Apsidal Precession in Binary Asteroids

TL;DR

This paper investigates how the shape and spin of the secondary in binary asteroids influence the precession of their orbits, revealing reshaping effects from impacts and potential chaotic orbital evolution.

Contribution

It introduces a numerical method to analyze the impact of secondary's shape and spin on apsidal precession, with application to the Didymos system and DART impact effects.

Findings

Dimorphos was likely reshaped and elongated after DART impact.

Non-principal axis rotation can cause chaotic orbital evolution.

The secondary's properties significantly affect orbital precession.

Abstract

While the secondary in a binary asteroid plays an important role in the precession of the mutual orbit, this role has not been thoroughly studied. Given the complex spin-orbit coupled dynamics in binary asteroids, we use a numerical approach to study the relationship between the secondary's shape and spin and the apsidal precession rate of the orbit. Using this approach in conjunction with observations of Didymos, we find it is likely that Dimorphos was significantly reshaped as a result of the DART impact, with its new shape more elongated than the pre-impact shape. Finally, we show that non-principal axis rotation of the secondary can lead to a chaotic evolution of the longitude of the periapsis.