Zond 4
 Zond 4 a formal component of the Soviet Zond program and unmanned version of Soyuz 7K-L1 manned Moon-flyby spacecraft was one of the first Soviet experiments towards manned circumlunar spaceflight. It was launched to test the spaceworthiness of the new capsule and to gather data about flights in circumterrestrial space. It was the first Soviet spacecraft to possess a computer the 34 kg Argon 11.