モルニヤ軌道
A Molniya orbit (, "Lightning") is a type of satellite orbit designed to provide communications and remote sensing coverage over high latitudes. It is a highly elliptical orbit with an inclination of 63.4 degrees, an argument of perigee of 270 degrees, and an orbital period of approximately half a sidereal day. The name comes from the "Molniya" satellites, a series of Soviet/Russian civilian and military communications satellites which have used this type of orbit since the mid-1960s.