Answer: When it was sent to orbit on January 31, 1958, Explorer 1 became the first successfully launched spacecraft by the United States. A rapid reaction to the launch of Sputnik 1 by the Soviet Union, Explorer 1's success signaled the beginning of the U.S. The Spatial Period. It was launched due to the Cold War. (1947-1991)
Explanation:
Hope this helps a little! :)
