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SPACE STATTOBI F R E E D O H H89-24439L o r r a L. R i e k e r and F r a n c i s M. Haraburda N a t i o n a l A e r o n a u t i c s and Space A d m i n i s t r a t i o n Lewis Research C e n t e r C l e v e l a n d , O h i o 44135 ABSTRACTThe N a t i o n a l A e r o n a u t i c s and Space A d m i n i s t r at i o n has adopted t h e p o l i c y t o a c h i e v e t h e maximum p r a c t i c a l l e v e l o f commonality f o r t h e Space Stat i o n Freedom program i n o r d e r t o s i g n i f i c a n t l y reduce l i f e c y c l e c o s t s . Commonality means u s i n g i d e n t i c a l o r s i m i l a r h a r d w a r e / s o f t w a r e f o r m e e t i n g common s e t s o f f u n c t i o n a l l y s i m i l a r r e q u i r e m e n t s . P r e s e n t e d i n t h i s paper i s i n f o r m a t i o n on how t h e c o n c e p t o f commonality i s b e i n g implemented w i t h r e s p e c t t o e l e c t r i c power system hardware f o r t h e7 Space S t a t i o n freedom and t h e U.S. P o l a r P l a t f o r m . I n c l u d e d i s a h i s t o r i c a l a c c o u n t o f t h e c a n d i d a t e common i t e m s which have t h e p o t e n t i a l t o serve t h e same power system f u n c t i o n s on b o t h freedom and t h e P o l a r P l a t f o r m . PROGRAM DESCRIPTION AND OBJECTIVESTwo o f t h e Space S t a t i o n Freedom program o b j e c t i v e s a r e t o e s t a b l i s h a p e r m a n e n t l y manned r e s e a r c h f a c i l i t y i n l o w -E a r t h o r b i t and t o p r ov i d e an unmanned p l a t f o r m for l o n g d u r a t i o n s c i e nt i f i c and o p e r a t i o n a l o b s e r v a t i o n s i n n e a r -p o l a r o r b i t .I n o r d e r t o b r i n g t h i s a b o u t , t h e t e s t and development r e s p o n s i b i l i t i e s f o r t h e program e l ements t h a t form t h e s e f a c i l i t i e s a r e d i s t r i b u t e d among f o u r NASA c e n t e r s -M a r s h a l l Space F l i g h t C e n t e r (MSFC), Johnson Space C e n t e r (JSC), Goddard Space F l i g h t C e n t e r (GSFC), and Lewis Research Cent e r (NASA L e w i s ) . T h i s a l l o w s t h e p r o g r a m t o draw upon u n i q u e s k i l l s and r e s o u r c e s t h r o u g h o u t t h e agency. O v e r a l l program d i r e c t i o n and system e n g in e e r i n g and i n t e g r a t i o n ( S E & I ) a c t i v i t y i s t o be p r o v i d e d by t h e Program O f f i c e ( L e v e l 11) i n Reston, VA ( F i g . 1 ) .GSFC and i t s p r i m e c o n t r a c t o r General E l e c t r i c , has t h e r e s p o n s i b i l i t y for t h e d e f i n i t i o n , development, u t i l i z a t i o n , and s e r v i c i n g o f p l a t f o r m s . I n i t i a l l y t h e r e were two p l a t f o r m s i n Phase I of t h e program, a p o l a r p l a t f o r m and a c o o r b i t i n g p l a t f o r m . The l a t t e r , p l a n n e d t o occupy a l o w -E a r t h o r b i t t h e same as t h e space s t a t i o n , has been s h i f t e d downs t r e a m t o Phase I 1 o f t h e space s t a t i o n program. W h i l e ...