Letter to the Editor

Pre-flyby estimates of the precision of the mass determination of asteroid (21) Lutetia from Rosetta radio tracking

¹ Rheinisches Institut für Umweltforschung, Abteilung Planetenforschung, an der Universität zu Köln, Aachener Strasse 209, 50931 Köln, Germany e-mail: Martin.Paetzold@uni-koeln.de
² Institut für Raumfahrttechnik, Universität der Bundeswehr München, Werner-Heisenberg-Weg 150, Neubiberg, Germany
³ Jet Propulsion Laboratory, California Institute for Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
⁴ Géosciences du Pacifique Sud, Université de la Polynésie française, BP 6570, 98702 FAA'A, Tahiti, Polynésie Française, France
⁵ Argelander Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany

Received: 26 February 2010
Accepted: 16 June 2010

Abstract

The Rosetta spacecraft will fly by its second target asteroid (21) Lutetia on 10 July 2010. Simulations based on the currently known size of Lutetia and assumptions on the bulk density show that tracking of two radio-carrier frequencies at X-band (8.4 GHz) and S-band (2.3 GHz) during the flyby will determine the mass at less than 1% accuracy. Derivation of the asteroid volume by camera observation will drive the uncertainty in derivation of the bulk density. Mass and bulk density provide valuable clues that might help resolve the difficulties in determining the taxonomic class of the asteroid.