Forty Years of Radio Astronomy at Hartebeesthoek

In 1961 an 85-foot (26-metre) diameter radio antenna was erected at Hartebeesthoek near Johannesburg, as NASA's Deep Space Instrumentation Facility 51. A young South African engineer employed there soon initiated a radio astronomy research programme to use free time between tracking spacecraft. On the closure of the facility by NASA in 1974, it was re-constituted as a radio astronomy observatory operated by the CSIR. In this paper, we highlight various strands of the forty year history of radio astronomy at Hartebeesthoek. We also cover some of the perhaps surprising spinoffs that it has generated, both scientifically and practically. Some of these hark back to measurements taken by the Abbé de la Caille at the Cape in the 1750's, and to the reasons for establishing a Royal Observatory there in the 1820's.