In physics and materials science, a drop tower or drop tube is a structure used to produce a controlled period of weightlessness for an object under study. Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. Materials Science or Materials Engineering is an interdisciplinary field involving the properties of matter and its applications to various areas of Science and Weightlessness is a phenomenon experienced by people during Free-fall. Air bags, polystyrene pellets, and magnetic or mechanical brakes are sometimes used to arrest the fall of the experimental payload. Cargo (or freight) refers to goods or produce transported generally for Commercial gain by ship, aircraft, train, In other cases, high-speed impact with a substrate at the bottom of the tower is an intentional part of the experimental protocol.

Typical operation

A view down the tube of NASA Glenn's 5 second Zero Gravity Facility. NASA John H Glenn Research Center at Lewis Field (see History for previous names is a NASA center located within the cities of Brook Park

A view down the shaft of NASA Glenn's 2. NASA John H Glenn Research Center at Lewis Field (see History for previous names is a NASA center located within the cities of Brook Park 2 second drop tower. A large (deflated) air bag is at the bottom.

For a typical materials science experiment, a sample of the material under study is loaded into the top of the drop tube, which is backfilled with inert gas or evacuated to create a low-pressure environment. "Inert gases" is also used in a narrower sense for Noble gases An inert gas is any Gas that is not reactive with elements Following any desired preprocessing (e. g. induction heating to melt a metal alloy), the sample is released to fall to the bottom of the tube. Induction heating is the process of Heating an electrically conducting object (usually a Metal) by Electromagnetic induction, where Eddy currents The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across An alloy is a Solid solution or Homogeneous mixture of two or more elements, at least one of which is a Metal, which itself has During its flight or upon impact the sample can be characterized with instruments such as cameras and pyrometers. A camera is a device used to capture images either as still Photographs or as sequences of moving images ( Movies or Videos. Pyrometer is any non-contacting device that intercepts and measures Thermal radiation.

Drop towers are also commonly used in combustion research. Combustion or burning is a complex sequence of Exothermic chemical reactions between a Fuel and an Oxidant accompanied by the production of For this work, oxygen must be present and the payload may be enclosed in a drag shield to isolate it from high-speed "wind" as the apparatus accelerates toward the bottom of the tower. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the See a video of a microgravity combustion experiment in the NASA Glenn 5 s drop facility at [1].

Fluid physics experiments and development and testing of space-based hardware can also be conducted using a drop tower. FLUID ( F ast L ight '''U'''ser '''I'''nterface D esigner is a graphical editor that is used to produce FLTK Source code Sometimes, the ground-based research performed with a drop tower serves as a prelude to more ambitious, in-flight investigation; much longer periods of weightlessness can be achieved with parabolic-flight-path aircraft or with space-based laboratories aboard the Space Shuttle or the International Space Station. In Mathematics, the parabola (pəˈræbələ from the Greek παραβολή) is a Conic section, the intersection of a right circular Vomit Comet is a nickname for any Airplane that briefly provides a nearly weightless environment in which to train Astronauts conduct research and NASA 's Space Shuttle, officially called the Space Transportation System ( STS) is the Spacecraft currently used by the United States

The duration of free-fall produced in a drop tube depends on the length of the tube and its degree of internal evacuation. Free fall is motion with no Acceleration other than that provided by Gravity. The 105-meter drop tube at Marshall Space Flight Center produces 4. George C Marshall Space Flight Center (MSFC the original home of NASA, is a lead center for propulsion, Space Shuttle propulsion Shuttle external fuel 6 seconds of weightlessness when it is fully evacuated. In the drop facility Fallturm Bremen University of Bremen in Bremen, a catapult can be used to throw the experiment upwards to prolong the weightlessness from 4. Fallturm Bremen is a Drop tower at the Center of Applied Space Technology and Microgravity at the University of Bremen in Bremen. The University of Bremen ( German Universität Bremen) is a university of approximately 23500 people from 126 countries that are studying teaching researching and Bremen (ˈbʁeːmən is a Hanseatic city in northwestern Germany (official name Stadtgemeinde Bremen / City Municipality of Bremen A catapult is any one of a number of non-handheld mechanical devices used to throw a Projectile a great distance without the aid of an explosive substance—particularly various 74 to nearly 10 seconds. Neglecting the physical space needed for the initial acceleration, this technique doubles the effective period of weightlessness. The NASA Glenn Research Center has a 5 second drop tower (The Zero Gravity Facility) and a 2. 2 second drop tower (The 2. 2 Second Drop Tower).

Much of the operating cost of a drop tower is due to the need for evacuation of the drop tube, to eliminate the effect of aerodynamic drag. This vacuum means "absence of matter" or "an empty area or space" for the cleaning appliance see Vacuum cleaner. This may be avoided by dropping the experiment placed inside an outer box (the drag shield) in such a way that the experiment can fall relative to the outer box.

Historical uses

Though the story may be apocryphal, Galileo is popularly thought to have used the Leaning Tower of Pisa as a drop tower to demonstrate that falling bodies accelerate at the same constant rate regardless of their mass. Galileo Galilei (15 February 1564 &ndash 8 January 1642 was a Tuscan ( Italian) Physicist, Mathematician, Astronomer, and Philosopher The Leaning Tower of Pisa (Torre pendente di Pisa or simply The Tower of Pisa (it La Torre di Pisa is the Campanile, or freestanding bell tower of the

Drop towers called shot towers were once useful for making lead shot. A shot tower is a Tower designed for the production of shot balls by freefall of molten lead which is then caught in a water basin Lead shot is a collective term for small balls of Lead. It is used primarily as Projectiles in Shotguns but is also used for a variety of other purposes A short period of weightlessness allows molten lead to solidify into a perfect sphere by the time it reaches the floor of the tower. Melting is a process that results in the phase change of a substance from a Solid to a Liquid. Characteristics Lead has a dull luster and is a dense, Ductile, very soft highly

List of drop towers

• NASA Glenn Research Center 2.2 Second Drop Tower
• NASA Glenn Research Center Zero-G Research Facility
• Micro-Gravity Laboratory of Japan (MGLAB)
• Fallturm Bremen
• NASA Marshall Space Flight Center Drop Tube Facility
• Experimental drop tube of the metallurgy department of Grenoble

See also

• Glenn Research Center
• Marshall Space Flight Center
• Magnetic levitation
• Shot tower
• Weightlessness