The National Aeronautics and Space Administration (NASA) has been a blur of activity over the past few days. With the press brief about Jupiter's Europa and the findings about the dwarf planet Pluto, a NASA-funded research tops it all off with results showing that our Earth is no longer the only planet showing tectonic activity.
In a study published in Nature Geoscience, the final high resolution images that NASA robotic spacecraft MESSENGER (Mercury Surface, Space Environment, Geochemistry, and Ranging) took before smashing into Mercury shows that it is geologically active. The images revealed several things pointing to this conclusion: young fault scraps, surface offset and the shrinking of Mercury's crust.
Previous research found the fault scraps, or cliff-like landforms, during the flybys of Mariner 10 and confirmed by MESSENGER, and was assumed to have happened centuries ago when Mercury's interior was thought to be cooling and concluded that the activity has to be over. But in the final year and a half of MESSENGER's mission, it found younger fault scraps which indicated that Mercury is still shrinking.
"This is why we explore," said Planetary Science Director Jim Green, as reported by NASA. "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."
Though the large fault scraps are easy to see, the truly baffling aspect of the study was the younger ones that should not have survived through the constant meteor impacts experienced by Mercury, especially if it appeared millions or billions of years ago.
According to Gizmodo, the study's lead author Thomas Watters said that if technology allows mankind to put a seismometer on Mercury as they have on the moon, there's a "very good chance it could detect Mercury quakes associated with continued contraction." The activity of Mercury looks like it might just suffer the same fate of Pluto when the title of planethood was taken away from it. Fortunately, there's a limit to how much Mercury can shrink and to date, it still qualifies as a planet.
"MESSENGER has opened up a new door into this question of how Mercury has evolved," said Watters. "We're starting to see this picture that, in my mind, is going to change the way we think about terrestrial planets."
