Laboratory drop towers for the experimental simulation of dust-aggregate collisions in the early solar system.For the purpose of investigating the evolution of dust aggregates in the early Solar System, we developed two vacuum drop towers in which fragile dust aggregates with sizes up to ~10 cm and porosities up to 70% can be collided.  One of the drop towers is primarily used for very low impact speeds down to below 0.01 m/sec and makes use of a double release mechanism.  In both drop towers, the dust aggregates are in free fall during the collision so that they are weightless and match the conditions in the early Solar System.
drop towers
Collisions are recorded in stereo-view by two high-speed cameras, which fall along the glass vacuum tube in the center-of-mass frame of the two dust aggregates.  Here, two fixed high-speed cameras record the collision events. 
high-speed cameras
The other free-fall tower makes use of an electromagnetic accelerator that is capable of gently accelerating dust aggregates to up to 5 m/sec. 
electromagnetic accelerator