New Delhi, Sept. 15 -- Scientists from the German Aerospace Center's Institute of Space Research reported Thursday that Mercury's shrinkage may be 30% greater than previously believed - a loss in diameter of as much as 14 miles (23 kilometers). That's significant for a planet barely 3,000 miles (4,900 kilometers) across.

Mercury's rough surface, continually reshaped by debris hurled from impact craters, may have hidden the true extent of the loss, according to the researchers whose findings appear in the journal Geophysical Research Letters.

The news comes one week after a pair of European and Japanese spacecraft shed its cruising platform and advanced toward Mercury. Known as BepiColombo, the linked craft are expected to enter orbit ar...