Drop tower - a facility used for achieving microgravity by dropping (or in some cases tossing) an experiment. Drop shafts are usually evacuated. Drop tubes usually don't have an experiment container.
Project Persephone will require some way to validate its designs for telebots, inflatable space structures, and perhaps other mechanisms in orbiting exovivaria, under the most realistic conditions possible on Earth. At certain scales, and for operations not requiring too much time, drop tower experiments might suffice, especially if there is some way to brace the units under test as they are rapidly decelerated, so that testing is non-destructive. With appropriate bracing and sequencing, it might be possible to manually practice some kinds of telebotic operations, and study the behavior of some kinds of automated equipment, over several drop tower runs.
Drop towers equipped with catapults, such as FallTurm Bremen, can provide over 9 seconds of microgravity. Drop shafts drilled deep into the ground, such as JAMIC1 2, have provided up to 10 seconds. At up to 3 experiments per day3, it might be possible to perform about half a minute worth of microgravity tests and exercises per day, at the high-end facilities. There are other, shorter-duration facilities available in Australia4, in the U.S.5 6 7 (including a 1-second drop for assessing fuel slosh in scale models of spin-stabilized craft8), France9 and Japan.10
1 JAMIC drop shaft, Kami-sunagawa, Hokkaido http://microgravity.com/tutorial-obtaining-page2.html ⇑
2 "Research under Microgravity Environment" Hokkaido National Industrial Research Institute http://www.hniri.go.jp/chap2/gra-st-e.html ⇑
3 "Catapult Details - Bremen Drop Tower", ZARM Center of Applied Space Technology and Microgravity ⇑
4 QUT microgravity facility, Brisbane http://www.bee.qut.edu.au/research/projects/microgravity/facility.jsp ⇑
5 2.2 second drop tower, NASA Glenn Research Center, Cleveland OH http://facilities.grc.nasa.gov/drop/ ⇑
6 Zero Gravity Research Facility (5 sec drop), NASA Glenn Research Center, Cleveland OH http://facilities.grc.nasa.gov/zerog/ ⇑
7 Marshall Space Flight Center Dynamic Test Stand Drop Tube Facility - reportedly mothballed, narrow (26 cm) diameter, no container, destructive testing only http://science.nasa.gov/ssl/msad/dtf/tube.htm ⇑
8 Applied Dynamics Laboratory, Portland OR http://www.fuelslosh.com/ADL/DROP_TEST.html ⇑
9 CERUM - Département d'études des Matériaux, Grenoble - drop tube, containerless, presumably destructive, metallurgical orientation http://conferences.esa.int/00a06/abstracts/206.html ⇑
10 Micro-Gravity Laboratory of Japan (MGLAB),Kawai, Izumi-cho, Toki City, Gifu Pref http://www.mglab.co.jp/index_e.html ⇑
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