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Materials used for manned space flight are tightly controlled to ensure the safety of the crewmembers. Significant changes to the economic environment as well as impact from environmental restrictions have resulted in material obsolescence that requires recertification or revalidation, increasing cost and risk to the program. This paper will review the impact this issue has had on the Shuttle Extravehicular Mobility Unit (EMU) Space Suit Assembly (SSA) and will provide insight into challenges expected for the Constellation Space Suit System (CSSS) program. Factors that affect availability, the impacts of material obsolescence, identification processes and risk reduction and management are described.

The health of inflatable structures, including space suits and habitats, is dependent upon the integrity of the gas retention structural layer. Inflatable structures typically utilize a coated fabric gas retention layer, or bladder. Threats such as Micrometeoroid and Orbital Debris (MMOD) penetration and inadvertent impact with sharp objects can cause a breach of the gas retention layer. Leakage as a result of bladder breach will impact operations due to loss of consumables and time spent locating and repairing the defect. Crew safety can be at risk where high rate leakage could cause loss of mission or loss of life. ILC has recently researched self-healing technologies that prevent leakage by closing penetrations of the gas retention structure and that are viable and scalable for various future missions and applications ranging from the Constellation Space Suit System (CSSS) to deployable lunar habitats. Several candidates of passive self-healing systems were studied.

During STS-116 extravehicular activity (EVA), a crewmember received a cut in the Glove Thermal Micrometeoroid Garment (TMG) as a result of contact with an unknown, external sharp object that did not meet sharp edge requirements. Since that mission, several additional gloves have experienced similar damage. Although sharp edge requirements exist for equipment interfaces with the space suits, damage to equipment can produce sharp edge conditions. In addition, crewmembers may be required to handle equipment or items not intended for crew contact resulting in exposure. This hazardous condition will still be possible for Constellation missions and therefore will continue to be a concern for the Constellation Space Suits System (CSSS) program. An investigation has been conducted into the cut glove TMG including material property reviews, material cut resistance properties, Glove response to cuts and system impacts.

Effective thermal and micrometeoroid protection as afforded by the Thermal Micrometeoroid Garment (TMG) is critical in achieving safe and efficient missions. It is also critical that the TMG does not increase torque or decreased range of motion which can cause crewmember discomfort, fatigue, and reduced efficiency. For future exploration missions, removable and replaceable TMGs will allow the use of different pressure garment protective covers and TMG configurations for launch, re-entry, 0-G Extra Vehicular Activity (EVA), and lunar surface EVA. A study was conducted with the goal of developing high Technology Readiness Level (TRL), scalable, interface design concepts for TMG systems. The affects of TMG segmentation on mobility and donning were assessed. Closure mechanisms were investigated and tested to determine their operability after exposure to lunar dust. A TMG configuration with the optimum number of segments and location of interfaces was selected for the Mark III spacesuit.

A trade study was conducted with a goal to develop relatively high TRL design concepts for an Exploration Cooling Garment (ExCG) that can accommodate larger metabolic loads and maintain physiological limits of the crewmembers health and work efficiency during all phases of exploration missions without hindering mobility. Effective personal cooling through use of an ExCG is critical in achieving safe and efficient missions. Crew thermoregulation not only impacts comfort during suited operations but also directly affects human performance. Since the ExCG is intimately worn and interfaces with comfort items, it is also critical to overall crewmember physical comfort. Both thermal and physical comfort are essential for the long term, continuous wear expected of the ExCG.

NASA's Exploration Architecture announced in September 2005, calls for development and flight of a Crew Exploration Vehicle (CEV) no later than 2014 and return to the moon by 2020 with a goal to reach and explore Mars. Intra-Vehicular Activity (IVA) suit systems will need to comfortably protect the crew during launch entry and abort scenarios. Extra-Vehicular Activity (EVA) suit systems will need to provide the capability to perform contingency zero-gravity EVA from the CEV as well as surface EVA to explore the moon and Mars. Studies currently underway to begin definition of the IVA and EVA suits point to a two suit architecture, the first being a launch, re-entry, and contingency EVA system used from CEV, the second and later being a lunar surface mobility suit only. An important consideration, yet to be determined, is the level of commonality between the early CEV and late Lunar suits.

ILC Dover, LP designed and manufactured a rear entry upper torso prototype for the I-Suit advanced spacesuit. In September 2005 ILC Dover participated in the Desert Research and Technology Study (RATS) led by the Advanced Extravehicular Activity (EVA) team from National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC). Desert RATS is a two-week remote field test at Meteor Crater, Arizona. Team members are from NASA, several universities, and a number of industry partners. These groups come together to gain hands-on experience with advanced spacesuit systems and to develop realistic requirements for future Moon and Mars exploration. Desert RATS gave ILC Dover the opportunity to put the rear entry I-Suit through many rigorous tests. The lessons learned there will be valuable for determining basic requirements for future lunar and Mars missions. Desert RATS utilizes a ‘learn-by-doing’ approach for understanding what future requirements should be developed.

The success of astronauts in performing Extra-Vehicular Activity (EVA) is highly dependent on the performance of the spacesuit they are wearing. The Space Shuttle Extravehicular Mobility Unit (EMU) is a waist entry suit consisting of a hard upper torso (HUT) and soft fabric mobility joints. The EMU was designed specifically for zero gravity operations. With a new emphasis on planetary exploration, a new EVA spacesuit design is required. One of the key features of any space suit is the entry method. Historical examples of different entry types include waist entry, rear entry, bi-planar entry, and soft zipper type entry. Suit entry type plays a critical role in defining the overall suit architecture. Some of the critical suit features affected by entry type are suit don/doff capability, suit sizing, suit mass, suit volume, and suit comfort. In general, rear entry designs provide better don/doff capabilities.