When United Launch Alliance’s final Delta II rocket deploys NASA’s ICESat-II satellite on Saturday, the launch will bring down the curtain not just on the Delta II’s own illustrious career, but also on a series of rockets dating back to the early days of the space race. Delta II is the ultimate evolution of the US Air Force’s Thor missile, which first flew in 1957 and stood watch in Britain against Soviet aggression from 1959 to 1963.
