The United States Navy (USN) mounted several expeditions to Antarctica in the period 1946 to 1959. These expeditions (Operation Highjump led by R. E. Byrd, Windmill, and Deep Freeze I–IV) included aerial photography using the Trimetrogon system of aerial photographs (TMA; vertical, left, and right oblique images over the same point) over portions of coastal Marie Byrd Land.[11]