The NEO (175706) 1996 FG3 in the 2–4 μm spectral region: Evidence for an aqueously altered surface

Abstract

We present observations of the binary near-Earth Asteroid (175706) 1996 FG3 in the 2–4μm spectral region, obtained on multiple nights using the SpeX instrument on the NASA Infrared Telescope Facility (IRTF). We find evidence for an absorption band of ∼5–10% (depending on the night and details of continuum choice), diagnostic for hydrated/hydroxylated minerals on the asteroid surface. This demonstrates that the optical surface of 1996 FG3 has not been heated to dehydrating temperatures. Sample-return missions targeting 1996 FG3 will likely find relatively fresh areas for sampling.