Nav: Home

Close encounters of a tidal kind could lead to cracks on icy moons

May 25, 2016

A new model developed by University of Rochester researchers could offer a new explanation as to how cracks on icy moons, such as Pluto's Charon, formed.

Until now, it was thought that the cracks were the result of geodynamical processes, such as plate tectonics, but the models run by Alice Quillen and her collaborators suggest that a close encounter with another body might have been the cause.

Astronomers have long known that the craters visible on moons were caused by the impact of other bodies, billions of years ago. But for every crash and graze, there would have been many more close encounters. By devising and running a new computer model, Quillen, a professor of physics and astronomy at Rochester, has now shown that the tidal pull exerted by another, similar object could be strong enough to crack the surface of such icy moons. Quillen also thinks that "it might even offer a possible explanation for the crack on Mars, but that's much harder to model."

Icy moons exhibit what is know as brittle elastic behavior, which Quillen says most resembles "silly putty."

"If you take silly putty and throw it on the floor it bounces - that's the elastic part," said Quillen. "But if you pull on it rapidly and hard enough, it breaks apart."

To simulate the behavior, Quillen modeled the icy moons as if their interior was made up of many bodies connected by springs (an N-body problem with springs). While N-body problems are often used to understand the effect of gravity on planets and stars, N-body problems had never been used to model the inside of an astronomical body, in this case the moons. Other models for icy moons used what are known as "rubble pile models."

"I was inspired by computer graphics code in how to model the icy moons," said Quillen. "The inside of the moons is similar to how blood splatter is modeled in games and the outer, icy crust is similar to modeling clothes and how they move. But I had to ensure the code matched the underlying physics!"

To ensure her model took into account the right properties for the materials that make up the moons, she worked with earth sciences Professor Cynthia Ebinger.

"I jumped at the opportunity to consider a novel alternative to plate tectonics, the governing theory to explain earthquakes, volcanoes and moving plates on Earth," said Ebinger. "My role was to provide some checks and balances to Alice's modeling and the choice of model parameters."

In the paper, to be published by the journal Icarus, Quillen states that "strong tidal encounters" may be responsible for the cracks on icy moons such as Charon, Saturn's Dione and Tethys, and Uranus' Ariel.

The key factor in determining if a crack is going to occur is the strain rate, the rate of pull from another body that would have caused the moons to deform at a rate that the top, icy layer could not sustain - leading to cracks.

In a companion paper, published in Monthly Notices of the Royal Astronomical Society, Quillen has shown that her models are consistent with the rate at which moons spin up or down when orbiting another object.
Quillen's and Ebinger's co-authors on the paper are David Giannella and John G. Shaw, also at the University of Rochester.

The work was in part supported by NASA grant NNX13AI27G.

University of Rochester

Related Plate Tectonics Articles:

The birth and death of a tectonic plate
Geophysicist Zachary Eilon developed a new technique to investigate the underwater volcanoes that produce Earth's tectonic plates
Experts explain origins of topographic relief on Earth, Mars and Titan
The surfaces of Earth, Mars, and Titan, Saturn's largest moon, have all been scoured by rivers.
Scientists describe origins of topographic relief on Titan
Fluid erosion has carved river networks in at least three bodies in our solar system in the form of water on Earth and Mars and liquid hydrocarbons on Titan.
Southern Italy: Earthquake hazard due to active plate boundary
Tectonically, the Mediterranean is extremely active and thus threatened by natural catastrophes.
Release of water shakes Pacific Plate at depth
A team of seismologists analyzing the data from 671 earthquakes that occurred between 30 and 280 miles beneath the Earth's surface in the Pacific Plate as it descended into the Tonga Trench were surprised to find a zone of intense earthquake activity in the downgoing slab.
SLU geologists discover how a tectonic plate sank
Saint Louis University researchers report new information about conditions that can cause the Earth's tectonic plates to sink into the Earth.
The evolution of antibiotic resistance, on a plate
Researchers have developed a large culturing device to track the evolution of bacteria as they mutate in the presence of antibiotics, revealing that, surprisingly, the fittest mutants were not those most likely to infiltrate higher antibiotic concentrations.
Crystallization plate provides clues on protein structure aboard historic space mission
A new crystallization plate, developed and tested at the Cornell High Energy Synchrotron Source, or CHESS, hitched a ride to outer space and is helping a major drugmaker learn about protein structure.
New insights on the relationship between erosion and tectonics in the Himalayas
Can processes unfolding at the Earth's surface be strong enough to influence tectonics?
Earth's mantle appears to have a driving role in plate tectonics
Deep down below us is a tug of war moving at less than the speed of growing fingernails.

Related Plate Tectonics Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Jumpstarting Creativity
Our greatest breakthroughs and triumphs have one thing in common: creativity. But how do you ignite it? And how do you rekindle it? This hour, TED speakers explore ideas on jumpstarting creativity. Guests include economist Tim Harford, producer Helen Marriage, artificial intelligence researcher Steve Engels, and behavioral scientist Marily Oppezzo.
Now Playing: Science for the People

#524 The Human Network
What does a network of humans look like and how does it work? How does information spread? How do decisions and opinions spread? What gets distorted as it moves through the network and why? This week we dig into the ins and outs of human networks with Matthew Jackson, Professor of Economics at Stanford University and author of the book "The Human Network: How Your Social Position Determines Your Power, Beliefs, and Behaviours".