 Like all main @-@ belt asteroids , Ida 's orbit lies between the planets Mars and Jupiter . Its orbital period is 4 @.@ 84 years , and its rotation period is 4 @.@ 63 hours . Ida has an average diameter of 31 @.@ 4 km ( 19 @.@ 5 mi ) . It is irregularly shaped and elongated , and apparently composed of two large objects connected together . Its surface is one of the most heavily cratered in the Solar System , featuring a wide variety of crater sizes and ages . 
