Modeling orbital gamma-ray spectroscopy experiments at carbonaceous asteroids.

Area of Science:

• Planetary Science
• Astrochemistry
• Spectroscopy

Background:

• Carbonaceous meteorites offer clues to early solar system composition.
• Orbital measurements are crucial for understanding asteroid and comet parent bodies.
• Surface layers can obscure the true bulk composition of celestial bodies.

Purpose of the Study:

• To assess the feasibility of using orbital gamma-ray spectroscopy (GRS) to determine bulk compositional differences among carbonaceous meteorite parent bodies.
• To simulate the performance of a GRS experiment in a Dawn-like orbit around model asteroids.

Main Methods:

• Performance simulation of an orbital GRS experiment.
• Modeling of asteroid gamma-ray spectra and spacecraft background flux using MCNPX Monte Carlo code.
• Analysis of GRS sensitivity to subsurface depths (20-50 cm).

Main Results:

• Achievable 3σ uncertainties under 1 wt% for key elements (H, C, O, Si, S, Fe, Cl).
• Demonstrated ability to measure compositions beneath surface layers.
• Calculated uncertainties are smaller than compositional differences between carbonaceous chondrite subclasses.

Conclusions:

• Orbital GRS is a feasible technique for characterizing bulk compositions of carbonaceous meteorite parent bodies.
• The study validates the use of heritage GRS designs for future asteroid missions.
• GRS can differentiate between various carbonaceous chondrite subclasses, enhancing our understanding of solar system formation.