Mercury, the smallest and innermost planet in our solar system, has a surface composition that is different from what scientists previously believed. New research shows that Mercury's surface contains less silicon dioxide — a common component in rocks — than earlier estimates suggested. This discovery implies that Mercury's interior may have been hotter and more volcanically active than previously thought. A team of researchers from Germany's Max Planck Institute for Solar System Research, along with scientists from the universities of Münster and Göttingen, has provided the most accurate measurement of silicon dioxide on Mercury’s surface so far. Their findings, published in the journal Planetary Research, indicate that silicon dioxide makes up about 37% of Mercury's surface material by mass — up to 25% less than earlier estimates. This new understanding could help scientists better understand how Mercury's crust formed. Christian Renggli, lead author of the study and head of the "Experimental Laboratory Magma Ocean" research group at the Max Planck Institute, explained that the findings suggest that volcanic rocks on Mercury may have formed from material that was melted deeper within the planet's mantle than previously assumed. This would mean that Mercury's geological history is more complex and dynamic than earlier models suggested. To determine the composition of Mercury's surface, the researchers created tiny glass beads in the laboratory, each with a precisely controlled amount of silicon dioxide. These beads were used to calibrate infrared measurements taken from the surfaces of Mercury and the Moon. The method was first tested on the Moon, where scientists have access to both detailed remote sensing data and actual rock samples collected during past missions. NASA's Lunar Reconnaissance Orbiter has been gathering high-resolution infrared data from the Moon since 2009, helping to validate this technique. Using the same method, the researchers applied their calibration to Mercury, analyzing infrared observations collected from Earth. These included data from the Bok Telescope at Steward Observatory in Arizona. The results led to the conclusion that Mercury's surface contains about 37% silicon dioxide, significantly less than previously thought. This new data could reshape our understanding of Mercury's geological evolution. The European Space Agency's BepiColombo mission, set to arrive at Mercury in November of this year, may offer even more precise confirmation of these findings. The mission includes two separate probes, one provided by ESA and the other by Japan's JAXA. Once in orbit, the MERTIS instrument aboard BepiColombo will collect high-resolution infrared measurements of Mercury's surface. MERTIS was developed by the German Aerospace Center (DLR) in collaboration with the Institute for Planetology at the University of Münster, and it is expected to provide more detailed insights into Mercury's composition and geological history.