Introduction: Surveyor 5 science results

Surveyor 5 landed in Mare Tranquillitatis. The spacecraft and its operation are briefly described in this paper. An α-particle backscattering instrument abroad Surveyor 5 provided the first on-surface measurements of the elemental composition of the lunar surface, and a magnet indicated the amount of material with high magnetic susceptibility. Strain-gage measurements during the landing and during a rocket engine firing against the surface, in conjunction with television pictures of the disturbances produced, furnished information on mechanical properties and particle-size distribution of the surface material. Thermal sensors, radar systems, and radio Doppler measurements provided data on other local properties and on lunar motion; the spacecraft took 19,118 television pictures of lunar features, solar corona, and sky.