Active moons in our Solar System and beyond -- Io, Europa, Enceladus, Triton, and exomoons

TL;DR

This review discusses active moons like Io, Europa, Enceladus, Triton, and exomoons, focusing on their signatures, origins, and potential for biosignature detection through observations and plumes.

Contribution

It provides a comprehensive overview of active moons' signatures, formation, and the potential for detecting biosignatures, including exomoons.

Findings

Io's plumes reach hundreds of kilometers high.

Exomoons could produce detectable signatures with ground-based telescopes.

Subsurface ocean plumes on Europa and Enceladus are prime candidates for biosignature detection.

Abstract

The outgassing signatures of Io, Europa, Enceladus, Triton, and Io-like exomoons are the focus of this review chapter. The rocky volcanic world of Io is unique in our Solar System, with plumes reaching to hundreds of kilometres in altitude. Io-like exomoons could leave signatures strong enough to be detected with ground-based telescopes. The icy moons Europa and Enceladus, with their subsurface oceans, are currently the best candidates for life. Triton is different in many ways and raises unexplored questions. Our knowledge of these active moons is derived from space- and ground-based observations. To understand their origin, we discuss moon formation in general, before examining evidence and signatures of plumes on these moons. Given the accessibility of subsurface oceanic material through the occurrence of plumes, we expand on possibilities to investigate biosignatures.