Initially, the Mars 5NM and the Mars 4NM missions were proposed in 1970s with the launch of a super-heavy N1 rocket. The rocket was to launch in 1975 with a Mars landing in 1977. But in 1973, due to the failure of the N-1, this project was cancelled.
A new project was designed, based on heavy Proton rocket: a double launch and a dock in Earth orbit for a joint flight of Mars 5M components to Mars. The return capsule, which would weigh 8.7 kg, would contain 500 g of martian soil sample. The project was approved in early 1974 for a take-off in 1979. Tests were conducted but the docking system, Igla, a critical component of the mission, has experienced failures: Soyuz 25 failed to dock with the Salyut-6 space station. The government's attitude to this project changed. A report denouncing the whole enterprise as highly uncertain was published and in 1978, Mars 5M was cancelled. All the models were destroyed.