The term microgravity means extremely low or zero gravity conditions. Ever since mankind evolved on this planet our gravity has been a condition of existence. The only individuals who ever experienced microgravity, albeit briefly, were those who fell from high places. Since the advent of space travel, however, microgravity has become an increasingly important area of research for many reasons.

Microgravity conditions can be achieved in several ways. As already mentioned, the condition of free fall will briefly give a zero gravity condition for the duration of the fall. Scientists use drop towers and shafts of varying heights to produce these conditions. At the Lewis Research Center in Cleveland, Ohio there are two facilities (a tower 75 ft tall and a shaft 400 ft deep) which allow experiments of 2.2 and 5.2 seconds respectively.

Another method of achieving microgravity is to push an aircraft through a parabolic arc. The aircraft climbs up...