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When humans visited the moon, the lunar rover provided an enabling resource that dramatically multiplied the scope of their exploration activities and science yield. Due to longer expected mission durations and Mars’ larger size and higher gravity, rovers will be even more crucial to effective human exploration. Unlike the Apollo program in which rovers were added part way through the program, rovers for Mars can be fully considered and integrated into the development of EVA systems at the outset. Research and mission studies of Mars exploration systems at HSSSI and elsewhere in recent years reflect this thinking. However, specifics have varied widely from small, EVA-assist rovers that are not ridden to large, pressurized rovers intended to support extended traverses over hundreds of kilometers.

International Space Station includes a Joint Airlock in the U. S. on-orbit segment to support U. S. and Russian extravehicular activity (EVA). In this plan, the U. S. Extravehicular Mobility Unit (EMU) and the Russian Orlan-M spacesuit system share a common vehicle water coolant loop. Since the two spacesuit systems use different biocide additives and contain different non-metallic materials in their respective cooling water loops, steps are being taken to insure that no deleterious effects occur due to the mixing of Orlan-M and EMU coolant water. This paper describes the activities of the Russian and U.S. International Space Station and EVA teams to understand the implications of using both countries' EVA systems in such a deeply interconnected manner. The paper discusses a current U.S. test program and Russian analyses, and presents results to-date in an ongoing issue.

In 1993 the United States and Russia signed an historic agreement committing both countries to a broad range of cooperative activities in space. This agreement included the “development of a common space suit.” This paper describes the major elements of a Common Space suit System (CSS) approach, presents the current status of flight planning towards implementing the agreement, and discusses some future challenges. Planning the CSS program revealed different theoretical “levels of commonality,” ranging from minimum interoperability to a concept of a single, common design embodying common manufacturing and full interchangeability. Reviewing these reveals some of the practical limitations to commonality that relate to both evolution (of existing U.S. and Russian space suits) and revolution (a brand new space suit).

A fresh look at the use of astronaut time to conduct and support Extravehicular Activity (EVA) can help guide the evolution of next generation EVA systems. Studies have shown that less than 20% of the flight crew time for EVA (prior/during/post) is currently spent directly on productive tasks. In the future, longer missions, larger and more complex orbiting platforms and on-orbit maintenance of EVA equipment will drive this percentage even lower. Study of where the remaining 80% of the flight crew time presently goes indicates where improvements could be aggressively pursued for next generation systems. With the high cost per manhour on orbit, and estimated needs for 200 or more crew hours of EVA annually for space station, these improvements are clearly worthwhile. Current use of crew time before, during and after EVA were analyzed, and major uses of time identified.

The European Agency (ESA) and the Russian Space Agency (RKA) are jointly developing a new space suit system for improved extravehicular activity (EVA) capabilities in support of the MIR2 Space Station Programme, the EVA Suit 2000. Recent national policy agreements between the U.S. and Russia on planned cooperations in manned space also propose the development of a common space suit system for potential use with the International Space Station. It is thus timely to report the current status of ongoing work on international EVA interoperability being conducted by the Committee on EVA Protocols and Operations of the International Academy of Astronautics initiated in 1991. This paper summarises the current EVA interoperability issues to be resolved and presents quantified vehicle interface requirements for the current U.S. Shuttle EMU and Russian MIR Orlan DMA and the new European/Russian EVA Suit 2000 extravehicular systems.

America and Russia have independently implemented designs of individual life support systems to provide extravehicular activity (EVA) capability in support of the Space Shuttle and Orbital Station Mir programs. With the end of the “cold war,” and establishment of new cooperative relationships between America and Russia, joint space ventures are being planned. Mixed American and Russian crews are currently training for upcoming Space Shuttle and Orbital Station Mir missions with a Shuttle-to-Mir rendezvous flight scheduled for 1995. While not currently planned, a joint American and Russian effort to develop and demonstrate Space Shuttle and Mir compatibility to conduct an extravehicular crew rescue from either country's spacecraft would appear to be a desirable future objective.

The current Shuttle EMU (Extravehicular Mobility Unit) uses expendable water to provide cooling to the EMU. For Space Station Freedom (SSF), one potential source of this water is the SSF potable water processor (PWP). Concerns exist about utilizing the SSF water for the EMU sublimator because the SSF PWP effluent may contain low soap concentrations. Traces of soap-like compounds (surfactants) have been shown to affect EMU sublimator performance at low concentrations. Results of testing indicate that a subscale sublimator functions equally well with both SSF PWP effluent and Shuttle quality deionized water. Furthermore, only minor performance anomalies are observed with water purposely spiked with maximum allowable concentrations of baseline shower soap. Not all surfactants are equally detrimental to sublimator performance. Testing with a full scale sublimator is the next step.

The Space Shuttle Program Extravehicular Mobility Unit (SSP EMU) will support initial phases of the Space Station Freedom program. These phases are station assembly and man-tended operation from Shuttle and the first stages of Station's permanently manned capability. Station support increases requirements for on-orbit duration, adds new requirements for accommodation aboard Freedom and adds new environments unique to Freedom. Building upon enhancements currently in the EMU program, the SSP EMU appears to be well capable of meeting these new requirements. Certification will be extended by analysis and test and supported by limited redesign in a few specific areas. This paper discusses the enhanced EMU, identifies the new requirements for Space Station Freedom support, the process for identifying and approving these requirements, and the expected delta certification and limited redesign programs.

The various configurations being considered for Space Station Freedom have resulted in a moving target for tomorrow's demand for EVA and the requirements that will be imposed on the Extravehicular Mobility Unit (EMU). The Shuttle EMU is baselined to perform the assembly and operational activities of station and is currently undergoing the necessary incremental re-certification. This paper presents the evolution of an EMU from two perspectives. First, evolution is discussed within the context of continuously improving the life support system and the space suit assembly from the Mercury Program to NASA's current flight EMU. This includes a status of the on-going enhancements and a discussion on the merits of additional improvements. The second perspective describes evolution for future programs involving significant differences in mission requirements and environments.

EMU hardware processing, the refurbishment and checkout subset of EMU ground turn-around activities between Shuttle flights, is significantly lower today than it was when EMUs began regular service aboard Shuttle. Despite a significant increase in safety checkout steps resulting from the Challenger accident, hands-on processing time has dropped from approximately 4,000 manhours per EMU then to approximately 1,050 manhours now. The following aspects of hardware maturity contribute to this reduction: EMU hardware problems have been identified and fixed. Flight hardware and ground test rigs were designed or modified to simplify testing, and test procedures were standardized and streamlined. Increased confidence in the hardware allows extension of inspection, service and test intervals. The hardware processing sequence has recently been simplified and implementation is expected to reduce EMU hardware processing time to approximately 600 manhours/EMU in the near future.