Mars 4 (M-73 Orbiter #1), a Soviet Lavochkin Mars orbiter, first of the 1973 Mars quartet. Proton-K Blok-D from Baikonur LC-81/23 launched on 21 July 1973; its retro-engine later failed, so the craft flew past Mars instead of entering orbit and returned limited flyby imagery.
- Outcome
- Success
- Orbit
- Mars
- Payload to orbit
- 3.4 T (est.)
- Flight
- 31st
- of 38 Proton / UR-500 K/D flights
- Date and time
- 21 July 1973, 19:30 UTC
- Rocket
- Proton / UR-500 K/D
- Builder
- Khrunichev
- Launch site
- 81/23 (81L), Baikonur Cosmodrome, Republic of Kazakhstan
- Payload
- Robotic Exploration
- International designator
- 1973-047
- Launches in 1973
- 53rd of 116
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Space Atlas shows the satellites and rocket stages from this launch in 3D.
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