But before Discovery could go on display, some hazardous materials had to be removed. As Valerie Neal, a curator in the Museum’s space history division, says, some of those materials included propellant residues in the orbital maneuvering system, reaction control systems, and auxiliary power units. Also discarded were the explosive charges found throughout the shuttle, including in the landing gear, side hatch, and drag chute system.
Some items, like the main engines, were removed but remain with NASA, for possible use on other projects. Other items, like the shuttle’s galley, were reinstalled in order to keep Discovery as close to its flown condition as possible.
Every artifact in the National Air and Space Museum is the real thing, though some real things, like the Hubble Test Telescope, are test vehicles instead of flight hardware. If there is any doubt, the labels in the galleries will tell all.