  Ground-based characterization of spacecraft targets prior to mission
operations is critical to properly plan and execute measurements. Understanding
surface properties, like mineralogical composition and phase curves (expected
brightness at different viewing geometries) informs data acquisition during the
flybys. Binary near-Earth asteroids (NEA) (35107) 1991 VH and (175706) 1996 FG3
were selected as potential targets of the National Aeronautics and Space
Administration's (NASA) dual spacecraft Janus mission. We observed 1991 VH
using the 3-m NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii, on
July 26, 2008. 1996 FG3 was observed with the IRTF for seven nights during the
spring of 2022. Compositional analysis of 1991 VH revealed that this NEA is
classified as an Sq-type in the Bus-DeMeo taxonomy classification, with a
composition consistent with LL ordinary chondrites. Using thermal modeling, we
computed the thermally corrected spectra for 1996 FG3 and the corresponding
best fit albedo of about 2-3% for the best spectra averaged for each night. Our
spectral analysis indicates that this NEA is a Ch-type. The best possible
meteorite analogs for 1996 FG3, based on curve matching, are two carbonaceous
chondrites, Y-86789 and Murchison. No rotational variation was detected in the
spectra of 1996 FG3, which means there may not be any heterogeneities on the
surface of the primary. However, a clear phase reddening effect was observed in
our data, confirming findings from previous ground-based studies.
