66 Maja and 951 Gaspra: Possible flyby targets for Cassini and Galileo missions

Abstract

The asteroids 66 Maja and 951 Gaspra, identified as possible flyby targets for Cassini and Galileo space missions, respectively, were observed during their apparitions in 1988. 66 Maja, a C-class asteroid with a diameter of 78 km, became the focus of a coordinated observing program carried out at Torino, Teramo, and Pic du Midi observatories using both photoelectric and CCD photometry. The computed synodic rotational period of Maja is 9.733 hr and the amplitude of the light variation was 0.45 mag. 951 Gaspra, an S-class asteroid with a diameter of 15 km, was observed about 2 months after opposition for two nights at the European Southern Observatory (La Silla, Chile) in August 1988. The best fit of the composite lightcurve was obtained with a rotational period of7.09 hr and a lightcurve amplitude of about 1.0 mag. An international program to coordinate Earth-based observations during the next oppositions of these asteroids is proposed.