Zond 4

Zond 4, part of the Soviet Zond program and an uncrewed version of Soyuz 7K-L1 crewed Moon-flyby spacecraft, was one of the first Soviet experiments towards crewed 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.[1]

Zond 4

Names	Soyuz 7K-L1 s/n 6
Mission type	Lunar flyby Spacecraft test
Operator	OKB-1
COSPAR ID	1968-013A
SATCAT no.	03134
Spacecraft properties
Bus	Soyuz 7K-L1
Manufacturer	OKB-1
Launch mass	5,140 kilograms (11,330 lb)
Dimensions	4.5 m x 2.2 m x 2.72 m
Start of mission
Launch date	2 March 1968, 18:29:23 UTC
Rocket	Proton-K/D
Launch site	Baikonur 81/6
End of mission
Disposal	deorbited/destroyed
Decay date	7 March 1968 (1968-03-07)
Landing site	Gulf of Guinea
Orbital parameters
Reference system	Geocentric
Regime	Low Earth
Perigee altitude	192 kilometres (119 mi)
Apogee altitude	205 kilometres (127 mi)
Inclination	51.53°
Period	88.41 minutes
Zond

The spacecraft was successfully launched into a 354,000 km apogee orbit 180 degrees away from the Moon, It was launched away from the Moon probably to avoid trajectory complications with lunar gravity. However, on re-entry the L1's guidance system failed. It hit the atmosphere precisely at the calculated time, but was not guided to generate lift and fly out of the atmosphere again. A ballistic re-entry would mean no recovery on Soviet soil, so the APO destruct system automatically blew up the capsule at 10 to 15 km altitude, 180–200 km off the African coast at Guinea.

References

1. Huntress; Marov (2011). Soviet Robots in the Solar System: Mission Technologies and Discoveries. p. 172.

External links

• Astronautix.com Information on Lunar L1 program, including Zond 4