 Ida 's reflection spectrum was measured on 16 September 1980 by astronomers David J. Tholen and Edward F. Tedesco as part of the eight @-@ color asteroid survey ( <unk> ) . Its spectrum matched those of the asteroids in the S @-@ type classification . Many observations of Ida were made in early 1993 by the US Naval Observatory in Flagstaff and the Oak Ridge Observatory . These improved the measurement of Ida 's orbit around the Sun and reduced the uncertainty of its position during the Galileo flyby from 78 to 60 km ( 48 to 37 mi ) . 
