A research funded by NASA has obtained new images of Mercury, which suggest the planet is not only tectonically active like Earth but is also still shrinking.

In a paper published in Nature Geoscience, images from NASA's Mercury Surface, Space Environment, Geochemistry and Ranging (MESSENGER) spacecraft showed small fault scraps that were undetected previously. Scarps are landforms similar to cliffs in appearance and look a lot like stair steps.

The fault scarps discovered in Mercury are small enough to make scientists believe that they are geologically young, which also means that tectonic activity is still active in the planet and that it is still shrinking.

Previously, scientists thought that the Earth was the only planet in the solar system with active tectonic activity.

"For years, scientists believed that Mercury's tectonic activity was in the distant past. It's exciting to consider that this small planet ... is active even today," said Jim Green, NASA Planetary Science director.

According to Thomas Watters, lead author of the paper and Smithsonian senior scientist at Washington, D.C.'s National Air and Space Museum, the fault scarps likely formed as Mercury's interior continued to cool and it contracted.

Mercury's larger fault scarps were first identified in the mid-1970s from flybys from the Mariner 10. These scarps were then confirmed by MESSENGER, which discovered that the planet was shrinking. Like the newly spotted smaller scarps, the larger ones were formed as the planet's interior cooled and contracted, resulting in breaks in its surface as the crust was thrust upward. The larger fault scarps are hundreds of miles long, with some more than a mile high.

MESSENGER was able to get a closer look at Mercury in the last 18 months of its mission because the spacecraft was flying at a lower altitude, allowing higher-resolution images of the planet. It was in these images that the small fault scarps were found.

Young enough to survive the relentless bombardment from comets and meteoroids, the small fault scarps on Mercury were found to be comparable in scale to those found on Earth's moon, which also indicated that it was also shrinking.

According to scientists, the active tectonic activity on Mercury is in line with recent findings showing that the planet's global magnetic field has been in place for billions of years, existing as Mercury's still-hot outer core slowly cooled.

This also makes it possible for Mercury to experience quakes, although this kind of activity on the planet is yet to be confirmed. For now, scientists have determined that Mercury is tectonically active.

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