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A zirconia electroysis cell is an all-solid state (mainly ceramic) device consisting of two electrodes separated by a dense zirconia electrolyte. The cell electrochemically reduces carbon dioxide to oxygen and carbon monoxide at elevated temperatures (800 to 1000°C). The zirconia electrolysis cell provides a simple, lightweight, low-volume system for Mars In-Situ Resource Utilization (ISRU) applications. This paper describes the fabrication process and discusses the electrochemical performance and other properties of zirconia electrolysis cells made by the tape calendering method. Electrolytes produced by this method are very thin (micrometer-thick); the thin electrolyte reduces ohmic losses in the cell, permitting efficient operation at temperatures of 800°C or below.

A molecular-sieve-based portable life support system (PLSS) for microgravity extravehicular activity (EVA) has been designed to minimize weight, volume, and expenditures of consumables for missions with numerous EVA's. The PLSS incorporates a regenerable two-bed molecular sieve system for CO2 and humidity removal, and a regenerable nonventing thermal sink for temperature control. The molecular-sieve-based PLSS design is modular. This approach simplifies initial manufacturing tasks, facilitates subsequent maintenance tasks, and provides the potential to tailor the PLSS to the specific environmental parameters (metabolic load, radiative environment, duration) of a given EVA excursion. This paper presents the molecular-sieve/regenerative nonventing thermal sink PLSS design and discusses the analyses and trade studies which support the design. The modular design and its benefits are discussed, and the reduced launch weight requirements of the regenerable system are quantified.

One of the primary safety concerns for Space Station Freedom pressurized modules is fire. Some Freedom modules are unattended for long periods of time. In other cases, enclosed, pressurized volumes are not open to crew monitoring. As a result, a fire detection system is required to continuously monitor all modules for combustion. This paper briefly reviews the overall design for the Freedom fire detection system, and the design of the two basic types of detectors: smoke and flame. The smoke detectors monitor particulates in small open areas, stand-offs, end-cones, and racks. The flame detectors survey open areas for radiation at wavelengths and intensities characteristic of combustion. Responses from detectors are evaluated by Freedom's data management system to determine the presence of combustion and to recommend appropriate action.

A flexible fire detection system is required in order to monitor Space Station Freedom pressurized volumes, including spaces which may be inaccessible to the crew, or may be unattended for long periods of time. The system uses flame detectors to survey open areas for radiation at wavelengths and intensities characteristic of combustion, and uses smoke detectors to monitor particulates in open areas and in air circulation ducts. This paper briefly reviews the design of the system and the detectors and presents results of development testing of the smoke detectors. The duct-type smoke detector has met all Space Station Freedom performance requirements.