NASA | MESSENGER | 2016 Sep 26
It’s small, it’s hot, and it’s shrinking. New NASA-funded research suggests that Mercury is contracting even today, joining Earth as a tectonically active planet.
[c][attachment=0]mercury_4.jpg[/attachment][/c]Images obtained by NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft reveal previously undetected small fault scarps— cliff-like landforms that resemble stair steps. These scarps are small enough that scientists believe they must be geologically young, which means Mercury is still contracting and that Earth is not the only tectonically active planet in our solar system, as previously thought. ...
Large fault scarps on Mercury were first discovered in the flybys of Mariner 10 in the mid-1970s and confirmed by MESSENGER, which found the planet closest to the sun was shrinking. 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 miles long and some more than a mile (over one-and-a-half kilometers) high.
In the last 18 months of the MESSENGER mission, the spacecraft’s altitude was lowered, which allowed the surface of Mercury to be seen at much higher resolution. These low-altitude images revealed small fault scarps that are orders of magnitude smaller than the larger scarps. The small scarps had to be very young, investigators say, to survive the steady bombardment of meteoroids and comets. They are comparable in scale to small, young lunar scarps that are evidence Earth’s moon is also shrinking. ...
Mercury Found To Be Tectonically Active
Planetary Science Institute | 2016 Sep 26
Recent tectonic activity on Mercury revealed by small thrust fault scarps - Thomas R. Watters et al
- Nature Geoscience (online 26 Sep 2016) DOI: 10.1038/ngeo2814