DESIGN IMPLICATIONS FOR EXTRAVEHICULAR ACTIVITY Rani Lueder Steel case Grand Rapids, Michigan ABSTRACT Extravehicular Activity (EVA) is consldered paramount to achievement of missfon objectives of the space program and a, trend of both increased and more diversified farm of EVA is expected. This trend wi17 require many alternat$ve design configurations of EVA suits according to relative priorities of various issues. Some of these issues are discussed (heat5ng/cooling, protectton from ionizing radiation, denitrogenation, visual protection, comfort/dexteri ty). Previous sol u- tions of the U.S. space program are described. INTRODUCTION The botlrgeoning international emphasis on space programS, Tncluding the recent U.S. Space Shuttle flight has awa kened many to the enormous potential available in spdce. As new t e c h n o l o g f e s and new a p p l i c a t i o n s to old technologi'es are developed the impetus for space utiliz~tiqn will be increasingly provided by both the regulatory and private sectors- This will represent a greater diversification of spacecraft ahd a correspondingly increased range of operational demands'and objectives. Extravehicular Activities (WAS) are f~ndamental to the success of these objectives and a trend of greater use of EVA i s expected (Griswolde ar.d Wilde, 1981).. An emphasis on reduced dependence on massive ground stations through the use of improved computer systems and minimization of use of expendables (National Aeronautics and Space Admtnistration, 1979) will promise grearer autonomy and operatjonal potential for EVA. Although NASA has had an ongoing fnterest in the use nf teleaperators and robotics (advanced forms of teleop- erators that funct$on autonorno~~ly or semizutonomously) ths2e are likely to extend rather than replace human capabilities due to the unstructurcd and nonrepetitive nature of many EVA tasks (National AerbnaLFtics and Space Adrninfstration, 197b). EVA capability is currently baselin& for NASA's future Shuttle missions, each operational Orbiter mi$- $ion prdvfdin$.for three two-man EVA5 of seven hour duratfons as standard procedure. EVA represents persomed activity performed in a space suit and in a near vacuum enutronment. EVA is the only means to guarantee rescue of crews from stranded Orbiters (Brouillet, 1981). In the next decade EVAs will largely constitute tasks such as Inspection, repair and deploy- ment of satellites. Beam building.wil1 subsequently become important and i s expected to incur approximately 50% of the working hours in space (Gunkel and Wolbers. 1977). Eventual 1 y EVAs wi 11 assume greater correspon- dence to work characteristic of industrial societies on earth and with greater task specifiiity (American Institute of Aerooautics and Astronautics. 197qJ. Demands will include long tern) and short tem tasks at fixed and temporary worksites at zero g in free space and a t varying g factors on lunar aud planetary sur- faces, during light and dark per5ods and different thermal environments. Different degrees of sk$ll, strength, and dexterity will be required. Workers will drffer substantially in such characteristics as motiva- tion, training and socio-cultural bdckground. As space utilization becomes the norm and rrtissions increase in duration aqe-related issues my play an increasing role in design decfsiuns. Consequently, in the future there will not be any one desIgn solution for EVA suits and equipment. Rather, a number of issues must be consid- ered of vary<ng levels of priority according to crew- member characteristics and mission objectives, Some basic attributes of EVA suits will be described as web as issues for future design applicatSons. EXTRAVEHICULAR MOBILITY UNIT The two arimary EVA suits designed for NASA's space program were the Apollo and Space Shuttle suits. Gemini's EVA5 were conducted in a modified Air Force high altitude flying suit and suffered a number of constraints, particularly in mobility and visor fogging (~roulllet and Griswolde, 1981). The Skylab EVA suit was substantially the same as the Apollo suit with an improved visor assembly and an urnbflically supplied life support (pressure, oxygen, ventilation and cooling). These suits were termed Extravehicular Mobility Units (EMU$). The Apollo EMU consisted of two primary subsystems (Carson, Rouen, Lutz and McBarron, 1975). The Pressure Garment Assembly (PGA) had to be custom buflt for each astronaut. The central components of this assembly were the undergarments which contained tubes for circulation of water for coolifig and the soft multilamlnate outer garment serving PS a pressure garment, thermal insulator and some degree of micrometeoroid protection. Dfpped rubber convoluted joints were provided with restra$nt cables to prevent ballooning under pressure. Included in this assembly was a communications cap with earphones and microphon~s, birhble helmet, EVA ovw-rf $or assembly, gloves, drink bag and body waste collect~on devSce. The second primary system. the Portable Life Support System (PLSS) was a backpack assembly that supplied breathing oxygen, purified oxygen by removal of carbon