 | |
| Names | Soyuz 7K-L1 s/n 6 |
|---|---|
| Mission type | Lunar flyby Spacecraft test |
| Operator | OKB-1 |
| COSPAR ID | 1968-013A |
| SATCATno. | 03134 |
| Spacecraft properties | |
| Bus | Soyuz 7K-L1 |
| Manufacturer | OKB-1 |
| Launch mass | 4,425 kilograms (9,755 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 | Baikonur81/6 |
| End of mission | |
| Disposal | deorbited/destroyed |
| Decay date | 9 March 1968 (1968-03-09) |
| Orbital parameters | |
| Reference system | Geocentric |
| Regime | Elliptical orbit |
| Perigee altitude | 200 kilometres (120 mi) |
| Apogee altitude | 400,000 kilometres (250,000 mi) |
| Inclination | 51.53° |
Zond 4, part of the SovietZond program and an uncrewed version ofSoyuz 7K-L1 crewed Moon-flyby spacecraft, was one of the first Soviet experiments towards crewed circumlunar spaceflight. It was launched to test thespaceworthiness of the new capsule and to gather data about flights incircumterrestrial space. It was the first Soviet spacecraft to possess a computer, the 34 kg Argon 11.[1]
The spacecraft was successfully launched by a Proton D-1e on 2 March 1968 into a 400,000 km apogee orbit 180 degrees away from the Moon.[2] 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 theAfrican coast atGuinea.[1]
The Zond 4 flight was in some ways similar to the AmericanApollo 4 and6 missions as they were uncrewed test flights in highly elliptical Earth orbits.[3]
| 3MV based missions | | |
|---|---|---|
| Soyuz 7K-L1/L1S | ||
| Other | ||
| Launch vehicles and ascent/upper stages |  | |
|---|---|---|
| Spacecraft | ||
| Other hardware | ||
| Soyuzdocking tests | ||
| Zond (7K-L1/L1S) lunar flyby missions | ||
| LOK (7K-LOK/L1E) test missions | ||
| LK Lander (T2K) test missions | ||
The † sign designates failed missions.Italics designates cancelled missions. | ||
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