Vital Signs: Seismology of ocean worlds

TL;DR

This paper explores the potential for seismic activity on ocean worlds covered with ice, highlighting their unique properties that could make seismic measurements feasible and valuable for understanding their habitability and internal structures.

Contribution

It introduces new considerations for seismic sources on icy ocean worlds and assesses their feasibility, suggesting they could provide critical insights into habitability and internal composition.

Findings

Seismic activity on ocean worlds should be frequent due to tidal fracturing.

Ice's ease of fracturing and energy dissipation enhances seismic detectability.

Lower thermal noise and lack of atmosphere simplify seismic measurements.

Abstract

Ice-covered ocean worlds possess diverse energy sources and associated mechanisms that are capable of driving significant seismic activity, but to date no measurements of their seismic activity have been obtained. Such investigations could probe their transport properties and radial structures, with possibilities for locating and characterizing trapped liquids that may host life and yielding critical constraints on redox fluxes, and thus on habitability. Modeling efforts have examined seismic sources from tectonic fracturing and impacts. Here, we describe other possible seismic sources, their associations with science questions constraining habitability, and the feasibility of implementing such investigations. We argue, by analogy with the Moon, that detectable seismic activity on tidally flexed ocean worlds should occur frequently. Their ices fracture more easily than rocks, and dissipate more tidal energy than the <1 GW of the Moon and Mars. Icy ocean worlds also should create less thermal noise for a due to their greater distance and consequently smaller diurnal temperature variations. They also lack substantial atmospheres (except in the case of Titan) that would create additional noise. Thus, seismic experiments could be less complex and less susceptible to noise than prior or planned planetary seismology investigations of the Moon or Mars.