Farming on Extraterrestrial soil.

Concerning the life maintenance of a crew on extraterrestrial planetary bases, the technologies currently used in space ships are not self-sustaining, resulting thus inappropriate. In this context, the soil capacity to degrade almost everything by mineralization, thus recycling the principal elements, to purify water and to store carbon dioxide by humification processes shall necessarily be used to permit the life maintenance of human colonies on extraterrestrial planets. We have thus to consider space farming as the smart soil-plant management for human extraterrestrial base sustainability in order to create a green system, able to recycle organic waste, purify water and air, producing oxygen and transforming carbon dioxide in organic compounds by photosynthetizing organisms, ingenerating the food chain. In the present contribution are evidenced the main problematic related to cultivation in Moon and Mars soils in relation to their pedo-chemical and environmental characteristics. The moon soils have homogeneous chemico-physical characteristics, resulting from mechanical disintegration of basaltic and anorthositic basic rock, caused by continuous meteoric impact over billions of years in which the soil top layer particles are ground to finer and finer size over time. The meteorites impact on Moon soils have also induced an unusual chemical reactivity in the dust particles, inducing the formation inside them glass bubbles inside filled with a highly porous network of infinitesimal nanophase-sized Fe00, that electrostatically charged the dust particles thus developing a type of soil which is unknown on Earth. Concerning Mars soils evolution it has to be consider that almost initially ( 3-4 billion years ago) the environmental conditions were similar to those on earth, whereas later the environmental conditions resulted similar to those of Moon. In fact, the presence of liquid water in the past have induced the presence of particular minerals rocks such as jarosite and mugearite, and also the formation of clays, that means the colloidal properties. Moreover the different origin of Earth and Mars respect to Moon are reflected in the extreme variability in chemico-physical characteristics of Earth and Mars soils with also marked pH differences, ranging from acidic, neutral and alkaline conditions. The extremely fine soil top layer of both Moon and Mars planets induce an extremely high surface areas and micro-porosity, causing a low solutes and gasses circulation, and also a low solute retention capacity respect to Earth’soils. The water origin, characteristics and amount among Moon and Mars are relevant. Mars is characterized by an higher water amount, where it has present as ice and also probably in liquid form in the subsurface soils, and is characterized by high saline content. Whereas on Moon the water is mainly present in the rock and resulted originated by solar wind. Both planet soils resulted characterized by the practically absence of nitrogen, the possible contamination by heavy metals, and for Mars the presence of highly hygroscopic salts and superoxides, due to the incidence of high energy radiation to exposed mineral surface.. On Mars it will be possible to find carbon dioxide and a trace amount of nitrogen in atmosphere; potassium and phosphor in minerals. Finally both Mars and Moon soils, due to their extreme dusty could result dangerous for human health, with health greater risks for lunar dust due to its higher chemical reactivity and larger surface areas. Agronomically these soil characteristics represent a challenge that request special approaches that will be mainly related to develop an adeguate soil structure combined with a proper irrigation system and soil pH control. In fact , difficult gas and solutes circulation lead to suffocation of aerobic microorganisms and roots, emissions of toxic gases. The extreme soils pH values could drastically reduce the nutrient availability and influence the soil microbial community. Moreover the water salt content could request special plant’s cultivation system and/or water pre-treatment. Finally the possible presence of superoxides and heavy metals should request suitable soil management practices.