|Mission type||Optical imaging reconnaissance|
|Mission duration||8 days|
|Launch mass||4730 kg |
|Start of mission|
|Launch date||19 January 1967|
|Rocket||Vostok-2 s/n N15001-05|
|Launch site||Plesetsk, Site 41/1|
|End of mission|
|Landing date||27 January 1967|
|Reference system||Geocentric |
|Perigee altitude||191 km|
|Apogee altitude||273 km|
|Epoch||19 January 1967|
Kosmos 138 (Russian: Космос 138 meaning Cosmos 138) or Zenit-2 No.43 was a Soviet, first generation, low resolution, optical film-return reconnaissance satellite launched in 1967. A Zenit-2 spacecraft, Kosmos 138 was the forty-fifth of eighty-one such satellites to be launched and had a mass of 4,730 kilograms (10,430 lb).
Kosmos 138 was launched by a Vostok-2 rocket, serial number N15001-05, flying from Site 41/1 at the Plesetsk Cosmodrome. The launch took place at 12:39:59 GMT on 19 January 1967, and following its arrival in orbit the spacecraft received its Kosmos designation; along with the International Designator 1967-004A and the Satellite Catalog Number 02646. The satellite reached a slightly lower orbit than had been planned, but was still able to complete its mission.
Kosmos 138 was operated in a low Earth orbit, at an epoch of 19 January 1967, it had a perigee of 191 kilometres (119 mi), an apogee of 273 kilometres (170 mi), an inclination of 65.0°, and an orbital period of 89.2 minutes. After 8 days in orbit, Kosmos 138 was deorbited, with its return capsule descending under parachute, landing at 06:14 GMT on 27 January 1967, and recovered by Soviet force.