Quality of ATV Potable Water for ISS Crew Consumption

Abstract

Potable water is undoubtedly one of the most critical resources for the International Space Station (ISS) crews. The amount and quality of this resource, mainly provided to the ISS by the Space Shuttle and Progress, and in the near future by logistic vehicles Automated Transport Vehicle (ATV) and HTV, must be compatible with the crew consumption needs and health-related requirements. For this purpose, potable water must satisfy very stringent quality requirements from chemical and bacteriological point of view. The definition of such requirements, resulting from medical studies, lessons learned, technical constraints, is reached in agreement among ISS International Partners. Two different quality standards are defined, one for the ISS Russian Segment, the other for the US Segment and other International Partners. The ATV, a program under European Space Agency (ESA) contract and EADS Space Transportation (EST) prime contractor-ship, is the only logistic vehicle requested to transport and deliver potable water to ISS according to both quality standards. Significant efforts have been spent in Alenia Spazio, responsible for the ATV Integrated Cargo Carrier, to define all the activities necessary to accomplish this task. The main aspects under consideration have been: selection of materials in contact with water, identification of suitable potable water sources, water preparation and disinfection, and pre-conditioning of equipment. This paper focuses on preparation and quality of potable water as obtained in dedicated ground facilities. The quality and stability of source water are an essential pre-requisite to attain the required standards. Disinfection techniques using colloidal silver and iodine are discussed, and their implementation in the ATV Water Preparation Facility at Societa Metropolitana Acque Torino (SMAT) premises is presented. The results of chemical and micro-biological analyses performed on potable water batches treated with the defined techniques show that the requirements are fully satisfied.