The Optical, Spectroscopic, and Infrared Remote Imaging System OSIRIS was already used to observe the light curve of the E-type asteroid (2867) Steins in preparation of the ESA Rosetta flyby (Küppers et al. A&A 2007). During the approach observations of the light curve will be repeated to improve the knowledge about the rotational status, coarse shape, and phase of Steins. The closest approach (CA) campaign will start 2 hours before CA when the spacecraft is still 60000 km away from the asteroid. Changes of the reflectivity while passing through zero phase angle shortly before CA will be recorded taking images as fast as possible. The wide angle camera (WAC) will be used to search for satellites. Boulders as small as 10 cm in diameter can be detected in the large field of view. The narrow angle camera (NAC) will concentrate to observe the properties of Steins determining its shape and surface morphology. Near CA at a distance of 800 km images of Steins will cover about 330 pixel in diameter out of the 2k by 2k pixel CCD. We will report on the topography and geomorphology based on a derived digital terrain model. Photometric properties and phase angle variations will be determined over taking advantage of the varying observation geometry. Both cameras will use a complement of 23 filters between 245 to 1000 nm.
The Rosetta Asteroid Steins Flyby Observed by OSIRIS
BARBIERI, CESARE;
2008
Abstract
The Optical, Spectroscopic, and Infrared Remote Imaging System OSIRIS was already used to observe the light curve of the E-type asteroid (2867) Steins in preparation of the ESA Rosetta flyby (Küppers et al. A&A 2007). During the approach observations of the light curve will be repeated to improve the knowledge about the rotational status, coarse shape, and phase of Steins. The closest approach (CA) campaign will start 2 hours before CA when the spacecraft is still 60000 km away from the asteroid. Changes of the reflectivity while passing through zero phase angle shortly before CA will be recorded taking images as fast as possible. The wide angle camera (WAC) will be used to search for satellites. Boulders as small as 10 cm in diameter can be detected in the large field of view. The narrow angle camera (NAC) will concentrate to observe the properties of Steins determining its shape and surface morphology. Near CA at a distance of 800 km images of Steins will cover about 330 pixel in diameter out of the 2k by 2k pixel CCD. We will report on the topography and geomorphology based on a derived digital terrain model. Photometric properties and phase angle variations will be determined over taking advantage of the varying observation geometry. Both cameras will use a complement of 23 filters between 245 to 1000 nm.Pubblicazioni consigliate
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