Portal:Spaceflight/On This Day/4 April
- 1964 - A Vostok-2 rocket launches the Kosmos 28 satellite.
- 1967 - A Vostok-2 rocket launches the Kosmos 153 satellite.
- 1968 - A Saturn V launches the Apollo 6 spacecraft.
- 1969 - A Voskhod rocket launches the Kosmos 276 satellite.
- 1969 - A Kosmos-2I launches the Kosmos 277 satellite.
- 1971 - A Tsyklon-2 launches the Kosmos 404 satellite.
- 1972 - A Molniya-M launches a Molniya-1 satellite.
- 1974 - A Voskhod rocket launches the Kosmos 639 satellite.
- 1978 - A Soyuz-U launches the Kosmos-1001 satellite.
- 1983 - Space Shuttle Challenger makes its maiden flight, STS-6, launching the TDRS-1 satellite.
- 1984 - A Molniya-M launches the Kosmos 1547 satellite.
- 1986 - A Proton-K launches the Kosmos 1738 satellite.
- 1989 - A Kosmos-3M launches the Kosmos 2016 satellite.
- 1991 - A Proton-K launches three GLONASS satellites.
- 1991 - An Ariane 4 launches the Anik E2 satellite.
- 1997 - A Titan 23G launches a DMSP satellite.
- 1997 - Space Shuttle Columbia launches on STS-83, a Spacelab microgravity research mission.
- 2000 - A Soyuz-U launches the manned Soyuz TM-30 spacecraft, with the last crew to visit Mir.
- 2009 - An Atlas V launches the WGS-2 satellite.
- 2011 - A Soyuz-FG launches the manned Soyuz TMA-21 mission to the ISS.