| Kosmos 104 | |
| Names List: | Zenit 2-33 |
| Mission Type: | Optical imaging reconnaissance |
| Operator: | OKB-1 |
| Cospar Id: | 1966-001A |
| Satcat: | 1903 |
| Spacecraft Type: | Zenit-2 |
| Manufacturer: | OKB-1 |
| Launch Mass: | 4730 kg[1] |
| Launch Date: | 7 January 1966 08:24:00 GMT |
| Launch Rocket: | Vostok-2 |
| Launch Site: | Baikonur 31/6 |
| Launch Contractor: | OKB-1 |
| Disposal Type: | Recovered |
| Landing Date: | 15 January 1966 |
| Orbit Epoch: | 7 January 1966 |
| Orbit Reference: | Geocentric[2] |
| Orbit Regime: | Low Earth |
| Orbit Periapsis: | 193 km |
| Orbit Apoapsis: | 380 km |
| Orbit Inclination: | 65.0° |
| Orbit Period: | 90.2 minutes |
| Apsis: | gee |
| Programme: | Zenit programme Zenit-2 |
| Previous Mission: | Zenit 2-32 |
| Next Mission: | Zenit 2-34 |
| Programme2: | Kosmos (satellites) |
| Previous Mission2: | Kosmos 103 |
| Next Mission2: | Kosmos 105 |
Kosmos 104 (Russian: Космос 104 meaning Cosmos 104) or Zenit-2 No.33 was a Soviet first-generation low-resolution optical film–return reconnaissance satellite launched in 1966. A Zenit-2 spacecraft, Kosmos 104 was the thirty-second of eighty-one such satellites to be launched[3] and had a mass of 4730kg (10,430lb).
Kosmos 104 was launched by a Vostok-2 rocket[4] from Site 31/6 at the Baikonur Cosmodrome. The launch took place at 08:24 GMT on 7 January 1966;[5] however, the program was not completely met. The spacecraft was put into an incorrect orbit by malfunctions in the booster rocket's second and third stages.[6] The spacecraft received a Kosmos designation, along with the International Designator 1966-001A and the Satellite Catalog Number 01903.[7]
Despite the problem during its launch, Kosmos 104 was able to complete most of its imaging mission. Its orbit, at an epoch of 7 January 1966, had a perigee of 193km (120miles), an apogee of 380km (240miles) inclination of 65.0° and a period of 90.2 minutes.[8] On 15 January 1966, after eight days in orbit, the satellite was deorbited with its return capsule descending by parachute for a successful recovery by Soviet force.[9]