events
Explorer program: Explorer 4 is launched.
Related Wikipedia articles
Explorers Program
Ongoing NASA space exploration program
The Explorers Program is a NASA exploration program that provides flight opportunities for physics, geophysics, heliophysics, and astrophysics investigations from space. Launched in 1958, Explorer 1 was the first spacecraft of the United States to achieve orbit. Over 90 space…Source: Wikipedia (CC BY-SA)
Explorer 4
Satellite launched by the United States (1958)
Explorer 4 was an American satellite launched on 26 July 1958. It was instrumented by Dr. James van Allen's group. The Department of Defense's Advanced Research Projects Agency (ARPA) had initially planned two satellites for the purposes of studying the Van Allen radiation belts…Source: Wikipedia (CC BY-SA)