The damage by radiation that can be expected during the storage of hydrogen-bonded propellants in outer space is analized in terms of the available data on radiation levels. On this basis, the alternatives of storing the propellants as liquids or as solids, at low temperature, are discussed, and account is taken of recent results on their thermal behaviour obtained at this Laboratory. Vitreous states of aggregation that could crystallize spontaneously after long periods of irradiation are shown to present some hazards that can be prevented. General considerations of radiation-damage detection in outer space are also made. Paramagnetic resonance is found to be of limited use although it could be used for studying the damage produced by intense solar flares. Solid-state devices are finally recommended.