These engineers exclusively work on the design, development, testing, and maintenance of airplanes, spacecrafts, and missiles. They are mostly employed by the government of their respective countries to work on aviation, defense systems, and space expeditions. There are two types of engineers in this sector, aeronautical engineers, who work on airplanes, and astronautical engineers, who work solely on spacecrafts. They are professionals in structural design, instrumentation, and communication of navigations control systems of airplanes and space shuttles. As and when required, they may also be required to work on commercial planes, fighter jets, helicopters, missiles or rockets.