193 



U.S.A. 



ASTROPHYSICS EXPLORERS 

 NASA 



"Big Science" Descriptor : Space: physics and astronomy 



Description of Facility/Instrument : EXPLORER projects for x-ray, 

 gaooa-ray, and ultraviolet ray explorations. 



Date of Construction : 1961-1983 (launches) 



Construction Cost : 1984 $$ : Total cost undetermined 



Present International Cooperation 



Nationality(s) of Ownership : D.S. (Except where 



Nationallty(s) of Operational Funding : U.S. international 



Hatlonallty(s) of Management Staff : U.S. cooperation 



Nationallty(s) of Researchers : U.S. is noted below.) 



Other Information : X-RAY ASTRONOMY EXPLORERS: EXPLORER 42 was launched 

 from Kenya in 1970. EXPLORER 53, launched in 1975, successfully 

 broadened the knowledge of x-ray sources, discovering 200 when 40 

 had been known previously. EXPLORERS 42 and 53 also are known 

 as SAS-1 and SAS-3, respectively. 



Two international cooperative ventures in this field were the 

 Astronomical Netherlands Satellite (ANS), launched in 1974, and 

 the Ariel 5 (U.S.-U.K.), launched in 1974, which broadened the 

 knowledge of "bursters," new x-ray sources and ultra-violet 

 emissions. 



GAMMA-RAY ASTRONOMY EXPLORERS: EXPLORER 11 (1961) and 

 EXPLORER 48 (1972) both relayed data on gamma-ray emissions from 

 the cosmic background and gamma-ray point sources. EXPLORER 48 

 also investigated cosmic ray gas and the Vela supernova remnant. 



RADIO ASTRONOMY EXPLORERS: EXPLORER 38 (also known as RAE-1, 

 1968) and EXPLORER 49 (also known as RAE-2, 1973) were to map out 

 the galaxy in the 10 to 400 megahertz region, which cannot be 

 studied from Earth. The satellites also have provided information 

 on cosmic background noise, solar radio bursts, and radio emissions 

 from Earth. 



ULTRAVIOLET ASTRONOMY EXPLORERS: The International Ultra- 

 violet Explorer (lUE), launched in 1978, is still operational, at 

 a total cost of $37 million. Primarily a U.S. venture, this Is 

 also a cooperative venture with the British Science Research 

 Council and the European Space Agency (ESA). The satellite is 

 used to determine the various spectra of hot stars, cool stars, 

 the Interstellar medium, x-ray sources, extragalactic objects. 



