 Ida was visited in 1993 by the Jupiter @-@ bound space probe Galileo . Its encounters of the asteroids Gaspra and Ida were secondary to the Jupiter mission . These were selected as targets in response to a new NASA policy directing mission planners to consider asteroid flybys for all spacecraft crossing the belt . No prior missions had attempted such a flyby . Galileo was launched into orbit by the Space Shuttle Atlantis mission STS @-@ 34 on 18 October 1989 . Changing Galileo 's trajectory to approach Ida required that it consume 34 kg ( 75 lb ) of propellant . Mission planners delayed the decision to attempt a flyby until they were certain that this would leave the spacecraft enough propellant to complete its Jupiter mission . 
