Explorer 1 (also known as satellite 1958 Alpha) was the first Earth satellite of the Unite States, launched on February 1, 1958 at 03:48 UTC from LC-26 at Cape Canaveral Air Force Station as part of the United States program for the International Geophysical Year and in response to the launch of the Soviet satellite Sputnik 1. It was the first spacecraft to detect the Van Allen radiation belt.