Mercury contraction may be 30% higher than previously estimated

New research published in Geophysical Research Letters suggests that the planet Mercury has contracted significantly more than previously estimated. Scientists believe the planet's contraction may be between 10% and 30% greater than prior measurements indicated, potentially resulting in a loss of up to 23 kilometers in diameter since its formation approximately 4.5 billion years ago.

A study led by Gaku Nishiyama of the German Aerospace Center (DLR) and Hokkaido University found that the planet's geological history of shrinking due to its cooling metallic core has been partially obscured. By comparing tectonic structure maps with surface roughness maps, researchers discovered that asteroid and comet impact debris has covered many of the ridges and scarps—planetary wrinkles created by contraction—particularly in the roughest regions of the planet.

This revised understanding of Mercury's radial contraction, which could be as much as 11.6 kilometers, provides critical data for refining models regarding the planet's chemical composition, thermal history, and the size of its enormous metallic core. Future observations from the BepiColombo mission are expected to provide further clarity on these small-scale tectonic features.