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The space environment is regularly used for experiments addressing astrobiology research goals. The specific conditions prevailing in Earth orbit and beyond, notably the radiative environment (photons and energetic particles) and the possibility to conduct long-duration measurements, have been the main motivations for developing experimental concepts to expose chemical or biological samples to outer space, or to use the reentry of a spacecraft on Earth to simulate the fall of a meteorite. This paper represents an overview of past and current research in astrobiology conducted in Earth orbit and beyond, with a special focus on ESA missions such as Biopan, STONE (on Russian FOTON capsules) and EXPOSE facilities (outside the International Space Station). The future of exposure platforms is discussed, notably how they can be improved for better science return, and how to incorporate the use of small satellites such as those built in cubesat format.

This work was supported by the European Space Agency under the Topical Team, 'Geobiology in Space Exploration'. Claire Cousins is funded by a Royal Society of Edinburgh Research Fellowship, co-funded by the Marie Curie Actions FP7 Programme. Geobiology, and in particular mineral-microbe interactions, has a significant role to play in current and future space exploration. This includes the search for biosignatures in extraterrestrial environments, and the human exploration of space. Microorganisms can be exploited to advance such exploration, such as through biomining, maintenance of life-support systems, and testing of life-detection instrumentation. In view of these potential applications, a European Space Agency (ESA) Topical Team “Geobiology in Space Exploration” was developed to explore these applications, and identify research avenues to be investigated to support this endeavour. Through community workshops, a roadmap was produced, with which to define future research directions via a set of 15 recommendations spanning three key areas: Science, Technology, and Community. These roadmap recommendations identify the need for research into: (1) New terrestrial space-analogue environments; (2) Community level microbial-mineral interactions; (3) Response of biofilms to the space environment; (4) Enzymatic and biochemical mineral interaction; (5) Technical refinement of instrumentation for space-based microbiology experiments, including precursor flight tests; (6) Integration of existing ground-based planetary simulation facilities; (7) Integration of fieldsite biogeography with laboratory- and field-based research; (8) Modification of existing planetary instruments for new geobiological investigations; (9) Development of in situ sample preparation techniques; (10) Miniaturisation of existing analytical methods, such as DNA sequencing technology; (11) New sensor technology to analyse chemical interaction in small volume samples; (12) Development of reusable Lunar and Near Earth Object experimental platforms; (13) Utility of Earth-based research to enable the realistic pursuit of extraterrestrial biosignatures; (14) Terrestrial benefits and technological spin-off from existing and future space-based geobiology investigations; and (15) New communication avenues between space agencies and terrestrial research organisations to enable this impact to be developed. Postprint