Soyuz 7K-L1

The Soyuz 7K-L1, publicly called Zond, was a Soviet spacecraft designed to carry cosmonauts around the Moon and back to Earth without entering lunar orbit, as part of the Soviet crewed lunar flyby effort in the Moon race. It was based on the Soyuz 7K-OK, with changes that cut mass and raised its circumlunar capability: the orbital module was replaced by a support cone and a high-gain parabolic antenna, the reserve parachute was removed, and a gyro platform and star navigation sensors were added for deep space navigation. It could carry two cosmonauts. Early flight testing suffered reliability problems with the new Proton rocket and the spacecraft itself. All L1 craft flew uncrewed between 1967 and 1970, and the planned first crewed flight, with Alexei Leonov and Valery Bykovsky, was cancelled.