Limits of Life and the Habitability of Mars: The ESA Space Experiment BIOMEX on the ISS

TLDR

BIOMEX is an ESA/Roscosmos space exposure experiment on the ISS, launched by an international consortium of 30 institutes across 12 countries and 3 continents. The study aims to develop a scalable concept for future lunar exposure experiments and to serve as a low‑Earth‑orbit pretest. Researchers embedded lichens, archaea, bacteria, cyanobacteria, snow/permafrost algae, black fungi, and bryophytes in mixtures of Martian and lunar regolith analogs or terrestrial minerals, then exposed them to space and simulated Mars‑like conditions using the EXPOSE‑R2 facility to assess biosignature stability and degradation. The experiments yielded the first data on the viability of these organisms under space and Mars‑like conditions, informing assessments of Mars habitability, limits of life, and the plausibility of lithopanspermia, and included comprehensive preflight, ground‑simulation, and postflight analyses.

Abstract

BIOMEX (BIOlogy and Mars EXperiment) is an ESA/Roscosmos space exposure experiment housed within the exposure facility EXPOSE-R2 outside the Zvezda module on the International Space Station (ISS). The design of the multiuser facility supports—among others—the BIOMEX investigations into the stability and level of degradation of space-exposed biosignatures such as pigments, secondary metabolites, and cell surfaces in contact with a terrestrial and Mars analog mineral environment. In parallel, analysis on the viability of the investigated organisms has provided relevant data for evaluation of the habitability of Mars, for the limits of life, and for the likelihood of an interplanetary transfer of life (theory of lithopanspermia). In this project, lichens, archaea, bacteria, cyanobacteria, snow/permafrost algae, meristematic black fungi, and bryophytes from alpine and polar habitats were embedded, grown, and cultured on a mixture of martian and lunar regolith analogs or other terrestrial minerals. The organisms and regolith analogs and terrestrial mineral mixtures were then exposed to space and to simulated Mars-like conditions by way of the EXPOSE-R2 facility. In this special issue, we present the first set of data obtained in reference to our investigation into the habitability of Mars and limits of life. This project was initiated and implemented by the BIOMEX group, an international and interdisciplinary consortium of 30 institutes in 12 countries on 3 continents. Preflight tests for sample selection, results from ground-based simulation experiments, and the space experiments themselves are presented and include a complete overview of the scientific processes required for this space experiment and postflight analysis. The presented BIOMEX concept could be scaled up to future exposure experiments on the Moon and will serve as a pretest in low Earth orbit.