Portal:Spaceflight/On This Day/21 July
- 1961 - A Redstone rocket launches Mercury-Redstone 4 on a manned sub-orbital spaceflight.
- 1961 - A Thor-Agena fails to launch the Discoverer 27 satellite.
- 1962 - A Thor-Agena launches a CORONA satellite.
- 1967 - A Voskhod fails to launch an unknown satellite.
- 1969 - Apollo 11 astronauts Neil Armstrong and Buzz Aldrin become the first men to walk on the Moon.
- 1970 - A Voskhod fails to launch an unknown satellite.
- 1973 - A Proton-K launches the Mars 4 probe.
- 1976 - A Kosmos-3M launches the Kosmos 842 satellite.
- 1976 - A Tsyklon-2 launches the Kosmos 843 satellite.
- 1982 - A Kosmos-3M launches eight Strela satellites.
- 1982 - A Molniya-M launches a Molniya-1 satellite.
- 1988 - An Ariane 3 launches the Insat 1C/ECS 5 satellite.
- 1994 - A Long March 3 launches the Apstar 1 satellite.
- 2006 - A Molniya-M launches the Kosmos 2422 satellite.
- 2009 - A Kosmos-3M launches the Kosmos 2454 and Sterkh-1 satellites.
- 2012 - A H-IIB launches the HTV-3 logistics spacecraft to the International Space Station.