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In preparation for the contract award of the Crew Exploration Vehicle (CEV), the National Aeronautics and Space Administration (NASA) produced two design reference missions for the vehicle. The design references used teams of engineers across the agency to come up with two configurations. This process helped NASA understand the conflicts and limitations in the CEV design, and investigate options to solve them.

As part of preparing for the Crew Exploration Vehicle (CEV), the National Aeronautics and Space Administration (NASA) worked on developing the requirements to manage the fire risk. The new CEV poses unique challenges to current fire protection systems. The size and configuration of the vehicle resembles the Apollo capsule instead of the current Space Shuttle or the International Space Station. The smaller free air volume and fully cold plated avionic bays of the CEV requires a different approach in fire protection than the ones currently utilized. The fire protection approach discussed in this paper incorporates historical lessons learned and fire detection and suppression system design philosophy spanning from Apollo to the International Space Station.

NASA's Constellation Program, which includes the mission objectives of establishing a permanently-manned lunar Outpost, and the exploration of Mars, poses new and unique challenges for human life support systems that will require solutions beyond the Shuttle and International Space Station state of the art systems. In particular, the requirement to support crews for extended durations at the lunar outpost with limited resource resupply capability will require closed-loop regenerative life support systems with minimal expendables. Planetary environmental conditions such as lunar dust and extreme temperatures, as well as the capability to support frequent and extended-duration Extra-vehicular Activity's (EVA's) will be particularly challenging.

The Japanese Experimental Module (JEM) Pressurized Module (PM) is a facility where astronauts conduct experiments or control the total JEM facility. Inside the PM, the air composition, temperature and humidity are controlled so as to be comfortable for astronauts' activity all the time. The verification of the on-orbit performance of the functions constituting a manned space system is one of the critical points. Computational Fluid Dynamics (CFD) simulation technology is utilized to characterize and investigate the airflow in the JEM for various operating conditions. The development of a successful CFD model for International Space Station (ISS) operation is useful because there are always off-nominal and other contingency operations, which might occur and could be analyzed using an existing CFD model. This paper also presents the cabin ventilation test data obtained from the JEM flight module.

The International Space Station (ISS) Environmental Control and Life Support (ECLS) system includes regenerative and non-regenerative technologies that provide the basic life support functions to support the crew, while maintaining a safe and habitable shirtsleeve environment. This paper provides a summary of the U.S. ECLS system activities over the past year, covering the period of time between April 2002 and March 2003. The ISS continued permanent crew operations, with the start of Phase 3 of the ISS Assembly Sequence. Work continued on the Phase 3 pressurized elements with Node 3 just completing its final design review so that it can proceed towards manufacturing and the continued manufacturing of the regenerative ECLS equipment that will be integrated into Node 3.

The International Space Station (ISS) Environmental Control and Life Support (ECLS) system includes regenerative and non-regenerative technologies that provide the basic life support functions to support the crew, while maintaining a safe and habitable shirtsleeve environment. This paper provides a summary of the ECLS System On-Orbit Station Development Test Objective (SDTO) status from the start of assembly until the end of February 2003.

The International Space Station (ISS) underwent a dramatic buildup in life support equipment since the delivery and activation of the U.S. Laboratory module in February 2001, followed by the Joint Airlock in July 2001. Since Laboratory activation, several Environmental Control and Life Support (ECLS) equipment failures have occurred. This paper addresses these failures, occurring through February 2002, and, where known, the root causes, with particular emphasis on probable micro-gravity causes are highlighted. Impact to overall ISS operations and proposed or accomplished fixes also are discussed.

The Extravehicular Mobility Units (EMUs) onboard the International Space Station (ISS) experienced a failure due to cooling water contamination from biomass and corrosion byproducts forming solids around the EMU pump rotor. The coolant had no biocide and a low pH which induced biofilm growth and corrosion precipitates, respectively. NASA JSC was tasked with building hardware to clean the ionic, organic, and particulate load from the EMU coolant loop before and after Extravehicular Activity (EVAs). Based on a return sample of the EMU coolant loop, the chemical load was well understood, but there was not sufficient volume of the returned sample to analyze particulates. Through work with EMU specialists, chemists, (EVA) Mission Operations Directorate (MOD) representation, safety and mission assurance, astronaut crew, and team engineers, requirements were developed for the EMU Water Processing hardware (sometimes referred to as the Airlock Coolant Loop Recovery [A/L CLR] system).

Following the Colombia accident, the Extravehicular Mobility Units (EMU) onboard ISS were unused for several months. Upon startup, the units experienced a failure in the coolant system. This failure resulted in the loss of Extravehicular Activity (EVA) capability from the US segment of ISS. With limited on-orbit evidence, a team of chemists, engineers, metallurgists, and microbiologists were able to identify the cause of the failure and develop recovery hardware and procedures. As a result of this work, the ISS crew regained the capability to perform EVAs from the US segment of the ISS Figure 1.

One of the most critical functions of ECLSS is to maintain the atmospheric oxygen concentration within habitable limits. On the ISS, this function is provided by the Major Constituent Analyzer (MCA). During ISS (International Space Station) crew increments 7 thru 9, the MCA was at risk of imminent failure as evident by sustained high ion-pump current levels. In the absence of continuous constituent measurement by the MCA, manual methods of estimating partial pressure of oxygen (ppO2) and concentration levels need to be developed and validated to: (1) ensure environmental control and life support, (2) prohibit ISS system and hardware damage, and (3) enable planned ISS activities that effect constituent balance.

An ISS internal Quick Disconnect (QD) coupling failure during proto-flight vibration testing of ISS regenerative Environmental Control and Life Support (ECLS) hardware raised issues concerning the performance of the male QD housing seal design. The existing QD acceptance screening process does not address performance of redundant housing seals and therefore failure tolerance cannot be assured for hardware currently in service. The possibility of performance issues has large implications when considering that currently there are 399 similar units on orbit and approximately 1100 units on the ground integrated into flight hardware. Testing, analysis, and development of a plan to address this issue both for existing hardware and future hardware has been completed to assure system safety is not adversely affected.

The Carbon Dioxide Removal Assembly (CDRA) is an essential part of the International Space Station (ISS) Environmental Control and Life Support (ECLS) system. The CDRA provides carbon dioxide (CO2) removal from the ISS on-orbit modules. Currently, the CDRA is the secondary removal system on the ISS, with the primary system being the Russian Vozdukh. The CDRA encountered some operational problems since being launched to orbit on Flight 5A in February 2001. While on-orbit, several hardware modifications and maintenance activities have been necessary to restore the CDRA to nominal capability. This paper describes the troubleshooting activities and briefly explains the failures, the operational workarounds, and the on-orbit hardware repairs performed to return the CDRA to operational status.

The baseline environmental control and life support (ECLS) systems currently deployed on board the International Space Station (ISS) and that planned to be launched in Node 3 are based upon technologies selected in the early 1990's. While they are generally meeting or exceeding requirements for supporting the ISS crew, lessons learned from years of on orbit and ground testing, together with new advances in technology state of the art, and the unique requirements for future manned missions prompt consideration of the next logical step to enhance these systems to increase performance, robustness, and reliability, and reduce on-orbit and logistical resource requirements. This paper discusses the current state of the art in ISS ECLS system technologies, and identifies possible areas for enhancement and improvement.

The Orion Crew Exploration Vehicle (CEV) requires a smoke detector for the detection of particulate smoke products as part of the Fire Detection and Suppression (FDS) system. The smoke detector described in this paper is an adaptation of a mature commercial aircraft design for manned spaceflight. Changes made to the original design include upgrading the materials and electronics to space-qualified components, and modifying the mechanical design to withstand launch and landing loads. The results of laboratory characterization of the response of the new design to test particles are presented.

High pressure oxygen onboard the ISS provides support for Extra Vehicular Activities (EVA) and contingency metabolic support for the crew. This high pressure O2 is brought to the ISS by the Space Shuttle and is transferred using the Oxygen Recharge Compressor Assembly (ORCA). There are several drivers that must be considered in managing the available high pressure O2 on the ISS. The amount of O2 the Shuttle can fly up is driven by manifest mass limitations, launch slips, and on orbit Shuttle power requirements. The amount of O2 that is used from the ISS high pressure gas tanks (HPGT) is driven by the number of Shuttle docked and undocked EVAs, the type of EVA prebreath protocol that is used and contingency use of O2 for metabolic support. Also, the use of the ORCA must be managed to optimize its life on orbit and assure that it will be available to transfer the planned amount of O2 from the Shuttle.

This paper describes the requirements for and design implementation of an air monitor for the Orion Crew Exploration Vehicle (CEV). The air monitor is specified to monitor oxygen, nitrogen, water vapor, and carbon dioxide, and participates with the Environmental Control Life Support System (ECLSS) pressure control system and Atmosphere Revitalization System (ARS) to help maintain a breathable and safe environment. The sensing requirements are similar to those delivered by the International Space Station (ISS) air monitor, the Major Constituent Analyzer or MCA (1, 2 and 3), and the predecessors to that instrument, the Skylab Mass Spectrometer (4, 5), although with a shift in emphasis from extended operations to minimized weight. The Orion emphasis on weight and power, and relatively simpler requirements on operating life, allow optimization of the instrument toward the mass of a sensor assembly.

The Orion Crew and Service Modules are often compared to the Apollo Command and Service Modules due to their similarity in basic mission objective: both were dedicated to getting a crew to lunar orbit and safely returning them to Earth. Both spacecraft rely on the environmental control, life support and active thermal control systems (ECLS/ATCS) for the basic functions of providing and maintaining a breathable atmosphere, supplying adequate amount of potable water and maintaining the crew and avionics equipment within certified thermal limits. This assessment will evaluate the driving requirements for both programs and highlight similarities and differences. Further, a short comparison of the two system architectures will be examined including a side by side assessment of some selected system's hardware mass.