Surveyors

Launched on 20 September 1966 by an Atlas-Centaur, Surveyor 2 was lost when one of its three thrusters failed to ignite for the 10-second mid-course correction 16 hours later, and the asymmetric thrust set the vehicle tumbling. It crashed onto the Moon on 23 September.1 The transmission from Surveyor 4 ceased on 17 July 1967, two seconds before its retro-rocket was to burn out and be jettisoned at an altitude of 11 kilometres above the lunar surface. It is possible that the motor had some kind of a structural fault that caused the solid propellant to explode. For more than 25 years, until Mars Observer was lost in similar circumstances in 1993, Surveyor 4 remained the last US probe to have catastrophically failed in flight.

A depiction of the phases of Surveyor mission to land on the Moon.

A model of the Mariner 9 spacecraft.

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