The first measurements of the radiation dose on the lunar surface are reported in preparation for human exploration of the Moon.

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.

The role of DNA repair by nonhomologous-end joining (NHEJ) in spore resistance to UV, ionizing radiation, and ultrahigh vacuum was studied in wild-type and DNA repair mutants ( recA , splB , ykoU , ykoV , and ykoU ykoV mutants) of Bacillus subtilis . NHEJ-defective spores with mutations in ykoU , ykoV , and ykoU ykoV were significantly more sensitive to UV, ionizing radiation, and ultrahigh vacuum than wild-type spores, indicating that NHEJ provides an important pathway during spore germination for repair of DNA double-strand breaks.

Reitz, G., Berger, T., Bilski, P., Facius, R., Hajek, M., Petrov, V., Puchalska, M., Zhou, D., Bossler, J., Akatov, Y., Shurshakov, V., Olko, P., Ptaszkiewicz, M., Bergmann, R., Fugger, M., Vana, N., Beaujean, R., Burmeister, S., Bartlett, D., Hager, L., Pálfalvi, J., Szabó, J., O'Sullivan, D., Kitamura, H., Uchihori, Y., Yasuda, N., Nagamatsu, A., Tawara, H., Benton, E., Gaza, R., McKeever, S., Sawakuchi, G., Yukihara, E., Cucinotta, F., Semones, E., Zapp, N., Miller, J. and Dettmann, J. Astronaut's Organ Doses Inferred from Measurements in a Human Phantom Outside the International Space Station. Radiat. Res. 171, 225–235 (2009). Space radiation hazards are recognized as a key concern for human space flight. For long-term interplanetary missions, they constitute a potentially limiting factor since current protection limits for low-Earth orbit missions may be approached or even exceeded. In such a situation, an accurate risk assessment requires knowledge of equivalent doses in critical radiosensi...