![]() ![]() At these two ends the fluxes are negligible, and at the low end the ions are most likely stopped by the habitat shield. The spectra of all ions peaks at about 1-2 GeV/nucleon, and extend from low energies (a few MeV) well beyond the TeV region. The heavier ions, however, are more effective in damaging living tissues, so their contribution to the risk is comparable to the one caused by proton flux. About 85% of these are protons, 14% helium ions, and 1% heavier ions. The former is composed mostly by ions of all elements, from hydrogen to iron (the fluxes drop significantly for the charge Z>26). Space radiation ( Durante and Cucinotta, 2011) is mostly composed by Galactic Cosmic Rays (GCR) and Solar Particle Events (SPE). The validation of results obtained until now with space-relevant radiation is the sole way to finely forecast the plant behavior and to define the true cultivation requirements to obtain “well-functioning” plants efficiently providing the regeneration of resources and food production in BLSS for Space exploration. In this paper, when not specified, the reported study cases are referred to plants’ responses to photon-type radiation, but we underline the need for the scientific community to converge towards common standardization schemes in future experiments to test the effects of radiation. Moreover, even when experimental irradiation has been performed with charged particles, there is still the issue of poor space fidelity of the ‘radiation analog’ accelerators. Indeed, most available information derives from ground-based experiments in which plants or plant parts have been exposed to photon-type radiation and not to charged particles (i.e., protons and heavy ions constituting the most of space radiation). In this paper, we focus our attention on the main issues related to the radiation spatial and temporal variability as well as on the difficulty in identifying a standard behavior of plants in response to ionizing radiation due to the multiplicity of studies conducted with scopes which were not space-oriented. In BLSS, the problem of space radiation which may affect both the organisms and the electronic components of spacecrafts cannot be disregarded. In such systems, the biotic component (e.g., consumers, producers and decomposers) is integrated with physical/chemical processes to achieve a self-sustaining system allowing the regeneration of resources, fundamental to solve the issues of resupply from Earth and waste management ( De Pascale et al., 2021). These effects can be direct (on the astronauts themselves) or indirect, acting on items that are indispensable for the crew life, such as Bioregenerative Life Support Systems (BLSS). Radiation effects on the crew during space voyages must be reduced under a pre-agreed limit to allow for human deep space exploration. Indeed, the latter derives instead from experiments conducted with different radiation types and doses and often with not space-oriented scopes. We finally indicate some perspective, suggesting the direction future research should follow to standardize methods and protocols for irradiation experiments moving towards studies to validate with space-relevant radiation the current knowledge. In particular, we summarize some basic statements on plant radio-resistance deriving from recent literature and concentrate on endpoints critical for the development of Space agriculture. oxygen production, carbon dioxide removal, water and wastes recycling) and producers of fresh food. In fact, plants in BLSS act as regenerators of resources (i.e. In this paper, we first consider the radiation issue for space exploration from a physics point of view by giving an overview of the topics related to the spatial and temporal variability of space radiation, as well as on measurement and simulation of irradiation, then we focus on biological issues converging the attention on plants as one of the fundamental components of Bioregenerative Life Support Systems (BLSS). Therefore, it is fundamental to achieve a deep knowledge on the radiation spatial and temporal variability in the different mission scenarios as well as on the responses of different organisms to space-relevant radiation. 3Physics Department, University of Rome “Tor Vergata”, Rome, Italyįor deep space exploration, radiation effects on astronauts, and on items fundamental for life support systems, must be kept under a pre-agreed threshold to avoid detrimental outcomes.2Laboratory of Ecology, Department of Biology, University of Naples Federico II, Naples, Italy. ![]() 1Laboratory of Plant and Wood Anatomy, Department of Agricultural Sciences, University of Naples Federico II, Naples, Italy.Veronica De Micco 1*, Carmen Arena 2, Luca Di Fino 3 and Livio Narici 3
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