Skip to main content# Tool to Constrain Tidal Effects of Binary Asteroids Using Thermal Modeling

Presentation #412.02 in the session Asteroids: Near-Earth Objects (Poster)

Published onOct 23, 2023

Tool to Constrain Tidal Effects of Binary Asteroids Using Thermal Modeling

**Introduction:** Asteroids are remnants of the protoplanetary disk that surrounded the Sun during solar system formation. Binary asteroids are systems in which the primary body has a satellite and they make up 15% of the Near Earth Asteroid population. Understanding the composition and dynamics of these systems helps to advance many areas of science and engineering, including solar system cosmochemical evolution and planetary deflection. Bulk density and tidal effects on binary asteroids are important parameters to determine but difficult to constrain. The presented method leverages a 3D thermophysical modelling tool by Sorli & Hayne [1] and a BYORP simulation tool by McMahon [2] to constrain these parameters. **Method:** A range of possible bulk density values, ρ ± σ can be obtained via orbit fitting [3] and fed into the thermal model. The output surface temperatures over time are used to compute the reaction forces acting on the secondary, which are used to compute the BYORP coefficient, a_{02,T} [4]. a_{02,T} is compared with a_{02,S}, which is the simulated BYORP coefficient of the body and computed using the BYORP simulation tool. The a_{02} value that is equal or closest to a_{02,S} is a validated a_{02} value and the corresponding ρ value used to obtain that a_{02,T} is the bulk density estimate. The validated a_{02,T} value is used to compute a corresponding semimajor axes change, a ̇_{BYORP}, which represents the effects on the mutual orbit due solely to the BYORP effect [5]. This a ̇_{BYORP} is compared to observed range of feasible a ̇_{obs} ± σ values to constrain tidal effects on the mutual orbit. **Application:** The tool will be validated on the 1996 FG3 system and used to constrain density and tides of the Didymos system. The validation and test case will both be presented. References: [1] Sorli, K. C. P. O., & Scheeres, D.J.(2022). Development of a Thermophysical Model for Binary Asteroid Systemsand Application to Janus Mission Target 1996 FG3. LPI Contributions, 2678 [2] J. W. McMahon, “Libration-eccentricity Evolution of Expansive Binary Asteroids in the Presence of Tidal Dissipation” ACM 2014, Finland [3] Naidu, S. P., Benner, L. A. M., Brozovic, M., Nolan, M. C., Ostro, S. J., Margot, J. L., ... & Jao, J. S. (2020). Radar observations and a physical model of binary near-Earth asteroid 65803 Didymos,target of the DART mission. Icarus, 348, 113777. [4] McMahon, J., & Scheeres, D. (2010). Detailed prediction for the BYORP effect on 1999 KW4 and implications for the binary population. Icarus, 209, 494–509. [5] Walsh, K. J., & Jacobson, S. A. (2015). Formation and evolution of binary asteroids. Asteroids IV, 2002