Astronautics is that area of engineering and technology which is concerned with spaceflight. The discipline encompasses several technical fields, including
astrodynamics, propulsion, structures, power supplies, thermal control, and communications. Astrodynamics, the study of
spacecraft motion through force fields in space, is the cornerstone of
Astronautics.A distinction is made between celestial mechanics and astrodynamics. The former is associated with the natural motion of celestial bodies; the latter refers to the controlled motion of spacecraft. Astronautics may essentially be said to have its origins in the theoretical works of Konstantin Tsiolkovsky at the start of the 20th century (see space exploration). The knowledge of celestial mechanics preceded the development of astrodynamics by several hundred years.Basic differences also exist between astronautics and aeronautics, the flight of spacecraft as opposed to that of aircraft. An airplane uses aerodynamic forces (those resulting from the action and reaction associated with air movement) for its flight and the control of flight. The pilot implements this control through devices that change the
orientation of deflecting surfaces about the craft. He or she can use visual and instrument cues for knowing when to make altitude and flight-path corrections. An
Astronaut uses propulsive or internally caused torques to control orientation. Having no horizon or magnetic compass, the astronaut relies on gyroscopes and special sensors to make changes in attitude. A spacecraft flies because of a balance between gravitational and centrifugal forces.