A Lightweight EVA Emergency System

With an increased rate and length of extravehicular activities (EVAs), a low, but statistically significant possibility exists for system and component failures. In that potential event, it is critical to provide oxygen support, carbon dioxide and moisture removal and thermal control to sustain life. The existing EVA emergency system in the Portable Life Support Unit (PLSS) is reliable, and works well, however, it is heavy because of the high oxygen consumption inherent in its open-loop mode of operation. TDA Research, Inc. (TDA) is developing a low-venting emergency system that provides 30-minute life-support in the case of system or component failures in the Portable Life Support System (PLSS). The approach is to minimize the quantity of the gas vented from the suit and thereby to reduce the weight of the stored oxygen. The operation of the system however, requires an effective sorbent that would remove carbon dioxide from the suit. TDA has developed such a sorbent. This paper describes the system components in a sorbent based EVA emergency system and the development of a prototype system.