Mercury Contracted 10–30% More Than Estimated, Study Finds

A study published in the Geophysical Research Letters, using NASA's MESSENGER spacecraft data, estimated Mercury shrank 10–30% more than earlier calculations.

• The study, published in the journal Geophysical Research Letters, drew on surface maps from NASA's MESSENGER spacecraft, which orbited Mercury from 2011 to 2015.
• The team reanalyzed five craters and concluded Mercury's cooling-driven contraction was 10–30% greater than earlier estimates, because rugged surface regions hide contraction structures.
• Lead author Gaku Nishiyama of the German Aerospace Center said the increase implies Mercury's core may be larger, contain fewer light elements, or have had a higher initial temperature.
• Nishiyama said the results may apply to the Moon and Mars, which could also still be contracting as heat escapes from their cores.