Self-Assembling Ice Membranes on Europa: Brinicle Properties, Field Examples, and Possible Energetic Systems in Icy Ocean Worlds

TL;DR

This paper explores the formation and properties of brinicle-like ice structures in icy ocean worlds like Europa, suggesting they could host ecosystems and influence chemical processes relevant to life's emergence.

Contribution

It introduces the concept that brinicle structures could form in extraterrestrial icy oceans, affecting chemistry and potential habitability in ways previously unconsidered.

Findings

Sulfate likely fractionates out of accreting ice on Europa and Enceladus.

Brinicles could serve as habitats for extraterrestrial ecosystems.

Endogenous sulfate may exist in Europa's ocean despite surface observations.

Abstract

Brinicles are self-assembling tubular ice membrane structures, centimeters to meters in length, found beneath sea ice in the polar regions of Earth. We discuss how the properties of brinicles make them of possible importance for chemistry in cold environments-including that of life's emergence-and we consider their formation in icy ocean world. We argue that the non-ice composition of the ice on Europa and Enceladus will vary spatially due to thermodynamic and mechanical properties that serve to separate and fractionate brines and solid materials. The specifics of the composition and dynamics of both the ice and the ocean in these worlds remain poorly constrained. We demonstrate through calculations using FREZCHEM that sulfate likely fractionates out of accreting ice in Europa and Enceladus, and thus that an exogenous origin of sulfate observed on Europa's surface need not preclude additional endogenous sulfate in Europa's ocean. We suggest that, like hydrothermal vents on Earth, brinicles in icy ocean worlds constitute ideal places where ecosystems of organisms might be found.