Zond 4

Description

Zond 4 was launched to a distance of 300,000 km from Earth. The purpose of the mission was to explore circumterrestrial space and to flight test new systems and equipment. The launch was made in a direction away from the Moon. Zond 4 was a 7K-l1 spacecraft comprising a propulsion module, service module, and re-entry module. Designed for a two astronaut crew, it was similar to the later Zond 5 in design, a cylindrical capsule approximately 4.5 meters in length and 2.2 to 2.72 meters in diameter, with two solar panels attached on opposite sides of the body spanning a total of about 9 meters. The spacecraft carried proton detectors and radio test relays among its instrumentation. Unlike the earlier Zond spacecraft, this was designed ot hold a crew. This mission was an uncrewed test of the capsule and a planned precursor to crewed missions.

Zond 4 was launched into Earth parking orbit as part of a Tyazheliy Sputnik (68-013B) station by the SL-12/D-1-e UR-500K Proton launcher. A Block D fourth stage put the probe out to 300,000 km distance. Its return to Earth was supposed to be made by a skip re-entry, but apparently the re-entry capsule failed to separate from the service module and the angle of attack was too steep. The spacecraft entered at high speed over West Africa. Ground control set off the self-destruct mechanism over the Gulf of Guinea at an altitude of 10 km.

The trajectory away from the Moon was probably unintentional (although some claims were made that it was aimed away from the Moon to avoid complications of lunar gravity). The spacecraft supposedly could not be sent towards the Moon because of a malfunction in the attitude control system. On Earth, cosmonauts Popovich and Sevastyanov communicated from an isolated bunker with Yevpatoriya Flight Control Center in the Ukraine via a relay on board the spacecraft to simulate communications between cosmonauts in space and the ground controllers on Earth.