Surveyor 5

Surveyor 5 landed in Mare Tranquillitatis on September 11, 1967 after engineers overcame a helium leak in its propulsion pressurization system. It became NASA's third successful Surveyor landing and carried an alpha-scattering instrument in place of the earlier surface sampler, together with a television camera and a magnet on a landing footpad. The instrument measured the relative abundance of chemical elements directly on the Moon, supporting a basaltic interpretation of the local material. Images and magnetic observations added context for the surface analysis. A brief engine firing tested how exhaust disturbed the soil, and the spacecraft ultimately transmitted more than 20,000 pictures across several lunar days before contact ended in December 1967.