The Great Dyke, seen from space. View of the Great Dyke, a volcanic intrusion in Zimbabwe, seen from Shuttle Endeavour during Mission STS-54. The Great Dyke is about 500 kilometres in length and averages 10 kilometres in width, and cuts across most of the country. It is thought to be about 2.55 billion years old, and was created when molten lava filled and widened a fracture in the Earth's crust. Mission STS-54 flew on 13-19 January 1993, with the primary task of deploying NASA's TDRS-6 communications satellite.