Title: Variegation and space weathering on asteroid 21 Lutetia,
Abstract: During the flyby in 2010, the OSIRIS camera on-board Rosetta acquired
hundreds of high-resolution images of asteroid Lutetia's surface through a
range of narrow-band filters. While Lutetia appears very bland in the visible
wavelength range, Magrin et al. (2012) tentatively identified UV color
variations in the Baetica cluster, a group of relatively young craters close to
the north pole. As Lutetia remains a poorly understood asteroid, such color
variations may provide clues to the nature of its surface. We take the color
analysis one step further. First we orthorectify the images using a shape model
and improved camera pointing, then apply a variety of techniques (photometric
correction, principal component analysis) to the resulting color cubes. We
characterize variegation in the Baetica crater cluster at high spatial
resolution, identifying crater rays and small, fresh impact craters. We argue
that at least some of the color variation is due to space weathering, which
makes Lutetia's regolith redder and brighter.