Ejecta Exchange, Color Evolution in the Pluto System, and Implications for KBOs and Asteroids with Satellites

TL;DR

This study investigates how impact ejecta exchange among Kuiper Belt objects and satellites influences their surface properties, revealing that ejecta can cause color and albedo similarities, especially among smaller bodies without atmospheric masking.

Contribution

It demonstrates that impact ejecta exchange can significantly alter surface characteristics of Kuiper Belt binaries and asteroids, a process not previously well understood.

Findings

Ejecta velocities from KB impacts are insufficient to escape Pluto and Charon.

Ejecta can escape Nix and Hydra, leading to surface exchange.

Color and albedo similarities develop among bodies due to ejecta exchange.

Abstract

We examine the ability of impacts by Kuiper Belt debris to cause regolith exchange between objects in the Pluto system. We find that ejecta velocities from KB impacts are too low to escape from Pluto and Charon. However, ejecta can escape Nix and Hydra, and is capable of covering one another to depths as high as 10s of meters, and Charon and Pluto, perhaps to depths up to several 10s of cm. Although Pluto's annual atmospheric frost deposition cycle will cover such imported debris on timescales faster than it is emplaced, no such masking mechanism is available on Hydra, Nix, and Charon. As a result, ejecta exchange between these bodies is expected to evolve their colors, albedos, and other photometric properties to be similar. We examined the ability of ejecta exchange to work for other Kuiper Belt binaries and found the process can be effective in many cases. This process may also operate in asteroid binary systems.