Reflectance of Asteroid 4179 Toutatis Based on Its Space Optical Image

On 13rd December 2012, the Chang'e-2 probe made a successful flyby of the asteroid 4179 Toutatis in deep space about 7 million kilometers away from the earth, and acquired a series of optical images with a high resolution better than 3 m. In this paper, we process the radiation calibration data of the imaging camera by the least squares fitting method, to obtain the relative calibration matrix and absolute calibration coefficients to correct the original asteroid images and calibration data, then to make inversion of the asteroid surface radiance at the imaging time. According to the Hapke's description about the application of the Nicodemus' definition of reflectance in the planetary science, the hemispherical albedo of Toutatis is obtained. The surface hemispherical albedos at the R, G, and B bands are 0.2083, 0.1269, and 0.1346, respectively, and the asteroid's mean surface hemispherical albedo is 0.1566. The results indicate that Toutatis is somewhat a red object in the visible spectral band.