steel and wood to test facilities for later handling the actual vehicle. Until it was removed for refurbishment in February 2021 it sat atop an external tank with solid rocket boosters attached. The tank and boosters remain. The center showcases significant military rockets, including representatives of the Project Nike series, which formed the first ballistic missile defense, MIM-23 Hawk surface-to-air missile, Hermes, an early surface-to-surface missile, MGR-1 Honest John and Corporal nuclear missiles and Patriot, first used in the Gulf War of 1991. The rocketry collection includes numerous engines, as well. In addition to the authentic engines mounted on rockets on display, the museum has unmounted engines on display, including two F-1s, the type of gigantic engine that produced to push Saturn Vs off the launch pad, J-2 engine that powered second and third stages of the Saturn V, and both Descent and Ascent Propulsion System (DPS/APS) engines for the Lunar Module. Engines from the V-2 engine to NERVA to the Space Shuttle Main Engine are on display as well. The Apollo program gets full coverage in the Davidson Center for Space Exploration with artifacts outlining Apollo missions. Astronauts crossed the service structure's red walkway to the White Room, both on display, and climbed in the Command Module atop a Saturn V which was their cabin for the trip to the Moon and back. The Apollo 16 command module, which orbited the Moon 64 times in 1972, is on display. The Saturn V Instrument Unit controlled five F-1 engines in the first stage of the rocket as it lifted off the pad. Several exhibits relate the complexity and magnitude of that phase of the journey. They took a Lunar Module (mockup on display) to the lunar surface where they collected Moon rocks such as the Apollo 12 specimen at the museum. Later Moon trips took a Lunar Roving Vehicle (displayed beside the LM). The first few Moon trips ended at a Mobile Quarantine Facility (Apollo 12's is on display) where astronauts stayed to ensure containment of any Moon contamination after that mission. A restored engineering mock-up of Skylab is also on display, showing the Apollo project's post-lunar efforts. Various simulators help visitors understand the spaceflight experience. Space Shot lets the rider experience launch-like 4 gs and 2–3 seconds of weightlessness. G-Force Accelerator offers 3 gs of acceleration for an extended period by means of a centrifuge. Several other simulators entertain