Atlas G

The Atlas G, also known as Atlas G Centaur-D1AR, was an American expendable launch system derived from the Atlas-Centaur and used to launch seven communication satellites in the mid to late 1980s. It combined an improved Atlas core, with modernised avionics and propellant tanks stretched by 81 inches, with an updated Centaur D-1AR upper stage. The first stage used the new MA-5 engine section, which raised thrust by 7,500 pounds-force, and kept the thin stainless steel balloon tanks of earlier Atlas rockets that had to stay pressurised to avoid collapsing. The Centaur gained a hydrazine reaction control system and improved RL10 engines. All seven launches flew from Launch Complex 36B at Cape Canaveral, aiming for geostationary transfer orbit. The maiden flight, carrying Intelsat 5 on 9 June 1984, was lost when the Centaur oxygen tank split during the coast phase. The Atlas G was replaced by the near-identical Atlas I, which had an improved guidance system and a larger fairing, and its first stage also flew alone as the Atlas H.