Study Finds Mercury May Be Shrinking Faster Than Previously Estimated
Researchers say Mercury's diameter could be decreasing by up to 14 miles, about 30% more than earlier estimates, based on new analysis of surface features.
Scientists from the German Aerospace Center’s Institute of Space Research reported that Mercury may be losing as much as 14 miles from its diameter, roughly 30% more than earlier calculations suggested. The findings, published in Geophysical Research Letters, indicate that the planet’s rough, crater-filled surface may have concealed the full extent of the contraction.
Lead author Gaku Nishiyama, who is also part of the European-Japanese BepiColombo mission, said the spacecraft’s laser instrument, scheduled to begin orbiting Mercury in November, should verify the degree of shrinkage caused by internal cooling. The new estimate exceeds measurements taken by NASA’s Messenger probe in the 2010s.
Mercury’s iron-rich core has been cooling and contracting since the planet formed 4.5 billion years ago, causing the mantle and crust to compress. By comparing fault maps with newer surface-roughness maps, the team found that the roughest areas showed fewer visible contraction features, suggesting that impact debris may have buried some of the planet’s shrinkage wrinkles.
Nishiyama said the revised figures could improve understanding of other bodies undergoing similar contraction. > "We are quite excited," he wrote, adding that the work brings scientists closer to a realistic picture of Mercury’s evolution.