 The Salyut programme begun on 15 February 1970 on the condition that the crewed lunar program would not suffer.However, the engineers at OKB-1 perceived the L3 lunar lander effort as a dead-end and immediately switched to working on DOS.In the end it turned out that the Soviet N1 "Moon Shot" rocket never flew successfully, so OKB-1's decision to abandon the lunar program and derive a DOS space station from existing Soyuz subsystems and an Almaz/OPS hull proved to be right