| Kosmos 903 | |
| Mission Type: | Early warning |
| Cospar Id: | 1977-027A |
| Satcat: | 9911 |
| Mission Duration: | 4 years |
| Spacecraft Type: | US-K |
| Launch Date: | UTC |
| Launch Rocket: | Molniya-M/2BL |
| Launch Site: | Plesetsk Cosmodrome |
| Deactivated: | 8 June 1978 |
| Orbit Reference: | Geocentric |
| Orbit Regime: | Molniya |
| Orbit Inclination: | 62.8 degrees |
| Orbit Period: | 718.00 minutes |
| Apsis: | gee |
Kosmos 903 (Russian: Космос 903 meaning Cosmos 903) was a Soviet US-K missile early warning satellite which was launched in 1977 as part of the Soviet military's Oko programme. The satellite was designed to identify missile launches using optical telescopes and infrared sensors.
Kosmos 903 was launched from Site 43/3 at Plesetsk Cosmodrome in the Russian SSR. A Molniya-M carrier rocket with a 2BL upper stage was used to perform the launch, which took place at 01:38 UTC on 11 April 1977. The launch successfully placed the satellite into a molniya orbit. It subsequently received its Kosmos designation, and the international designator 1977-027A. The United States Space Command assigned it the Satellite Catalog Number 9911.
It was reported in History and the Current Status of the Russian Early-Warning System, that it self-destructed.
The primary portion of it re-entered on August 4, 2014, but several pieces of its debris still remain in orbit.[1]