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A summary of an ESA/ESTEC sponsored technology research programme is given aiming at the development of a CO2 partial pressure sensor suitable for monitoring the PP CO2 inside the oxygen ventilation loop of the EVA life support module. At first, a trade-off of candidate sensor concepts is presented. As result, the infrared optical sensor concept has been selected. In the frame of a discussion on basic facts of IR absorption the rationale for the selected configuration of the IR sensor is given. A breadboard model of the PP CO2 sensor together with a test set-up has been established. The sensor was subjected to a test programme consisting of two separate test periods. The main results are given. Finally, the findings are discussed in the light of the development of future flight hardware.

A European Extra-Vehicular Activity (EVA) System is being developed by the European Space Agency (ESA) as part of its Hermes Programme, with the primary objective of providing a manned intervention capability for external servicing of the Columbus Free Flying Laboratory. The development phase started in 1988. A major design driver for the EVA system is the required level of failure tolerance, to ensure the achievement of sortie objectives and crew safety. The failure tolerance requirements placed on the EVA system may be summarised as follows: no single failure should result in sortie abort, and a safe return to the Hermes “safe-haven” should be possible following a second failure. This paper presents possible design solutions to this requirement, in particular for life support and associated functions. The failure tolerance characteristics of existing American and Russian EVA systems are also examined for comparison.

During the last years extensive work has been done to design and develop the Closed-Loop Air Revitalization System ARES. The potential of ARES e.g. as part of the ISS ECLSS is to significantly reduce the water upload demand and to increase the safety of the crew by reducing dependence on re-supply flights. The design is adapted to the interfaces of the new base lined Russian MLM module as possible location for a future installation of ARES. Due to the lack of orbital support equipment and interfaces to a waste water bus, to a feed water supply line and due to the availability of only one single vent line it was necessary to make the ARES process water loop as independent as possible from the host vehicle. Another optimization effort was to match the CO2 desorption profile with the available hydrogen flow to achieve a sufficient water recovery performance, while meeting all related safety requirements, minimizing complexity and improving reliability.

ESA has been developing regenerative physicochemical air revitalisation technology for more than 20 years. The effort is now maturing into a flight demonstration experiment which is planned to be located in the Columbus module on ISS. The experiment shall be sized for a crew of three. It will comprise a CO2 concentration assembly, a Sabatier reactor and an electrolyser. The paper describes the adaptation of ARES to the available Columbus interfaces as well as ARES development status, performances, benefits to the ISS and operational agreements with ISS partners.

EADS SPACE Transportation GmbH designed, built and tested a condensate buffer to be located between a Condensing Heat Exchanger (CHX) and a Condensate Water Separator Assembly (CWSA), as part of the ECLSS of the European Columbus Module. Under zero-g conditions, the separation of water from an air-water mixture is always difficult, especially if a passive device is to be used such as the low power consuming Columbus CWSA. The additional buffer volume reduces condensate water peaks reaching the CWSA to a level that excludes an overloading of the CWSA and a release of free water droplets into the air return to the cabin. In the CHX/CWSA system this may only be necessary under worst case operational conditions and with a failure of the qualified hydrophilic coating of the CHX. The buffer design principle was confirmed via prior analyses and on-ground testing. The performance of such a condensate buffer under micro-g conditions was verified during parabolic flights.

During the last years extensive work has been done to design and develop the Closed Loop Air Revitalization System ARES. The potential of ARES for future space exploration missions is to significantly reduce the water upload demand, increase the safety of the crew by reducing dependency on re-supply flights and, due to the launch mass restraints, make future exploration missions to other planets possible. The ARES demonstrator includes the functions of CO2 concentration, CO2 reduction and oxygen generation. Whereas in previous phases ARES was designed to operate in NODE3 of the ISS, this has been changed to an intended ARES operation in the Russian Multifunctional Laboratory Module MLM. This year’s activities concentrated on process optimization of the Carbon Dioxide Removal Assembly (CCA) interaction with the Sabatier Reactor (CRA), extreme conditions testing, life time tests with the Sabatier Reactor and the oxygen generation stack and system testing.

Under an ESA Contract EADS SPACE Transportation GmbH has designed and built an advanced Stainless Steel Condensing Heat Exchanger (CHX) Spare as part of the Environmental Control and Life Support Subsystem (ECLSS) of the European Columbus Module that shall be docked to the ISS in early 2007. Lessons learnt from both, ground and space applications of condensing heat exchangers were to be considered, for risk mitigation, in a CHX alternative design. The slurper section is equipped with a sophisticated capillary suction feature that supports an adequate condensate removal and transport through the slurper holes to the water separator assembly even at low airflow condition. The air fin surface is covered with a hydrophilic coating that did pass qualification for 10 years' exposure to the various contaminants specified respectively determined in the ISS atmosphere so far. The biocidal additive of such coating is qualified for fungus growth prevention, accordingly.

During the last years extensive work has been done to design and develop the Closed Loop Air Revitalization System ARES. The potential of ARES for future space exploration missions is to significantly reduce the water upload demand, increase the safety of the crew by reducing dependency on re-supply flights and due to the launch mass restraints - make future exploration missions to other planets possible. Past years’ activities concentrated on the development of a full-scale demonstrator which was in form, fit, and function comparable to an ‘engineering model’ (EM). Most equipment was off-the-shelf and has been mechanically upgraded to EM standard. The demonstrator includes the functions of CO2 concentration, CO2 reduction and oxygen generation. All components fit into one ISPR. The design minimizes the number of external interfaces in order to achieve a high degree of independence and flexibility. Design baseline for the development was the accommodation in NODE 3 of the ISS.

A final test activity was carried out to complete the verification of the Environmental Control System (ECS) performances by experimentally reproducing the thermal hydraulic behaviour of the Environmental Control & Life Support Subsystem (ECLSS) section integrated in the overall Module, expected on analytical basis. A previous test campaign (called Columbus ECS PFM Test) carried out in EADS-Bremen in spring 2003 and described in paper number 2004-01-2425 showed some contradictory data concerning the air loop behaviour. These incoherent test results were related to the environmental and geometrical cabin loop conditions during the on-ground 1g test and to improper position of the sensor measuring the cabin temperature. For this reason a partial repetition of the test has been performed. In particular, this experimental campaign was focused on the verification of the cabin air temperature control, as a consequence of the Temperature Control Valve (TCV) movement.

At the 2002 ICES, FAVORITE, the orbital flight experiment for a fixed alkaline electrolyte (FAE) electrolyser stack was presented. The planning at that time was to fly the experiment in September 2003 on board the Space-Hab mission STS-118 with the space shuttle COLUMBIA flight ISS-13A.1. Due to the tragic accident of COLUMBIA on Feb. 1st, 2003, these plans became obsolete and alternative launch opportunities were looked for. They were finally found with the unmanned Russian FOTON-M2, which is built by TsSKB-PROGRESS in Samara, Russia and scheduled for launch from the Baikonur cosmodrome in April 2005. Because of the switch from a manned to an unmanned mission and other operational constraints, FAVORITE had to be redesigned in several parts. This paper summarizes the objectives of the flight experiment and describes the required design changes. It also presents an overview of the actual development status as well as of the work ahead.