This model of unknown scale depicts one of the early versions of the Delta rocket, developed by Douglas Aircraft for the National Aeronautics and Space Administration beginning in 1959. The early version utilized a modified first stage from the Air Force's Thor intermediate-range ballistic missile and a modified second stage from the Navy's Vanguard rocket. In May 1960, the first Delta successfully launched an Echo I communications satellite into orbit. Through the years, the Delta has been continually upgraded and it has launched a number of civilian and military payloads. The model's manufacturer and donor are unknown at this time.