The Nimbus 7 research-and-development satellite served as a stabilised, earth-oriented platform for the testing of advanced systems used to sense and collect data in the pollution, oceanographic, and meteorological disciplines. The polar-orbiting spacecraft consisted of three major structures: (1) a hollow torus-shaped sensor mount, (2) solar paddles, and (3) a control housing unit that was connected to the sensor mount by a tripod truss structure. These structures gave the spacecraft a configuration somewhat like that of an ocean buoy.