Trans-Neptunian Space and the Post-Pluto Paradigm

TL;DR

This paper reviews what the Pluto system reveals about the origins, properties, and evolution of trans-Neptunian objects, including insights into their size distribution, satellite formation, and surface histories, guiding future research in the outer solar system.

Contribution

It synthesizes recent findings from the Pluto system to infer properties of small trans-Neptunian objects and discusses implications for their formation and evolution.

Findings

Inferred size distribution of small trans-Neptunian objects.

Estimated fraction of binary systems at small sizes.

Implications for satellite formation processes.

Abstract

The Pluto system is an archetype for the multitude of icy dwarf planets and accompanying satellite systems that populate the vast volume of the solar system beyond Neptune. New Horizons' exploration of Pluto and its five moons gave us a glimpse into the range of properties that their kin may host. Furthermore, the surfaces of Pluto and Charon record eons of bombardment by small trans-Neptunian objects, and by treating them as witness plates we can infer a few key properties of the trans-Neptunian population at sizes far below current direct-detection limits. This chapter summarizes what we have learned from the Pluto system about the origins and properties of the trans-Neptunian populations, the processes that have acted upon those members over the age of the solar system, and the processes likely to remain active today. Included in this summary is an inference of the properties of the size distribution of small trans-Neptunian objects and estimates on the fraction of binary systems present at small sizes. Further, this chapter compares the extant properties of the satellites of trans-Neptunian dwarf planets and their implications for the processes of satellite formation and the early evolution of planetesimals in the outer solar system. Finally, this chapter concludes with a discussion of near-term theoretical, observational, and laboratory efforts that can further ground our understanding of the Pluto system and how its properties can guide future exploration of trans-Neptunian space.