TY - JOUR
T1 - Closing the gap between Earth-based and interplanetary mission observations
T2 - Vesta seen by VLT/SPHERE
AU - Fétick, R. J.L.
AU - Jorda, L.
AU - Vernazza, P.
AU - Marsset, M.
AU - Drouard, A.
AU - Fusco, T.
AU - Carry, B.
AU - Marchis, F.
AU - Hanuš, J.
AU - Viikinkoski, M.
AU - Birlan, M.
AU - Bartczak, P.
AU - Berthier, J.
AU - Castillo-Rogez, J.
AU - Cipriani, F.
AU - Colas, F.
AU - Dudziński, G.
AU - Dumas, C.
AU - Ferrais, M.
AU - Jehin, E.
AU - Kaasalainen, M.
AU - Kryszczynska, A.
AU - Lamy, P.
AU - Le Coroller, H.
AU - Marciniak, A.
AU - Michalowski, T.
AU - Michel, P.
AU - Mugnier, L. M.
AU - Neichel, B.
AU - Pajuelo, M.
AU - Podlewska-Gaca, E.
AU - Santana-Ros, T.
AU - Tanga, P.
AU - Vachier, F.
AU - Vigan, A.
AU - Witasse, O.
AU - Yang, B.
N1 - Publisher Copyright:
© 2019 R. JL. Fétick et al.
PY - 2019/3/1
Y1 - 2019/3/1
N2 - Context. Over the past decades, several interplanetary missions have studied small bodies in situ, leading to major advances in our understanding of their geological and geophysical properties. These missions, however, have had a limited number of targets. Among them, the NASA Dawn mission has characterised in detail the topography and albedo variegation across the surface of asteroid (4) Vesta down to a spatial resolution of ~20 m pixel-1 scale. Aims. Here our aim was to determine how much topographic and albedo information can be retrieved from the ground with VLT/SPHERE in the case of Vesta, having a former space mission (Dawn) providing us with the ground truth that can be used as a benchmark. Methods. We observed Vesta with VLT/SPHERE/ZIMPOL as part of our ESO large programme (ID 199.C-0074) at six different epochs, and deconvolved the collected images with a parametric point spread function (PSF). We then compared our images with synthetic views of Vesta generated from the 3D shape model of the Dawn mission, on which we projected Vesta's albedo information. Results. We show that the deconvolution of the VLT/SPHERE images with a parametric PSF allows the retrieval of the main topographic and albedo features present across the surface of Vesta down to a spatial resolution of ~20-30 km. Contour extraction shows an accuracy of ~1 pixel (3.6 mas). The present study provides the very first quantitative estimate of the accuracy of ground-based adaptive-optics imaging observations of asteroid surfaces. Conclusions. In the case of Vesta, the upcoming generation of 30-40 m telescopes (ELT, TMT, GMT) should in principle be able to resolve all of the main features present across its surface, including the troughs and the north-south crater dichotomy, provided that they operate at the diffraction limit.
AB - Context. Over the past decades, several interplanetary missions have studied small bodies in situ, leading to major advances in our understanding of their geological and geophysical properties. These missions, however, have had a limited number of targets. Among them, the NASA Dawn mission has characterised in detail the topography and albedo variegation across the surface of asteroid (4) Vesta down to a spatial resolution of ~20 m pixel-1 scale. Aims. Here our aim was to determine how much topographic and albedo information can be retrieved from the ground with VLT/SPHERE in the case of Vesta, having a former space mission (Dawn) providing us with the ground truth that can be used as a benchmark. Methods. We observed Vesta with VLT/SPHERE/ZIMPOL as part of our ESO large programme (ID 199.C-0074) at six different epochs, and deconvolved the collected images with a parametric point spread function (PSF). We then compared our images with synthetic views of Vesta generated from the 3D shape model of the Dawn mission, on which we projected Vesta's albedo information. Results. We show that the deconvolution of the VLT/SPHERE images with a parametric PSF allows the retrieval of the main topographic and albedo features present across the surface of Vesta down to a spatial resolution of ~20-30 km. Contour extraction shows an accuracy of ~1 pixel (3.6 mas). The present study provides the very first quantitative estimate of the accuracy of ground-based adaptive-optics imaging observations of asteroid surfaces. Conclusions. In the case of Vesta, the upcoming generation of 30-40 m telescopes (ELT, TMT, GMT) should in principle be able to resolve all of the main features present across its surface, including the troughs and the north-south crater dichotomy, provided that they operate at the diffraction limit.
KW - Methods: observational
KW - Minor planets, asteroids: individual: Vesta
KW - Techniques: high angular resolution
KW - Techniques: image processing
UR - http://www.scopus.com/inward/record.url?scp=85062791633&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/201834749
DO - 10.1051/0004-6361/201834749
M3 - Article
AN - SCOPUS:85062791633
SN - 0004-6361
VL - 623
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
M1 - A6
ER -