August issue of the journal astrobiology, finds that Europa’s icy crust may be partially built of “brittle ice,” a spongy accumulation of ice crystals that also accumulates beneath ice sheets on Earth. This frazil ice contains a fraction of the salt found in ice growing from the ice shelf, suggesting that Europa’s ice sheets may be less salty than previously thought.
“When we’re exploring Europa, we’re interested in the salinity and composition of the ocean, because that’s one of the things that will govern its potential habitability or even the kind of life that could live there,” lead author of studio, Natalie Wolfenbarger. , a graduate student researcher at the University of Texas Geophysics Institute, said in a statement.
Related: What are the different types of ice formations found on Earth?
For astrobiologists, Europa is one of the most intriguing objects in the solar system. The moon is covered by an ocean 40 to 100 miles (60 to 150 kilometers) deep, covered by a crust of ice 10 to 15 miles (15 to 25 km) thick, according to NASA. Europa is a quarter the size of Earth, but its surface ocean may hold about twice as much water as all of Earth’s oceans, according to the space agency, making the moon an intriguing place to search extraterrestrial life
A new NASA orbiter, Europa Clipper, will launch in October 2024 to fly by the icy moon to see if it might be a suitable habitat for life. Scientists at the University of Texas at Austin are leading the development of Europa’s Clipper ice-penetrating radar instrument, which will look at the ice sheet and the ocean just below.
As part of this effort, the researchers wanted to understand how the ice sheet might be structured.
They turned to Earth as an analogue, examining the two main ways ice forms under the Antarctic ice sheets. One form, freezing ice, grows from the surface of the ice shelf.
The other, frazil ice, forms in cold seawater and drifts upward as flakes like inverse snow, eventually becoming trapped under the ice sheet.
Europa, like Antarctica, probably has a low temperature gradient, meaning that the temperature changes little with depth.
Under these conditions, Wolfenbarger found, frazil ice is quite common, especially in places where the ice thins into cracks or fractures. If frazil ice is also common in Europa, it could make a big difference in the composition of the Moon’s ice shell.
While freezing ice can contain 10 percent of the salt in the surrounding seawater, frazil ice is much purer, containing only 0.1 percent of the salt in the water of sea that forms
This low-salt ice could not only affect the structure and strength of Europa’s ice crust, but also affect the degree to which Clipper’s radar penetrates the ice.
“This paper is opening up a whole new set of possibilities for thinking about ocean worlds and how they work,” said 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 the Europa Clipper ice analysis.”
This article was originally published by Live Science. Read the original article here.
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