Guidance, Navigation, and Control
The functions of guidance, navigation, and control are vital to all forms of air and space flight. The Space History collections in this area attempt to reflect that significance and illustrate the breadth of the topic.
In practice these three functions blend into one another, and artifacts from this collection often perform multiple duties. For this collection, "guidance" shall refer to controlling a vehicle during acceleration or deceleration, mainly during the powered phase of flight, i.e. to align the thrust vector of a rocket or jet engine to coincide with (or deviate slightly from) the vehicle's center of mass, or to use aerodynamic controls such as fins to aim the vehicle properly during its flight. Guided missiles, which are powered for most of their flight, require continuous guidance (hence the name), but in a typical space mission, a rocket burns for only a fraction of the total time of the mission and would require guidance for only that short period of time. Once the rocket engines shut off, there follows the function of "navigation," which is to get from one position in space to another. In contrast to navigation at sea or in the air, space navigation typically consists of long periods of coasting with periodic corrections. Finally, "control" is defined as orienting the space craft in its rotational axes to perform its various operations, such as pointing a telescope, orienting an antenna toward Earth, preparing the vehicle for a rocket burn, etc. Again in contrast to aircraft and ships, in the absence of an atmosphere a spacecraft may be oriented in any direction, but it is usually not desirable to allow it to tumble with no control.
"Control" is also used in another context, namely the management of a mission from the ground (e.g. NASA?s "Mission Control" in Houston). Passenger aircraft fly with periodic communication with air traffic controllers on the ground, but in general they fly with a great deal of autonomy. In contrast, spacecraft that carry a human crew are intensively managed from the ground, where controllers monitor the vehicle?s performance, ensure the safety of the crew, and manage the crew?s schedule and operations. Robotic spacecraft may require less control, but during critical phases of their missions they are also intensively controlled from Earth. The National Air and Space Museum?s collections in this area attempt to show the breadth and depth of this topic by a judicious selection of artifacts.