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physical sources in space on the magnetic field lines linking 

 them to ground points. 



A satellite situation center at Goddard Space Flight Center 

 provided real time positions of spacecraft of all nations so 

 that scientists could relate the measurements at critical times 

 in the crossings of magnetospheric boundaries. Out of the 

 random sampling of previously uncoordinated space probing 

 emerged a clear pattern of signals sharply delineated in space 

 and time. By grasping the obvious opportunities for 

 cooperation, the value of the scientific product was multiplied 

 enormously. 



The roster of spacecraft that contributed to the IMS 

 included three prime U.S./E.S.A missions, International Sun 

 Earth Explorers (ISEE), I, II, and III. Other contributing 

 spacecraft were IMP-7 and 8, Atmospheric Explorer E, NOAA GOES, 

 DoD's SOLRAD 11-A, and 11-B, Japan's ISS and EXOS-B. The 

 U.S.S.R. brought in four of their Space Institutes, as well as 

 their counterparts in Czechoslovakia, Bulgaria, the German 

 Democratic Republic and Hungary. Their missions included a 

 low-altitude circular orbit satellite, a high altitude 

 elliptical orbit satellite and various interplanetary explorer 

 satellites. A rough estimate puts the U.S. investment at about 

 20-25 percent of the total. In addition to providing the EXOS 

 satellites, Japan spent about $22 M on peripheral ground based 

 components. Altogether, scientists in about 50 countries were 

 active in the program. 



