E-6 n°1, sometimes known in the West as Sputnik 25, was a Soviet spacecraft that was launched in 1963 but was placed into a useless orbit due to a problem with the upper stage of the rocket that launched it. It was a 1,500-kilogram Luna E-6 spacecraft, the first of twelve to be launched. It was intended to be the first spacecraft to perform a soft landing on the Moon, a goal that would eventually be accomplished by the final E-6 spacecraft, Luna 9.

The spacecraft consisted of a cylindrical section containing rockets and fuel for maneuvering, attitude control, and landing, as well as radio transmitters, and a 100-kilogram instrumented probe, which would have been ejected onto the surface after the spacecraft landed, carrying a camera and devices to measure radiation. It was intended to return data on the mechanical characteristics of the lunar surface, the hazards presented by the topology--such as craters, rocks, and other obstructions--and radiation, in preparation for future manned landings.