The first flight director of US space agency Nasa has died at the age of 95 - days after 50th anniversary celebrations of the first Moon landing.
Chris Kraft, who joined Nasa in 1958, developed the planning and control processes for crewed space missions.
He set up Nasa's Mission Control operations to manage America's first manned space flight and the subsequent Apollo missions to the Moon.
"His legacy is immeasurable," Nasa chief Jim Bridenstine said.
"America has truly lost a national treasure today with the passing of one of Nasa's earliest pioneers," he said in a statement announcing Kraft's passing.
"Chris was one of the core team members that helped our nation put humans in space and on the Moon."
The 1969 Moon landing was marked last Saturday with a series of events by the agency, as well as broadcasters and space enthusiasts around the world.
Kraft was born on 28 February 1924 in Phoebus, Virginia, where he attended school and developed an interest in playing baseball, as well as the drum and bugle.
He enrolled at Virginia Polytechnic Institute (VPI, now Virginia Tech) in 1941 to study mechanical engineering.
The next year, as the US became ever more involved in World War Two, Kraft decided to join the US Navy as an aviation cadet. But injuries to his right hand, sustained when was badly burned at the age of three, meant that he was declared unfit for military service.
Back at VPI, an optional course in basic aerodynamics inspired him to major in aeronautical engineering, the subject in which he graduated in 1944.
He went on to join the federal National Advisory Committee on Aeronautics - Nasa's predecessor - at Langley, a few miles from his home in Virginia. Assigned to the Flight Research Division, he contributed to programmes which included evaluating the flying qualities of aircraft and tests to measure supersonic aerodynamics.
After a stellar career at Nasa in Houston, Texas, he retired in 1982.
But it wasn't the end of his working life: Kraft went on to consult for companies including IBM and Rockwell International, as well as serving as a director of the Houston Chamber of Commerce and as a member of the Board of Visitors at Virginia Tech.
His 2001 autobiography - Flight: My Life in Mission Control - became a New York Times bestseller.
In 2006, Nasa honoured Kraft for his crucial work in America's space programmes with the Ambassador of Exploration Award, given to astronauts and other key individuals who participated in the Mercury, Gemini, and Apollo programmes between 1961 and 1972.
Nasa named its mission control building at the Johnson Space Center in Houston the Christopher C Kraft Jr Mission Control Center, in 2011.
He died in Houston on Monday. No other details of his death have been released.
He leaves a wife, Betty Anne, whom he met at high school and married in 1950, and a son and a daughter.