Molniya Orbit

The Molniya orbit is a specific type of highly elliptical orbit designed by the Soviet Union in the 1960s for communications coverage over Arctic and Siberian regions. With a 12 hour period, 500 km perigee, and 40,000 km apogee at 63.4° inclination, the satellite spends roughly 8 of every 12 hours near apogee over the northern hemisphere — appearing nearly stationary to ground observers there. The 63.4° inclination is critical: at this "critical inclination," the argument of perigee does not precess, keeping apogee locked over the desired hemisphere. A constellation of three Molniya satellites provides continuous northern coverage.