In 1981, two satellites were launched by NASA to study the interactions between Earth's magnetosphere and ionosphere

In 1981, two satellites were launched by NASA to study the interactions between Earth's magnetosphere and ionosphere. The Dynamics Explorer mission used two spacecraft, DE-1 and DE-2, to study space plasma, electric currents and energy flow. Both satellites launched together and followed polar orbits. DE-1 operated at higher altitudes, while DE-2 studied the region closer to Earth before re-entering the atmosphere in 1983.