C. R. Chapman P.C. Thomas M. E. Davies R. Greenberg K. Klaasen D. Byrnes L. D’Amario S. Synnott T. V. Johnson A. McEwen W.J. Merline D. R. Davis J. #NAME? Petit A. Storrs J. Veverka B. Zellner M. J. S. Belton 1995 <p><span>During its reconnaissance of the asteroid 243 Ida, the Galileo spacecraft returned images of a second object, 1993(243)1 Dactyl</span>¹<span>— the first confirmed satellite of an asteroid. Sufficient data were obtained on the motion of Dactyl to determine its orbit as a function of Ida's mass. Here we apply statistical and dynamical arguments to constrain the range of possible orbits, and hence the mass of Ida. Combined with the volume of Ida</span>²<span>, this yields a bulk density of 2.6 ± 0.5 g cm</span>⁻³<span>. Allowing for the uncertainty in the porosity of Ida, this density range is consistent with a bulk chon-dritic composition, and argues against some (but not all) classes of meteoritic igneous rock types that have been suggested as compositionally representative of S-type asteroids like Ida.</span></p> application/pdf 10.1038/374785a0 en Springer Nature Bulk density of asteroid 243 Ida from the orbit of its satellite Dactyl article