During each of the six American Moon landings, astronauts left American flags behind as symbols of their nation's scientific and engineering achievement.
The first was the monumental Jul 20, 1969, Apollo 11 landing in which Armstrong declared on live television, "one small step for man, one giant leap for mankind".
The final mission was Apollo 17 on Dec 14, 1972.
Scientists used new, detailed images from NASA's Reconnaissance Orbiter Camera (LROC) to determine that the flags were casting shadows that circled them as the Moon moved in its normal orbit proving that they were still standing on their poles.
"From the LROC images it is now certain that the American flags are still standing and casting shadows at all of the sites, except Apollo 11," Mark Robinson, an investigator with the lunar satellite programme wrote.
"Astronaut Buzz Aldrin reported that the flag was blown over by the exhaust from the ascent engine during liftoff of Apollo 11, and it looks like he was correct!" Robinson wrote. The American missions to the Moon remain the only manned flights to touch down on a heavenly body.
"Personally I was a bit surprised that the flags survived the harsh ultraviolet light and temperatures of the lunar surface, but they did," he wrote.
"What they look like is another question," Robinson wrote. The conditions on the surface of the Moon are harsh. Temperatures swing between 250 and -280 degrees Fahrenheit, the report said.