The Spacecraft Propulsion Research Facility (commonly known as the B-2 facility), located at NASA's Neil A. Armstrong Test Facility (formerly Plum Brook Station) near Sandusky in Erie County, Ohio, is historically significant as the world's only facility capable of testing full-scale upper-stage launch vehicles and rocket engines under fully simulated space conditions. Constructed between 1962 and 1969, the facility features an immense stainless-steel vacuum chamber measuring 38 feet in diameter and 55 feet deep, housed within a 120-foot-tall concrete containment building. This unique engineering marvel allowed scientists to subject live-firing rocket engines to the extreme cold (-320F), high vacuum, and thermal radiation of deep space, ensuring that critical propulsion systems would perform reliably after leaving Earth's atmosphere.

Designated a National Historic Landmark in 1985 as part of the "Man in Space" thematic initiative, the facility played a pivotal role in the advancement of the United States space program. It was instrumental in the development and qualification of the liquid-hydrogen-fueled Centaur upper-stage rocket, which powered iconic robotic exploration missions including the Surveyor lunar landers, the Viking Mars landers, and the Pioneer and Voyager deep-space probes. By enabling safe, ground-based testing of complex, high-energy propulsion systems prior to flight, the Spacecraft Propulsion Research Facility made indispensable contributions to America's journey to the Moon and the subsequent exploration of the solar system.