Collection Item Summary:
One of several replicas and backup Explorer spacecraft in the collection. It is a full-size replica that consists of a machined metal shell of the payload section devoid of instrumentation, and is attached to a Sergeant, propellant-less, solid fuel rocket motor. It was transferred to the Smithsonian Institution by the Army Ballistic Missile Agency in September 1958. Explorer-1, also known unofficially as Satellite 1958 alpha, was the first American satellite to orbit the earth.