DellaGiustina, D. N., Burke, K. N., Walsh, K. J., Smith, P. H., Golish, D. R., Bierhaus, E. B., Ballouz, R. -L, Becker, T. L., Campins, H., Tatsumi, E., Yumoto, K., Sugita, S., Deshapriya, J. D. P., Cloutis, E. A., Clark, B. E., Hendrix, A. R., Sen, A., Al Asad, M. M., Daly, M. G., Applin, D. M., Avdellidou, C., Barucci, M. A., Becker, K. J., Bennett, C. A., Bottke, W. F. et al. 2020. "Variations in color and reflectance on the surface of asteroid (101955) Bennu." Science, https://doi.org/10.1126/science.abc3660.
Visible-wavelength color and reflectance provide information about the geologic history of planetary surfaces. We present multispectral images (0.44 to 0.89 microns) of near-Earth asteroid (101955) Bennu. The surface has variable colors overlain on a moderately blue global terrain. Two primary boulder types are distinguishable by their reflectance and texture. Space weathering of Bennu surface materials does not simply progress from red to blue (or vice versa). Instead, freshly exposed, redder surfaces initially brighten in the near-ultraviolet (become bluer at shorter wavelengths), then brighten in the visible to near-infrared, leading to Bennu's moderately blue average color. Craters indicate that the timescale of these color changes is ~10 5 years. We attribute the reflectance and color variation to a combination of primordial heterogeneity and varying exposure ages.
