OSIRIS-REx Data Reveals Significant Surface Heterogeneity Across Asteroid Bennu
A new analysis of remote sensing data from NASA's OSIRIS-REx mission quantifies compositional and physical variations across four candidate sampling sites on asteroid Bennu using visible-near infrared and thermal infrared spectra. The study identifies statistically significant differences in hydration state, silicate composition, and mineral abundance across sites at 2-10 meter scales. These findings provide a spectral baseline for interpreting the asteroid sample returned by OSIRIS-REx and reveal how Bennu's surface preserves evidence of its alteration history.
Researchers analyzed spatially resolved spectroscopic data collected by OSIRIS-REx across four candidate sampling sites on asteroid (101955) Bennu—Nightingale, Osprey, Sandpiper, and Kingfisher—to characterize surface heterogeneity on the roughly 500-meter-radius body. Using visible-near infrared and thermal infrared spectra, the team derived diagnostic band parameters to assess compositional and physical variability. While visible-near infrared spectra showed similar overall reflectance shapes, systematic differences emerged in spectral slopes and the 2.74 micron OH absorption feature. Thermal infrared data revealed statistically significant shifts in silicate composition indicators, hydration state, and magnesium-to-iron ratios. Principal component and K-means clustering analyses separated each site into distinct spectral clusters, with statistical tests confirming that inter-site variations are significant. The Nightingale site, where OSIRIS-REx collected its sample, encompasses the full range of spectral properties observed across all four sites, making it representative of Bennu's broader compositional diversity.
What's missing
The study does not discuss implications for understanding Bennu's parent body or the broader context of carbonaceous asteroid aqueous alteration processes. Additionally, the paper does not address how these remote sensing results compare to or will be validated by direct laboratory analysis of the returned sample material.
What different sources said
- arXiv astro-phCenter
Quantifying Surface Heterogeneity Across Asteroid (101955) Bennu using Candidate Site Remote Sensing Data
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