Surveyor Lunar Spacecraft

Surveyor 3 on moon, taken by Apollo 12 astronauts - NASA photo

Built for NASA by Hughes Aircraft Co., the Surveyors were robotic spacecraft used as pathfinders for subsequent landings of humans on the moon. During 1966 and 1967, five made successful landings in support of the Apollo program.

Surveyor 1 was launched to the moon four months after Luna 9 on a direct-ascent trajectory. It was powered by three liquid-propellant variable-thrust engines and one solid propellant main engine. It proceeded to a near-hover at 13 feet and then made a free fall to a landing. Shock-absorber legs and crushable pads on the frame softened the blow of the impact. For the next six weeks, including a two-week-long shutdown for the lunar night, Surveyor 1 transmitted 11,237 pictures back to Earth, all in high resolution and color.

Surveyor 2 was lost because an engine failed to fire. Surveyor 3 bounced twice but managed to send back 6,300 pictures. Many of these were of its mechanical scoop used to dig 7 inches into the lunar soil. Observations and readings indicated that the soil was similar to wet beach sand and could support a human and a lander vehicle. Apollo 12 later landed within a quarter mile of Surveyor 3, and astronauts retrieved parts of it to determine the effects of long exposure to the lunar environment.

Surveyor 4 was lost after transmissions ceased. Surveyor 5 carried a material that irradiated the soil so that its composition could be analyzed. Surveyor 6 hopped 8 feet away from its landing site for more pictures. Surveyor 7 was sent to the rim of the lunar crater Tycho and transmitted more that 21,000 pictures, including images of two laser beams from stations on Earth.

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Specifications
First launch: May 30, 1966
Classification: Robotic spacecraft
Height: 10 feet
Width: 14 feet 1 inches
Weight: 2,283 pounds on Earth, 625 pounds on moon