A model of a liquid metal-cooled reactor, dual 100-kw Brayton Power Conversion is seen on display during an event where NASA is outlining how the agency is executing President Donald J. Trump’s National Space Policy and accelerating preparations for America’s return to the surface of the Moon by 2028, Tuesday, March 24, 2026, at the Mary W. Jackson NASA Headquarters building in Washington. During the event NASA leadership provided updates on mission priorities, including sending the first astronauts to the lunar surface in more than 50 years, establishing the initial elements of a permanent lunar base, getting America underway in space on nuclear propulsion, and other objectives. Photo Credit: (NASA/Bill Ingalls)

Set up of a Brayton Cycle Power System test in the Space Power Facility’s massive vacuum chamber at the National Aeronautics and Space Administration’s (NASA) Plum Brook Station in Sandusky, Ohio. The $28.4-million facility, which began operations in 1969, is the largest high vacuum chamber ever built. The chamber is 100 feet in diameter and 120 feet high. It can produce a vacuum deep enough to simulate the conditions at 300 miles altitude. The Space Power Facility was originally designed to test nuclear-power sources for spacecraft, but it was never used for that purpose. The Space Power Facility was first used to test a 15 to 20-kilowatt Brayton Cycle Power System for space applications. Three different methods of simulating solar heat were employed during the tests. Lewis researchers studied the Brayton power system extensively in the 1960s and 1970s. The Brayton engine converted solar thermal energy into electrical power. The system operated on a closed-loop Brayton thermodynamic cycle with a helium-xenon gas mixture as its working fluid. A space radiator was designed to serve as the system’s waste heat rejecter. The radiator was later installed in the vacuum chamber and tested in a simulated space environment to determine its effect on the power conversion system. The Brayton system was subjected to simulated orbits with 62 minutes of sun and 34 minutes of shade.