 The N1 rocket suffered four catastrophic uncrewed launch failures between 1969 and 1972, and the Soviet government officially discontinued its crewed lunar program on June 24, 1974, when Valentin Glushko succeeded Korolyov as General Spacecraft Designer.Both nations went on to fly relatively small, non-permanent crewed space laboratories Salyut and Skylab, using their Soyuz and Apollo craft as shuttles.The US launched only one Skylab, but the USSR launched a total of seven "Salyuts", three of which were secretly Almaz military crewed reconnaissance stations, which carried "defensive" cannons.