NUMBER@1 ORGANIZATION@1 is the second most massive object in the asteroid belt , with a mean diameter of about NUMBER@2 km and an estimated mass of NUMBER@3 % of the mass of the entire asteroid belt .

NUMBER@1 ORGANIZATION@1 -LRB- -RRB- is the second most massive asteroid in the solar system , with an average diameter of about NUMBER@2 km -LRB- around NUMBER@4 miles -RRB- and an estimated mass NUMBER@3 % the mass of the entire asteroid belt .
