Each of the six manned Apollo missions that put down on the moon's surface planted an American flag in the lunar soil. The one flag not still upright is the one planted during the first moon landing by the crew of Apollo 11, NASA officials said.
Lunar Reconnaissance Orbiter Camera images were taken of each Apollo site, they said.
"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," LROC principal investigator Mark Robinson wrote in a blog post. 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!"
Researchers examining photos taken of the same spots at Apollo site at various times in the day observed shadows circling the point where the flags were thought to be.
"Intuitively, experts mostly think it highly unlikely the Apollo flags could have endured the 42 years of exposure to vacuum, about 500 temperature swings from 242 F during the day to -280 F during the night, micrometeorites, radiation and ultraviolet light, some thinking the flags have all but disintegrated under such an assault of the environment," James Fincannon, of the NASA Glenn Research Center in Cleveland, wrote in the Apollo Lunar Surface Journal.
Robinson, however, called the photos "convincing."
"Personally I was a bit surprised that the flags survived the harsh ultraviolet light and temperatures of the lunar surface, but they did," Robinson wrote. "What they look like is another question (badly faded?)."