Project Vanguard was a program of the U.S. Naval Research Laboratory. When
the agency launched Vanguard 1, it became the second artificial satellite to be
placed successfully in Earth orbit by the United States. It was the first solar-
powered satellite. It is the oldest satellite still in space, as it’s predecessors,
Sputnik 1, Sputnik 2, and Explorer 1, have fallen out of orbit.