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In addition to hydrographic cooperation, DMA 

 participates in joint ventures with NOS ' s Coast & Geodetic 

 Survey (C&GS) in the geodesy and geophysics (G&G) fields. 

 DMA computes and publishes the official DoD precise orbits, 

 or ephemerides, for the Global Positioning System (GPS) 

 satellites. C&GS has also developed the capability to 

 generate GPS ephemerides for the civil sector. DMA continues 

 to provide C&GS with GPS data and ephemerides so that C&GS 

 can verify their computations. In addition, DMA has supplied 

 gravity data from the DcD Gravity Library and has loaned C&GS 

 a significant number of gravity meters in order to assist in 

 the development of a highly accurate geoid, the theoretical 

 mean sea level as defined by the gravity field of the earth, 

 in the United States. DMA funded the development of the 

 first portable absolute gravity meter, jointly purchased one 

 of these meters, and turned it over to C&GS for operation. 

 Absolute gravity measurements support a number of programs, 

 including global climatology. DMA is assisting C&GS in its 

 program to position airfields in the South Pacific Islands 

 for the Federal Aviation Administration. G&G program 

 managers from DMA and C&GS are constantly communicating about 

 projects of potentially mutual interest. 



III. Cooperative Development Efforts which Potentially 

 Benefit the Civil Sector. 



DMA has two cooperative development efforts presently 

 underway with NOAA to benefit DoD and civil marine navigation 

 and, potentially, also the scientific community. These 

 initiatives are the Digital Nautical Chart Production Program 

 and the Defense Hydrographic Initiative. A third DMA 

 development effort, the Hydrographic Data Recording System, 

 offers potential for mutually beneficial cooperation with 

 NOAA, the U.S. Coast Guard, and the civilian maritime 

 community . 



73-766 0-94-4 



