Drop Tower
Drop towers are multi-purpose facilities, which enable autonomous experiment packages to be submitted to true free-fall conditions. ESA works with the ZARM drop tower, which is a 146m tall concrete tower housing an evacuated metal tube, which can provide microgravity up to three times a day for experiments dropped from the top of the tower (4.74 seconds of microgravity) or catapulted upwards from below the tower (9.3 seconds).
A series of experiments can be conducted over repeated drops, enabling scientists to screen ranges and parameters. Drop towers are very useful for obtaining quantitative data on physical phenomena with short characteristic times in the absence of gravity-driven disturbances.
Through a Continuously Open Research Announcement for the ZARM Drop Tower in Bremen, Germany (more info here), ESA provides scientists with an opportunity to conduct research necessary to advance knowledge relevant to the effects of space in the areas of Life and Physical Sciences, with the overarching aim of contributing to safe and sustainable space exploration with human crews.