Drop Towers can be used to experience brief periods of absence of weight: these drop towers consist of high tubes, or towers, or deep wells into which specially designed experiment modules are dropped. The time in which the absence of weight is experienced is no more than few seconds and depends on the height from which the module is launched. In order to limit air drag, the experiments are conducted in a vacuum or in conditions of reduced gas pressure. These experiments are much cheaper than those conducted in flight and are sometimes preliminary tests for flight experiments.
Fallturm Bremen at the University of Bremen.
123-meter-high (actual drop distance 110 m), for 4.74 seconds (with release of the drop capsule), or for over 9 seconds (with the use of a catapult) weightlessness conditions.
Zero Gravity Facility John H. Glenn Research Center at Lewis Field
Tunnel view looking up from level 5.
This tower drops 460 feet and allows scientists 5.18 seconds of zero gravity.