2001-01-2168 Concept of Space Suit Enclosure for Planetary Exploration I. Abramov, N. Moiseyev and A. Stoklitsky RD&PE Zvezda Copyright © 2001 Society of Automotive Engineers, Inc. Abstract and bearings are possible. If we compare the PSS and orbital EVA space suit operational environments, additional factors, At present advanced projects of the early XXI century are which influence the PSS design are evident; e.g., gravity is a beginning to develop. These projects include lunar base considerable influence on the PSS enclosure including the development and manned missions to Mars. The space suit is lower torso assembly joints and bearings. The PSS weight one of the basic requirements for successful implementation of limitation makes us trade off between mass and mobility. Use future programs. The space suit enclosure enables mobility of of many bearings to provide maximum mobility at minimum crewmembers wearing pressurized space suits which will be effort may result in increasing the suit weight and dimensions required to complete these missions. and complicate suit operations. Compromise versions combining joints and smaller numbers of bearings, are Requirements on Planetary Space Suit (PSS) enclosure design, possible. especially for elements providing mobility of the lower torso assembly will be different from these on orbital space suit Hereafter, in analyzing the enclosure concept, the authors take enclosure design, intended for zero gravity conditions. into account the experience obtained in development of both the Lunar space suits (US A7LB and RF "Krechet") and The PSS enclosure provides cosmonaut/astronaut movement orbital space suits (US EMU and RF "Orlan") as well as test on planetary exploration surfaces, ascent/descent of the results for the latest development of space suits. Landing Module ladder, suited crewmember’s bending etc. Thus this PSS component will play a considerable role in Selecting the PSS enclosure design concept, the authors first successful fulfillment of extra-vehicular activity (EVA) tasks of all take into account the provision of such factors as: on planetary surfaces. - Minimal mass, - Range of motion, necessary for the planetary The paper comprises the following: exploration, n Analysis of the specific environmental conditions and - Anthropomorphic (natural) suited crewmember EVA characteristics on the Moon and Mars movements, - Ease of space suit donning/doffing. n Major PSS enclosure requirements n PSS enclosure design concepts analysis n The main purpose of the PSS is to provide for EVA on the PSS lower torso assembly concept for the Moon and Mars planetary surface. The issues of suit enclosure selection are considered here as applied to this purpose. Other possible considerations, usage for EVAs during interplanetary flight Introduction and PSS usage during landing/take-off as an IVA suit have not been addressed. In this connection, the paper pays most Russia and the USA have accumulated great experience in the attention to suit elements providing for walking mobility i.e. development and use of space suits for near-earth orbit EVA suit lower torso assembly (LTA). The influence of life support and for their lunar programs. This experience can be applied to system (LSS) characteristics, robotic devices, etc. on suit development of the next-generation space suit for the Moon enclosure design have not been discussed for brevity. and Mars. To a great extent, the success of these future projects will depend on selection of a PSS type, PSS enclosure concept, which provides for required cosmonaut mobility and Space suit operations on the Moon and Mars. other mission requirements. Table 1 presents some comparative data on environmental As is known, space suit enclosure mobility is provided by conditions, which must be taken into account in developing joints, which serve to bend enclosure elements, and ball and designing the PSS. bearings, which serve to rotate enclosure parts relative to each other. On the suit enclosure, various combinations of joints Table 1. Comparison of environmental conditions # Environmental Condition Near-earth orbit Moon Mars 1 Gravity 0 1.62 m/sec2 (0.17g) 3.91 m/sec2 (0.38g) 2 Pressure 0.0 bar 0.0 bar 6...11 bar 3 Surface temperature range −163...+112°C −163...+112°C −143...+17°C Among the tabulated data for the development of the PSS Performing intensive EVA, comfort provision for the suited enclosure design concept, the gravity environment has the crewmember are of great importance. In order to provide greatest impact. Another important factor is exposure to dust comfort for the crewmember wearing the suit, special soft on the Moon/Mars surfaces. It goes without saying, the suit inserts able to prevent pinching, numbing, chafing, cutting, outer garment – thermal micrometeoroid garment (TMG) will etc. must be included in the PSS enclosure design (thermal be required to protect the PSS enclosure from many dangers comfort requirements are not discussed in this paper). including dust penetration. Special design features are foreseen on the TMG/PSS enclosure to provide for: The Moon/Mars relief is uneven. The LTA design must allow the suited crewmember to stand and move on terrain with - Cleaning dust from the TMG/PSS enclosure different slope angles and to go up and down the ladder of the - Repair or replacement of TMG/PSS enclosure damaged Landing Module or Lunar/Martian base. Sand and loose rocks components. in combination with slopes will be encountered. While walking on uneven terrain, the crewmember may fall and When performing planetary exploration tasks, the suited injure himself. That is why, the protective measures listed crewmember must walk on uneven terrain. The PSS design below will be required in the PSS: must allow the crewmember to stand up after falling and take - Restriction of ankle joint mobility in order to prevent intermediate positions (on all fours, kneeling etc.), necessary dislocation of the crew member’s ankle joint to take the vertical position. The PSS enclosure must also - Use of dedicated pads inside the suit enclosure (e.g. on allow the suited crewmember to take different static postures knees) to take kneeling position without any pain without excessive effort. Moreover, the subject may need to - Use of rigid over-boots toes to prevent injures if the take these positions to complete a set of activities and suited crewmember drops anything on his feet exploratory tasks. This suggests a list of static postures at - Use of soft pads for chin and forehead in the helmet which the PSS joints should be in an equilibrium state (i.e. and/or pads-inserts on the headset. position maintained with little or no effort): - Standing up The PSS design must be coordinated with the mobile - Bending forward transportation system. The PSS design must support use of - Sitting Moon/Mars rovers, on the one hand, but on the other hand, the - On knee(s) Moon/Mars rovers must be designed with the PSS specific - On all fours. features taken into account. For different types of rovers, various means to seat the suited crewmember and provide In the process of planetary exploration, a cosmonaut/astronaut access to the controls are possible. It is also necessary to will be required to retrieve rock samples and the PSS foresee the possibility of the Moon/Mars rovers’ failure enclosure must accommodate this task. In order to reach the resulting in the astronaut/cosmonaut returning to the planet surface with a hand and take a sample of soil/rock, the base/landing module without using of any transportation crewmember must bend forward, squat, or kneel. Each of equipment. In this case, the maximum allowable distance these motions is implemented by interaction of a set of between the Moon/Mars rover and base must be determined, joints/bearings that is a specific feature of the PSS. taking into account the fact that the suited crewmember will have to return to the base on uneven terrain. The necessity to provide easy walking on the planetary surface is another specific requirement for the PSS. It is well known The members of the Martian expedition or lunar base that flexible-soled footwear makes walking easier. The issue occupants will have different anthropometrics and this fact concerning the definition of the degree of flexion of the sole must be kept in mind in developing the PSS design concept. It for the PSS boots must be studied. is necessary to provide PSS enclosure fit sizing over the required anthropometric range and/or selection of the optimal number of the suit component standard sizes. In the case of a lunar base, crew changes may make it desirable to resize the PSS for a significantly different build. This can be where the test subject weight decreases [3]. Under 1/6g, the accomplished if standard sizes of the PSS enclosure test subject posture corresponds to the posture presented in components are replaced by others and/or length readjustment Fig. 1. Under Mars conditions, where the gravitation is 1/3g, is possible. These operations should be easy and should not the joint flexion angles are approximately the same as those on take much time. the Earth for the man in a standing position. During testing in the “lunar” test facility it was also revealed that the suited The lifetime of separate components of the PSS (which will be crewmember’s metabolic rate level decreased when he worn out in the process of PSS operation) and the possibility matched the rate of his locomotion to the frequency of of repairing them are of great importance for these future EVA oscillations of the “man-suit-backpack with LSS” system. missions. The PSS should be designed in such a way as to radically decrease the time for its maintenance/repair. PSS The PSS enclosure construction must allow the suited maintenance/repair should be performed with the help of crewmember to rise/stand up after falling.