The Atlas rocket became a very reliable booster for launching of satellites and continued to evolve, remaining in use into the 21st century, when combined with the Centaur upper stage to form the Atlas-Centaur launch vehicle for launching geosynchronous communication satellites and space probes. The Centaur rocket was also designed, developed, and produced by Convair, and it was the first widely used outer space rocket to use the all-cryogenic fuel-oxidizer combination of liquid hydrogen and liquid oxygen. The use of this liquid hydrogen – liquid oxygen combination in the Centaur was an important direct precursor to the use of the same fuel-oxidizer combination in the Saturn S-II second stage and the Saturn S-IVB third stage of the gigantic Saturn V moon rocket of the Apollo program. The S-IVB had earlier also been used as the second stage of the smaller Saturn IB rocket, such as the one used to launch Apollo 7. The Centaur upper stage was first designed and developed for launching the Surveyor lunar landers, beginning in 1966, to augment the delta-V of the Atlas rockets and give them enough payload capability to deliver the required mass of the Surveyors to the Moon.