Evidence for the effects of space weathering spectral signatures on low albedo asteroids

Abstract

Context. Space weathering changes asteroid surfaces. We know from observations of the Moon and high-albedo asteroids that interplanetary surface processes can alter the spectral properties of silicates. The next step is to extend the study to primitive asteroids. This work supports the OSIRIS-REx mission by providing predictions for what space weathering effects we can expect to find on the mission target: asteroid (101955) 1999 RQ36.Aims. To investigate the possible spectral signatures of surface processes on carbonaceous (low-albedo) asteroids, we study the reflected light spectra of carbonaceous meteorites (assumed to represent asteroid subsurface materials) and compare them with telescopic reflected light spectra of asteroids (assumed to represent asteroid surface materials).Methods. In this work, we assume that primitive C-complex asteroids are the parent bodies of carbonaceous chondrites. We reason that differences between spectra of particulate samples of the meteorites and spectra of the regolith of asteroids can be due to either differences in textural properties, or differences caused by surface processes on the asteroid. We use telescopic observations of Ch/Cgh-type asteroids (0.4 to 2.4 μ m) and compare them statistically with 106 CM meteorite spectra from RELAB.Results. Our results indicate spectral blueing of asteroids, with little to no concurrent albedo change or band modification.