Editing Luna 18 (section)

==Overview==
''Luna 18'' was placed in an Earth parking orbit after it was launched and was then sent towards the Moon. On 7 September 1971, it entered lunar orbit. The spacecraft completed 85 communications sessions and 54 lunar orbits before it was sent towards the [[lunar surface]] by use of [[braking rocket]]s. It impacted the Moon on 11 September 1971, at 3 degrees 34 minutes N, 56 degrees 30 minutes E (selenographic coordinates) in rugged mountainous terrain. Signals ceased at the moment of impact.

This mission was the seventh Soviet attempt to [[Sample return mission|recover soil samples]] from the surface of the Moon and the first after the success of ''Luna 16''. After two mid-course corrections on 4 September and 6 September 1971, ''Luna 18'' entered a circular orbit around the Moon on 7 September at 100 kilometers altitude with an inclination of 35°. After several more orbital corrections, on 11 September, the vehicle began its descent to the lunar surface. Contact with the spacecraft was lost at 07:48 UT at the previously determined point of lunar landing. Impact coordinates were 3°34' north latitude and 56°30' east longitude, near the edge of the [[Mare Fecunditatis]] ("Sea of Fertility"). Officially, the Soviets announced that "the lunar landing in the complex mountainous conditions proved to be unfavorable." Later, in 1975, the Soviets published data from ''Luna 18''{{'}}s continuous-wave radio altimeter that determined the mean [[density]] of the [[lunar soil|lunar topsoil]].