Travel beyond the earth's atmosphere.

Condition in which no acceleration, whether due to gravity or any other force, can be detected by an observer within a system. It also means the absence of weight or the absence of the force of gravity acting on a body. Microgravity, gravitational force between 0 and 10 -6 g, is included here. (From NASA Thesaurus, 1988)

The use of wings or wing-like appendages to remain aloft and move through the air.

That branch of medicine dealing with the studies and effects of flight through the atmosphere or in space upon the human body and with the prevention or cure of physiological or psychological malfunctions arising from these effects. (from NASA Thesaurus)

In a medical context, the term "wing" is not typically used as a standalone definition; however, it can refer to various flat, wing-shaped structures in anatomy, such as the iliac wings of the pelvis or the zygomatic wings of the cheekbone.

A weight-carrying structure for navigation of the air that is supported either by its own buoyancy or by the dynamic action of the air against its surfaces. (Webster, 1973)

Members of spacecraft crew including those who travel in space, and those in training for space flight. (From Webster, 10th ed; Jane's Aerospace Dictionary, 3d ed)

Design, development, manufacture, and operation of heavier-than-air AIRCRAFT.

The motion of air relative to the earth's surface.