Moonquakes could 'smooth out' the surfaces of Jupiter and Saturn's icy moons - Space.com

Moonquakes may be be smoothing out the surfaces of moons orbiting gas giant planets Jupiter and Saturn, new research has revealed. The findings could solve a long-standing mystery regarding why many of these icy moons have such smooth terrain.

Scientists have known for some time that some of the moons that orbit the gas giants Jupiter and Saturn, the largest and second-largest planet in the solar system respectively, are geologically active. This is the result of the massive gravitational influence of these planets that stretches and squeezes the moons orbiting them, triggering moonquakes that crack the moon's crusts and icy surfaces.

This new research implies these moonquakes can also trigger landslides that help create smooth terrains. The link between moonquakes and landslides indicates how the surfaces of these moons evolve.

Steep ridges surrounded by relatively smooth areas are a common sight across the landscapes of the Jovian moons Europa and Ganymede, as well as Saturn's moon Enceladus. While scientists have speculated that these features are the work of liquid flowing from icy volcanoes, quite how the process works at low temperatures on these frigid moons that are inhospitable to liquids, has been a puzzle.

The explanation put forward in this new research doesn't require the presence of liquid on the surface of these icy moons, however.

The team came to the surprising conclusion when they set about measuring the dimensions of these ridges, thought to be steep slopes caused by the surface breaking along a fault line with one side dropping in what scientists call "tectonic fault scarps." They then applied the measurements to seismic models which allowed them to estimate the power of moonquakes in the history of these moons.

This revealed that some of these seismic events would have been strong enough to hoist up debris that then rolls downhill, spreading out as it does so and smoothing out the landscape of the moons.

"We found the surface shaking from moonquakes would be enough to cause surface material to rush downhill in landslides. We've estimated the size of moonquakes and how big the landslides could be," research lead author and University of Arizona in Tucson graduate student Mackenzie Mills, said in a statement (opens in new tab). "This helps us understand how landslides might be shaping moon surfaces over time."

The research conducted by Mills during a series of summer internships at NASA's Jet Propulsion Laboratory in Southern California will get a major boost when NASA's Europa Clipper mission heads to Europa in 2024.