America’s oldest rocket just made its penultimate flight
The Delta II rocket first launched in 1989, making it the oldest US orbital launch system still flying today. However, the heritage of this launch system is much older still. The Delta II rocket's first stage is derivative of the Thor intermediate range ballistic missile—the first operational ballistic missile used by the United States Air Force in the 1950s. Thus, the Delta II rocket can trace its roots to the beginning of US rocketry.