B. Carry, M. Kaasalainen, W. J. Merline, T. G. Müller, L. Jorda, J. D. Drummond, J. Berthier, L. O'Rourke, J. Durech, M. Küppers, A. Conrad, P. Tamblyn, C. Dumas, H. Sierks, the OSIRIS Team
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.
View original:
http://arxiv.org/abs/1112.5944
No comments:
Post a Comment