Constraining the Interiors of Asteroids Through Close Encounters

Abstract

Knowledge of the interior density distribution of an asteroid can reveal its composition and constrain its evolutionary history. However, most asteroid observational techniques are not sensitive to interior properties. We investigate the interior constraints accessible through monitoring variations in angular velocity during a close encounter. We derive the equations of motion for a rigid asteroid's orientation and angular velocity to arbitrary order and use them to generate synthetic angular velocity data for a representative asteroid on a close Earth encounter. We develop a toolkit AIME (Asteroid Interior Mapping from Encounters) which reconstructs asteroid density distribution from these data, and we perform injection-retrieval tests on these synthetic data to assess AIME's accuracy and precision. We also perform a sensitivity analysis to asteroid parameters (e.g., asteroid shape and orbital elements), observational set-up (e.g., measurement precision and cadence), and the mapping models used. We find that high precision in rotational period estimates (<~0.27 seconds) are necessary for each cadence, and that low perigees (<~18 Earth radii) are necessary to resolve large-scale density non-uniformities to uncertainties ~0.1% of the local density under some models.

17 pages, 14 figures. This is a pre-copyedited, author-produced PDF of an article accepted for publication in MNRAS following peer review

References in corpus (4)

• Numerical predictions of surface effects during the 2029 close approach of asteroid 99942 Apophis
• Near-Earth Asteroid Satellite Spins Under Spin-Orbit Coupling
• Refinement of the convex shape model and tumbling spin state of (99942) Apophis using the 2020-2021 apparition data
• Observational Investigation of the 2013 Near-Earth Encounter by Asteroid (367943) Duende