In the 1930s, gold was discovered there, and the city of Yellowknife was founded. It became the capital of the Northwest Territories. In 1967, an all-season highway was built around the lake, originally an extension of the Mackenzie Highway but now known as Yellowknife Highway or Highway 3. On January 24, 1978, a Soviet Radar Ocean Reconnaissance Satellite, named Kosmos 954 fell from orbit and broke apart. The satellite had an on board nuclear reactor. Pieces of the nuclear core fell near the Great Slave Lake. 90% of the nuclear debris was recovered by a group called Operation Morning Light. They included people from both the United States and Canada.