The Free Fall Tower (in German fallturm) located in the city of Bremen, Germany, is the only one of its kind in Europe, designed to study and experiment the effects of weightlessness (actually microgravity, since G forces are not absolutely zero, although it is used as a synonym ).
The use of towers for this purpose goes back, according to unconfirmed history, to Galileo, who would have used the Tower of Pisa to show that two falling bodies accelerate at the same constant speed, regardless of their mass.
In the world there are other similar facilities, some underground such as NASA’s Zero Gravity Research Facility in Cleveland, which reaches 160 meters underground. The oldest is the pagoda of the Royal Botanical Gardens of Kew, in the United Kingdom, built in 1762 and whose 50-meter height was used in World War II to perfect the design of aerial bombs, throwing them through open holes on each floor of the building.
The Bremen tower is part of the Center for Applied Astronautics and Microgravitation (ZARM) of the local university. Its silhouette stands out above the urban skyline since its construction in 1990 with its 146-meter height and its cylindrical concrete and steel structure, topped by a conical point, which gives it a futuristic look. There, up to three weightlessness experiments are carried out daily (more than 400 per year in different fields: astrophysics, biology, chemistry, fluid dynamics, physics, etc.). And tests of materials and equipment for space missions are carried out.
The inner tube is 122 meters high. Through it, a capsule containing the object or product of study is launched, which initially falls, reaching a state of weightlessness for 4.74 seconds.
But after its construction, a compressed air catapult was installed about 12 meters below the level of the tower. Using this catapult, weightlessness is extended to 9 seconds.
As it falls, the capsule hits an 8-meter-tall container filled with pinhead-sized expanded polystyrene balls. For each experiment, a vacuum must be made inside the inner tube until reaching 10-4 bar.
Around the tower is the control building, which allows visits and even organizes guided tours and experiments to explain microgravity. It also accepts external experiments, and is apparently one of the cheapest labs for that purpose.
ZARM-University of Bremen / Wikipedia.