New high resolution images reveal Mercury is tectonically active

By AG Staff/NASA September 27, 2016
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Mercury joins Earth as the only known tectonically active planet in our Solar System.

NEW IMAGES FROM NASA’s MESSENGER spacecraft have revealed previously undetected fault scarps – cliff-like landforms – on Mercury that are small enough to suggest the planet is geologically young.

Published in Nature Geoscience, the new NASA findings suggests that Mercury is still contracting, and that Earth is not the only tectonically active planet in our Solar System, as previously thought.

“The young age of the small scarps means that Mercury joins Earth as a tectonically active planet, with new faults likely forming today as Mercury’s interior continues to cool and the planet contracts,” said lead author Tom Watters, Smithsonian senior scientist at the National Air and Space Museum in Washington, D.C.

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Mercury is the closest planet to the Sun in our Solar System. It is also now known to be the only other planet in our Solar System to be tectonically active. (Source: NASA/JHUAPL/Carnegie Institution of Washington/USGS/Arizona State University)

Large fault scarps were first discovered on Mercury in the mid-1970s. The large scarps were formed as Mercury’s interior cooled, causing the planet to contract and the crust to break and thrust upward along faults, making cliffs up to hundreds of kilometres long and some more than 1.5km high.

In the last 18 months, the altitude of NASA’s MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft was lowered, allowing the surface of Mercury to be seen at much higher resolution. These images revealed much smaller fault scarps that researchers say have to be very young to survive the steady bombardment of meteoroids and comets.

“For years, scientists believed that Mercury’s tectonic activity was in the distant past. It’s exciting to consider that this small planet – not much larger than Earth’s moon – is active even today,” said NASA Planetary Science Director Jim Green.