A Rocketdyne LR79 (S-3D) engine ignites during a Jupiter test launch at Cape Canaveral, Florida, in 1960. Note the coating of frost around the missile’s center, caused by cold liquid oxygen. (U.S. Air Force photo).
The LR79 rocket engine was a reliable workhorse for US Air Force space and missile launches between 1958 and 1980. This liquid-fueled engine powered Jupiter and Thor intermediate range ballistic missiles (IRBMs), Juno II satellite boosters, and Saturn I and IB rockets used in the Apollo, Skylab, and Apollo-Soyuz programs. Also known by its civilian designation S-3D, it delivered 150,000 pounds of thrust using kerosene and liquid oxygen.
Rocketdyne developed the basic S-3 engine in 1955-56 for the US Army. In 1956, Jupiter became an important Air Force missile when the USAF gained responsibility for all ballistic missiles with ranges of more than 200 miles. An S-3 engine powered a Jupiter on the first successful American IRBM test flight on May 3, 1957. In 1959, a Jupiter launched from Cape Canaveral, Florida, took two monkeys named Able and Baker on a 16-minute, 1,700-mile sub-orbital ride to an altitude of 360 miles. They were the first living beings successfully recovered after a space flight.
The S-3 engine design was refined and evolved into the S-3D that was used on later Jupiter, Thor, and Juno II satellite launchers between 1958 and 1962. A cluster of eight improved versions of the S-3D engine became the first-stage propulsion for NASA's Apollo Saturn I and Saturn IB in the late 1960s and early 1970s.