Preliminary Experimental Studies of Water-Energy-Cycle Space Propulsion System

Abstract

The Water-Energy-Cycle Space Propulsion System (WECSPS) is a system to support long-term and large-scale space activity. On a test stand which can change attitude, the demonstrator was assembled, the attitude was changed through ±1G, and the performance of the demonstrator was measured. As a result of experimenting in ±1G, when it operated normally in every case, as did separation of gas and liquid at the level of each subsystem, it turned out satisfactorily and many useful things were learned. It was concluded that it would probably operate satisfactorily in micro-gravity. The Proton Exchange Membrane (PEM) electrolyzer and the fuel cell which were used for the experiment comprised the regenerative fuel cell for the experiment, and used a single cell for this research at normal temperature. The phenomenon of ignition delay was improved by improving the injector structure, and adjusting the injection timing in the catalyst ignition experiment of hydrogen/oxygen thruster. It turns out that water adheres to the catalyst layer surface after the end of combustion. The Water-Energy-Cycle Space Propulsion System (WECSPS) combines a Water-Energy-Cycle System and a Propulsion System, and provides the three functions of life support system, energy storage and power generation, and propulsion for attitude and orbit control. In principle it can be used for manned space systems in near-Earth space and near the Moon. The concept is shown in Figure 1. The Water-Energy-Cycle Space Propulsion System (WECSPS) stores hydrogen and oxygen produced by electrolyzing water with electric power generated by photovoltaic panels. At times of shadowing etc, the hydrogen and oxygen which were stored are used for power generation by fuel cells, or are used as propellant. The quantity of hydrogen/oxygen to be stored can be decided freely. For this reason, it could be used for power generation for the 15-day night at a lunar base, not only for orbital spacecraft. In addition, it is highly efficient by using hydrogen/oxygen as propellants, and non-toxic to humans. In this case, it is necessary to carry separately the water to be consumed as propellant. When used as a propulsion system, the WECSPS turns into propulsion supply system. Such a multifunctional space system could become lightweight through combining functions. Such a space system was considered for space stations in the US in the * This study is carried out as a part of Ground-based Research for Space Utilization promoted by Japan Space Forum.