221 



U.S.A. 



SOLAR-TERRESTRIAL EXPLORERS 

 NASA 



"Big Science" Descriptor : Space: earth science 



Description of Facility/Instrument : These were the EXPLORER missions 

 which had Earth-oriented and solar-oriented purposes 



Date of Construction ; Launches began in 1959; many still are 

 operational 



Construction Cost ; 1984 $$ : Total cost undetermined 



Present International Cooperation 



Nationality(s) of Ownership ; (U.S. with some inter- 



Nationallty(s) of Operational Funding ; national cooperation 



Nationality(s) of Management Staff : as discussed in detail 



Nationallty(8) of Researchers ; below.) 



Potential for Future International Cooperation : See below. 



Other Information ; 



AIR DENSITY EXPLORERS 



EXPLORERS 9 (launched 1961), 19 (1963), 24 (1964), and 39 

 (1968) were 12-foot Inflatable spheres designed to measure the 

 upper atmosphere and lower exosphere and to determine air density 

 as a function of latitude, season, and local solar time. 



ATMOSPHERE EXPLORERS 



Five U.S. ATMOSPHERE EXPLORERS [EXPLORERS 17 (launched 1963), 

 32 (1966), 51 (1973), 54 (1975), and 55 (1975)] and eight inter- 

 national satellites [U.K. -U.S.: ARIEL 2 (1964), 3 (1967), 4 

 (1971); Italy-U.S.: SAN MARCO 1 (1964), 2 (1967), 3 (1971), 4 

 (1974); and U.S. -Federal Republic of Germany: AEROS (1972)] were 

 designed to collect temperature composition density and pressure 

 data to permit the study of the physics of the atmosphere. 



ENERGETIC PARTICLE EXPLORERS 



Four EXPLORER missions [EXPLORER 12 (launched 1961), 14 

 (1962), 15 (1962), and 26 (1964)] were designed to study injection 

 trapping and loss mechanisms of the Earth's radiation belts. 

 International cooperation projects for similar purposes were 

 conducted with the United States by the European Space Agency 

 (ESA) [ESRO IIA (launched 1967), and ESRO IIB (1968)] and the 

 Federal Republic of Germany [AZUR (1969)]. 



