Sputnik 1
Date: 4 Oct 1957

The Sputnik 1 (PS-1) satellite is shown here on a rigging truck in the assembly shop in the fall of 1957 as a technician puts finishing touches on it.

When the development of the first advanced scientific satellite, Object D, proved to be more difficult than expected, the Soviets decided to launch a simpler, smaller satellite. PS-1, or Sputnik 1, began development in November 1956.

On 4 October 1957, Sputnik 1 successfully launched and entered Earth's orbit. Sputnik shocked the world, giving the USSR the distinction of putting the first human-made object into space and putting the United States a step behind in the space race.

Credit: NASA