Owl

American earth ionosphere satellite. 2 launches, 1967.05.18 (Transit 16) to 1967.09.25 (Transit 17).

Originally to be part of the Explorer series, but instead orbited under the auspices of the US Army, Owl was designed to investigate a variety of low and high latitude phenomena and to make particularly powerful studies of auroral phenomena. Rice University built 2 spacecraft, scheduled for late 1968 launch by Scout boosters. The satellites were put into similar but not identical orbits at a high inclination with nominal altitudes of 930 and 1100 km and with coincident but anti-parallel lines of nodes. The two flight units (Rice also built a flight-worthy spare and prototypes of selected subsystems) were identical except that a large permanent magnet was in opposite directions. Each satellite had a flight mass of about 70 kg; cylindrical, it had a height of 0.84 m and a diameter of about 0.76 m. Power was obtained by 8.000 solar cells distributed on all sides.