Portal:Spaceflight/On This Day/21 September
- 1971 - A Voskhod launches the Kosmos 439 satellite.
- 1973 - A Soyuz-U launches the Kosmos 587 satellite.
- 1976 - A Soyuz-U launches the Kosmos 855 satellite.
- 1981 - A Tsyklon-3 launches the Aureole 3 satellite.
- Galaxy 3satellite.
- 1994 - A Proton-K launches the Kosmos 2291 satellite.
- 2000 - A Titan 23G launches the NOAA-16 satellite.
- payload.
- 2010 - An Atlas V launches the USA-215 reconnaissance satellite.
- Ariane 5 ECA launches the Arabsat 5C and SES-2satellites.