Surveyor program

The missions called for the craft to travel directly to the Moon on an impact trajectory, a journey that lasted 63 to 65 hours, and ended with a deceleration of just over three minutes to a soft landing.

Several Surveyor spacecraft had robotic shovels designed to test lunar soil mechanics.

Some of the Surveyors also had alpha scattering instruments and magnets, which helped determine the chemical composition of the soil.

The simple and reliable mission architecture was a pragmatic approach to solving the most critical space engineering challenges of the time, namely the closed-loop terminal descent guidance and control system, throttleable engines, and the radar systems required for determining the lander's altitude and velocity.

The Surveyor missions were the first time that NASA tested such systems in the challenging thermal and radiation environment near the Moon.

Each Surveyor mission consisted of a single unmanned spacecraft designed and built by Hughes Aircraft Company.

The remainder of the trip to the surface, lasting about 2.5 minutes, was handled by smaller doppler radar units and three vernier engines running on liquid fuels fed to them using pressurized helium.

The last 3.4 meters to the surface was accomplished in free fall from zero velocity at that height, after the vernier engines were turned off.

The spacecraft returned data on the motion of the Moon, which would be used to refine the map of its orbital path around the Earth as well as better determine the distance between the two worlds.

The Apollo 12 astronauts excised several components of Surveyor 3, including the television camera, and returned them to Earth for study.

[8] Launched on July 14, 1967, Surveyor 4 crashed after an otherwise flawless mission; telemetry contact was lost 2.5 minutes before touchdown.

[9] The planned landing target was Sinus Medii (Central Bay) at 0.4° north latitude and 1.33° west longitude.

The successful completion of this mission satisfied the Surveyor program's obligation to the Apollo project.

After moving west eight feet, (2.5 m) the spacecraft once again successfully soft landed and continued functioning as designed.

On January 20, while the craft was still in daylight, the TV camera clearly saw two laser beams aimed at it from the night side of the crescent Earth, one from Kitt Peak National Observatory, Tucson, Arizona, and the other at Table Mountain at Wrightwood, California.

During the time of the Surveyor missions, the United States was actively involved in the Space Race with the Soviet Union.

Atlas-Centaur injecting a Surveyor lander directly into trans-lunar flightpath
Image from Surveyor 1 of its footpad in order to study soil mechanics in preparation for the Apollo crewed landings.
Astronaut Pete Conrad near Surveyor 3 during Apollo 12, 1969. Lunar Module in the background.
Lunar surface imaged by Surveyor 5
Surveyor 6 effects of the vernier-rocket engine blast on the double imprint previously made in the lunar surface by one of the spacecraft's crushable blocks during the initial touchdown
Photomosaic of lunar panorama near the Tycho crater taken by Surveyor 7. The hills on the center horizon are about eight miles away from the spacecraft.
Surveyor-Model 1: A 952 kg mass representative for the Surveyor lunar probe. The cylindrical mass was permanently connected to the Centaur upper stage.
Surveyor-SD 2. Simulated Surveyor payload with the same dynamic properties as the real probe.
An engineering model of Surveyor 3, S-10, used for thermal control tests. It was reconfigured to represent a flight model of Surveyor 3 or later, since it was the first to have a scoop and claw surface sampler. (National Air and Space Museum)