The paper presents the basic operational requirements for a gas actuating medium feed-and-storage system of a propulsion installation of an automatic spacecraft with a nonpressurized body. A comparative analysis of the suggested measures for determining and monitoring the airtightness at a long-term spacecraft operation is provided. The lifecycle increase up to several years at the expend ofpower and fuel efficiency of a propulsion installation with gas rocket engines is evaluated based on experience of Yamal geostationary repeater spacecraft operation. There are some recommendations resulted from the analysis of those suggested measures for gas actuating medium feed and storage systems design and operation. The suggested measures are patented and currently are being used during spacecrafts operations.