In the DES field we enter the number of the asteroid or comet we want e.g. 99942 (if it is the asteroid Apophis or 12P if it is the comet 12P/Pons-Brooks), in the Date Min and Date Max fields we enter the dates we want (e.g. 1990-02-01 and 2040-10-01) and finally in the Dist Max field the closest distance we want to approach the Earth in A.U. ( 1 A.U.=149.597.871 km). Data provided by NASA.