Energy Dissipation in Synchronous Binary Asteroids

TL;DR

This paper models energy dissipation in synchronous binary asteroids, revealing how system configurations and material properties influence libration damping and orbital evolution, which is crucial for asteroid impact assessment and deflection strategies.

Contribution

It introduces a numeric model to analyze energy dissipation in binary asteroids, highlighting the effects of libration, eccentricity, and material stiffness on their long-term dynamics.

Findings

Tumbling within the synchronous state affects short-term libration damping.

Damping rates depend on the secondary's stiffness.

Hera can potentially measure libration damping to infer tidal properties.

Abstract

Synchronous binary asteroids can experience libration about their tidally-locked equilibrium, which will result in energy dissipation. This is an important topic to the Asteroid Impact and Deflection Assessment, where excitation caused by the DART kinetic impact in the Didymos binary asteroid system may be reduced through dissipation before Hera arrives to survey the effects of the impact. We develop a numeric model for energy dissipation in binary asteroids to explore how different system configurations affect the rate of energy dissipation. We find tumbling within the synchronous state eliminates a systematic trend in libration damping on short timescales (several years), but not over long times (hundreds of years) depending on the material conditions. Furthermore, damping of libration, eccentricity, and fluctuations in the semimajor axis are primarily dependent on the stiffness of the secondary, whereas the semimajor axis secular expansion rate is dictated by the stiffness of the primary, as expected. Systems experiencing stable planar libration in the secondary can see a noticeable reduction in libration amplitude after only a few years depending on the stiffness of the secondary, and thus dissipation should be considered during Hera's survey of Didymos. For a very dissipative secondary undergoing stable libration, Hera may be able to calculate the rate of libration damping in Dimorphos and therefore constrain its tidal parameters.