Operations and Checkout Building

The Neil Armstrong Operations and Checkout Building (previously known as the Manned Spacecraft Operations Building) is a historic site on Merritt Island, Florida, United States. The five-story structure is in the Industrial Area of NASA's Kennedy Space Center. Its facilities include the crew quarters for astronauts prior to their flights. On January 21, 2000, it was added to the U.S. National Register of Historic Places.

Apollo program
When it was originally built in 1964 to process spacecraft in the Gemini and Apollo era, it was known as the Manned Spacecraft Operations Building. It was renamed the Operations and Checkout Building during the Apollo program, known informally as the O&C.

Altitude test chambers
In 1965, a pair of altitude chambers were installed in the High Bay for testing the environmental and life support systems of both the Apollo Command/Service Module and Lunar Module at simulated altitudes of up to 250,000 ft. Each chamber is 58 ft high (with a clear working height of 28 ft) and an interior diameter of 33 ft, were human-rated, and capable of reaching the maximum altitude (minimum pressure) in one hour. These were used by the prime and backup crews of all manned missions, from the ill-fated Apollo 1 in October 1966, through to the Apollo-Soyuz Test Project in July 1975.

Post-Apollo use
During the 1980s and 90s the O&C building was used to house and test Spacelab science modules before their flights aboard the Space Shuttle.

In the 2000s, trusses for the International Space Station were checked out in the building.

On January 30, 2007, NASA held a ceremony to mark the transition of the building's high bay for use by the Constellation program. The building would serve as the final assembly facility for the Orion crew exploration vehicle. In preparation for the transition, the state of Florida provided funds to clear the facility of about 50 ST of steel stands, structures and equipment. Renovations totaling $55 million took place from June 2007 through January 2009, at which point Lockheed Martin became the operator of the facility for Orion production.