The Explorer program was the United States' first successful attempt to launch
unmanned space missions. It began as an attempt to place an artificial satellite into orbit during the [International Geophysical Year]
?, and became an attempt to catch up with the
Soviet Union after that nation's launch of
Sputnik I on
October 4,
1957.
Explorer I was launched on January 31, 1958 and attained Earth orbit. Its instruments detected the [Van Allen radiation belts]?.
(other craft in the Explorer program here)
![[Home]](wikipedia.png)