Strength In Diversity: Small Bodies as the Most Important Objects in Planetary Sciences

TL;DR

Small bodies in planetary science are highly diverse in composition, history, and physical properties, and understanding this diversity is crucial for advancing planetary science.

Contribution

The paper emphasizes the importance of recognizing the vast diversity of small bodies and advocates for sustained, diverse scientific efforts to study them.

Findings

Small bodies exhibit a wide range of compositions and histories.

Diversity in small bodies exceeds that of major planets.

Supporting varied missions enhances understanding of planetary formation.

Abstract

Small bodies, the unaccreted leftovers of planetary formation, are often mistaken for the leftovers of planetary science in the sense that they are everything else after the planets and their satellites (or sometimes just their regular satellites) are accounted for. This mistaken view elides the great diversity of compositions, histories, and present-day conditions and processes found in the small bodies, and the interdisciplinary nature of their study. Understanding small bodies is critical to planetary science as a field, and we urge planetary scientists and our decision makers to continue to support science-based mission selections and to recognize that while small bodies have been grouped together for convenience, the diversity of these objects in terms of composition, mass, differentiation, evolution, activity, dynamical state, physical structure, thermal environment, thermal history, and formation vastly exceeds the observed variability in the major planets and their satellites. Treating them as a monolithic group with interchangeable members does a grave injustice to the range of fundamental questions they address. We advocate for a deep and ongoing program of missions, telescopic observations, R and A funding, and student support that respects this diversity.