Thor-Able

Thor-Able was an American expendable launch system flown between 1958 and 1960 for re-entry vehicle tests and for early spacecraft launches. It stacked a Thor intermediate-range ballistic missile as its first stage with a second stage derived from the Vanguard programme, called Able, and for probe and satellite launches it added an Altair solid rocket motor as a third stage. The Thor-Able airframe was stronger than the standard missile, and the inertial guidance of the Thor was replaced with a radio guidance package carried on the Able stages. Sixteen were launched from Cape Canaveral, nine on sub-orbital test flights, four on probes and three on orbital attempts, and six of the flights failed. Its flights carried the mouse nose cone tests, Pioneer 1, Pioneer 2 and Pioneer 5, Explorer 6 and the Tiros-1 weather satellite, and it is an early predecessor of the Delta family of rockets.