Mars M-69 No.521, a Soviet Mars orbiter built by NPO Lavochkin, launched on a Proton-K/Blok D from Baikonur Site 81/23; payload fairing failure and third-stage ignition failure prevented the probe from reaching orbit.
- Outcome
- Failure
- Orbit
- Mars
- Payload to orbit
- Did not reach orbit
- Flight
- 11th
- of 38 Proton / UR-500 K/D flights
- Date and time
- 27 March 1969, 10:40 UTC
- Rocket
- Proton / UR-500 K/D
- Builder
- Khrunichev
- Launch site
- 81/23 (81L), Baikonur Cosmodrome, Republic of Kazakhstan
- Payload
- Robotic Exploration
- Launches in 1969
- 35th of 125