The spacecraft was launched on June 3 , 1974 into a polar orbit with initial apogee over the North Pole .
The spacecraft was re-entered on April 28 , 1978 after 667 orbits or nearly four years of continuous operation .
The spacecraft was launched on June 3 , 1974 into a polar orbit with initial apogee over the North Pole and re-entered on April 28 , 1978 after 667 orbits or nearly four years of continuous operation .