Phase Angle Dependent Ultraviolet to Far-Infrared (0.25-100 μm)
Reflectance Spectroscopy of Mukundpura (CM2) Meteorite: Potential
analogue of (162173) Ryugu and (101955) Bennu
Abstract
Specialized spectral library measured under controlled planetary surface
conditions is important to accurately derive the chemical and physical
properties from remote observations. It’s a general practice to powder
the planetary analogues during spectroscopy studies as most surfaces are
made up of fine-regolith materials. However, upon arrival at C-type
asteroids Ryugu and Bennu, Hayabusa2 and OSIRIS-REx revealed these
surfaces filled with rocks and boulders. In this study, we built a phase
angle dependent ultraviolet (UV) to far-infrared (FIR) spectroscopy
(0.2-100 µm) of a rocky piece of Mukundpura meteorite having five
surfaces including fusion crust. Mukundpura meteorite is the freshest
carbonaceous chondrite belonging to CM-chondrites in the entire
collection which fell in the desert village of India on June 6, 2017.
The two sets of varying viewing geometries having incident and
reflectance angles includes ; a) asymmetric viewing geometry at 13°-13°,
13°-20°, 13°-30°, 13°-40°, and 13°-50°, and b) symmetric viewing
geometry at 13°-13°, 20°-20°, 30°-30°, 40°-40°, and 50°-50°. This study
found that overall spectral shape, reflectance values, and band depth of
diagnostic absorption features are affected by viewing geometry and
surface roughness; however, the fundamental band centers are not
affected. The comparison of 2.72 µm absorption band of fusion crust and
fresh interiors of Mukundpura with published Ryugu and Bennu spectra
supports that Ryugu surface has experienced extensive heating in its
geologic past compared to Bennu. Overall study shows that fusion crust
and internal surfaces of the Mukundpura meteorite is a potential
analogue of Ryugu and Bennu both spectrally and morphologically.