Cosmos 1001 is a code name for the first unmanned test flight of the Soviet Soyuz spacecraft 7K- ST. It was common in the Soviet Union to give only successful missions an official name. Failed flights were mostly not announced and test flights only under the general cover name cosmos.
This was the first test flight of a new spacecraft Soyuz 7K- type ST ( Soyuz -T), which should serve as a feeder vessel for the Salyut stations. It was based on the type Soyuz 7K -S, which was intended for autonomous military flights, but was never used. After three rail maneuvers the spacecraft occurred on April 15th 1978 back into the Earth's atmosphere. The flight was considered a failure.