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Updated: May 28, 2026

Scattering And Absorption of Light in Planetary Regoliths
Published on: July 1, 2019
Asteroid 21 Lutetia: low mass, high density
M Pätzold1, T P Andert, S W Asmar
1Rheinisches Institut für Umweltforschung, Abteilung Planetenforschung, an der Universität zu Köln, 50931 Cologne, Germany. martin.paetzold@uni-koeln.de
Abstract:
Asteroid 21 Lutetia was approached by the Rosetta spacecraft on 10 July 2010. The additional Doppler shift of the spacecraft radio signals imposed by 21 Lutetia's gravitational perturbation on the flyby trajectory were used to determine the mass of the asteroid. Calibrating and correcting for all Doppler contributions not associated with Lutetia, a least-squares fit to the residual frequency observations from 4 hours before to 6 hours after closest approach yields a mass of (1.700 ± 0.017) × 10(18) kilograms. Using the volume model of Lutetia determined by the Rosetta Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) camera, the bulk density, an important parameter for clues to its composition and interior, is (3.4 ± 0.3) × 10(3) kilograms per cubic meter.
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