Mercury shrank its radius by up to 38 km since its formation, contracting at a faster pace than earlier measurements recorded. Fresh evaluations of orbital data gathered by NASA MESSENGER probe confirmed the accelerated dimensional loss across the solar system’s innermost world.
Internal cooling reshapes the chemical surface of Mercury
Structural changes across the planetary crust manifest as distinct wrinkle ridges formed directly by thermal contraction. Planetary cooling drives this process. This thermal decline forced the outer rocky shell to fracture and buckle under persistent compressional stress.
Previous planetary models estimated a radius reduction of 2.7 km per billion years, yet updated calculations demonstrate a rate 10 to 30 percent faster, stripping away an additional 11 km to reach a total shrinkage of 38 km over billions of years.
According to Gaku Nishiyama from the German Aerospace Center, the planetary core contains a smaller fraction of lighter elements alongside a significantly larger solid interior and higher primordial temperatures than previous geological models assumed for the planet. “This result suggests that the interior of Mercury is even more unusual than we thought,” the researcher stated.
Dense impact craters across the terrain severely hinder the visual identification of these tectonic ridges. Ridge formations span across multiple geographic regions on the surface. Topographic imagery acquired by the MESSENGER spacecraft verified the extensive distribution of these compressed geological faults.
The joint BepiColombo mission will enter planetary orbit in the coming months, utilizing an advanced laser altimeter to measure surface elevation and evaluate the exact scale of crustal wrinkling. “Data from the BepiColombo mission will provide a more detailed picture and confirm the current results,” Nishiyama explained.
The scientific study, built on completed NASA mission records alongside incoming measurements from the European-Japanese BepiColombo probe, appeared in the journal Geophysical Research Letters.