Eric Newman gave the Academites a tour of the 5.18s drop facility at Glenn Research Center on July 21st. The drop tower was constructed in 1966 and is now a national historic landmark. The tower extends 509 feet below ground level and, with over 5000 drops to date, it is the largest in the world. The 28 ft. diameter concrete cylinder takes 1 hour to evacuate the chamber, creating a vacuum with 0.1 torr of pressure.
In order to perform a drop, the experiment is fitted into one of seven 2,500 lb drop vehicles. The vehicle is loaded to the top of the drop tower, where the tower is then evacuated prior to breaking the bolt. The payload plummets 432 ft, reaching 113 mph, and stops in 150 ms in 12 ft of expanded polystyrene pellets, experiencing 35 Gs and a peak of 65 Gs.
The drop tower also has the ability to mimic partial gravitational fields, such as lunar or Martian gravity. In these cases, the experiment rotates within the drop vehicle at a precise velocity. The angular velocity causes it to experience a partial force. The magnitude of the simulated gravity is defined by the proximity of the experiment to the center of rotation. Therefore, this method of partial gravity attainment limits the available space for the experiment.