But the USSR lost its early lead after US president John F. Kennedy raised the stakes by setting a goal of "landing a man on the Moon and returning him safely to the Earth". American spaceflight capability overtook that of the Soviets with flights up to two weeks long; two craft meeting in space (rendezvous) and joining (docking); astronauts working outside spacecraft; and using high-energy liquid hydrogen as rocket fuel in the Saturn family of rockets. Kennedy's Moon landing goal was acheived in July 1969, with the flight of Apollo 11, which sent and returned three men and landed two of them, a singular achievement far outweighing any combination of Soviet achievements. The USSR pursued two crewed lunar programs, but failed to develop a launch vehicle powerful enough to land one human on the Moon before the US, and eventually canceled them to concentrate on Earth orbital space stations, while the US landed five more Apollo crews on the Moon.