HAL : hal-00685136, version 1

arXiv : 1112.5944

Code Bibliographique ADS : 2011arXiv1112.5944C

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Shape modeling technique KOALA validated by ESA Rosetta at (21) Lutetia

Benoît Carry 1, Mikko Kaasalainen 2, William J. Merline 3, Thomas G. Müller 4, Laurent Jorda 5, Jack D. Drummond 6, Jérôme Berthier 7, Laurence O'Rourke 1, Josef Durech 8, Michael Küppers 1, Albert Conrad 9, Peter Tamblyn 3, Cécile Dumas 10, Holger Sierks 11, The Osiris Team

(27/12/2011)

We present a comparison of our results from ground-based observations of asteroid (21) Lutetia with imaging data acquired during the flyby of the asteroid by the ESA Rosetta mission. This flyby provided a unique opportunity to evaluate and calibrate our method of determination of size, 3-D shape, and spin of an asteroid from ground-based observations. We present our 3-D shape-modeling technique KOALA which is based on multi-dataset inversion. We compare the results we obtained with KOALA, prior to the flyby, on asteroid (21) Lutetia with the high-spatial resolution images of the asteroid taken with the OSIRIS camera on-board the ESA Rosetta spacecraft, during its encounter with Lutetia. The spin axis determined with KOALA was found to be accurate to within two degrees, while the KOALA diameter determinations were within 2% of the Rosetta-derived values. The 3-D shape of the KOALA model is also confirmed by the spectacular visual agreement between both 3-D shape models (KOALA pre- and OSIRIS post-flyby). We found a typical deviation of only 2 km at local scales between the profiles from KOALA predictions and OSIRIS images, resulting in a volume uncertainty provided by KOALA better than 10%. Radiometric techniques for the interpretation of thermal infrared data also benefit greatly from the KOALA shape model: the absolute size and geometric albedo can be derived with high accuracy, and thermal properties, for example the thermal inertia, can be determined unambiguously. We consider this to be a validation of the KOALA method. Because space exploration will remain limited to only a few objects, KOALA stands as a powerful technique to study a much larger set of small bodies using Earth-based observations.

1 :	European Space Astronomy Centre
	European Space Astronomy Centre
2 :	Department of Mathematics
	Tampere University of Technology
3 :	Southwest Research Institute
	Southwest Research Institute
4 :	Max-Planck-Institut für extraterrestrische Physik (MPE)
	Max-Planck-Institut
5 :	Laboratoire d'Astrophysique de Marseille (LAM)
	CNRS : UMR6110 – INSU – Université de Provence - Aix-Marseille I
6 :	Starfire Optical range
	Air Force Laboratory
7 :	Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE)
	CNRS : UMR8028 – INSU – Observatoire de Paris – Université Pierre et Marie Curie [UPMC] - Paris VI – Université Lille I - Sciences et technologies
8 :	Astronomical Institute
	Charles University Prague, Faculty of Mathematics and Physics
9 :	Max Planck Institut für Astronomie (MPIA)
	Max Planck Institut für Astronomie
10 :	European Southern Observatory (ESO)
	ESO
11 :	Max-Planck-Institut für Sonnensystemforschung
	Max-Planck-Institut für sonnensystemforschung

Domaine

:

Physique/Astrophysique/Planétologie et astrophysique de la terre Planète et Univers/Astrophysique/Planétologie et astrophysique de la terre

Mots Clés : Astrophysics – Earth and Planetary Astrophysics

hal-00685136, version 1

http://hal.archives-ouvertes.fr/hal-00685136

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Contributeur : Benoît Carry <>

Soumis le : Mercredi 4 Avril 2012, 11:28:48

Dernière modification le : Mercredi 4 Avril 2012, 11:28:48