Soyuz 7K-L1

The Soyuz 7K-L1 "Zond" spacecraft was designed to launch cosmonauts from the Earth to circle the Moon without going into lunar orbit in the context of the Soviet crewed Moon-flyby program in the Moon race. It was based on the Soyuz 7K-OK. Several modifications reduced vehicle mass and increased circumlunar capability. The most notable modifications were the replacement of the orbital module with a support cone and a high-gain parabolic antenna, the removal of a reserve parachute, and the addition of the gyro platform and star navigation sensors for the far space navigation. The spacecraft was capable of carrying two cosmonauts. At the start of flight testing, there were serious reliability problems with the new Proton rocket, the 7K-L1, and the Soyuz 7K-OK that the L1 was based on.