The photos have stood the test of time: A spacesuit-clad Apollo astronaut stands proudly next to a red-white-and-blue American flag, his national trophy telling the lonely world "the United States was here".
Unfortunately, all six flags they planted from 1969 through 1972 haven't fared so well.
Images taken by NASA's Lunar Reconnaissance Orbiter in 2012 do show that at least five out six flags still stand. However, scientists think decades' worth of brilliant sunlight have bleached out their emblematic colours.
The result? The flags are probably completely bone-white by now, as we first learned from Gizmodo. But their condition may be even worse than that.
Each one of the flags was made by the company Annin Flagmakers, woven out of rayon, and cost NASA US$5.50 (more than US$32.00 when adjusted for inflation).
On the surface of Earth, such flags fade in sunlight. That's because ultraviolet light - the same wavelength that causes sunburn - isn't fully absorbed by our planet's atmosphere, and it excels at breaking down fibres and colours.
The Moon doesn't have any atmosphere to absorb sunlight, and outside of craters there is no shade.
This means the flags planted by the Apollo astronauts are exposed to constant, gleaming sunlight and even more solar radiation, and for two-week stretches at a time. (One 'day' on the Moon lasts about 28 Earth days.)
Writing in a July 2011 article for Smithsonian Air&Space magazine, lunar scientist Paul Spudis explains:
"Over the course of the Apollo program, our astronauts deployed six American flags on the Moon. For forty-odd years, the flags have been exposed to the full fury of the Moon's environment - alternating 14 days of searing sunlight and 100°C heat with 14 days of numbing-cold -150°C darkness.
But even more damaging is the intense ultraviolet (UV) radiation from the pure unfiltered sunlight on the cloth (modal) from which the Apollo flags were made. Even on Earth, the colours of a cloth flag flown in bright sunlight for many years will eventually fade and need to be replaced.
So it is likely that these symbols of American achievement have been rendered blank, bleached white by the UV radiation of unfiltered sunlight on the lunar surface. Some of them may even have begun to physically disintegrate under the intense flux.
America is left with no discernible space program while the Moon above us no longer flies a visible U.S. flag. How ironic."
Will we return to the Moon?
A lot has and has not changed since Spudis' lament nearly six years ago.
NASA is working hard to fly astronauts into deep space, but has since decided to skip a Moon landing using its ultra-powerful Space Launch System rockets. Instead, the space agency plans to send astronauts to Mars by 2033.
There may be hope for a Moon mission in the commercial sector, though.
Amazon.com founder Jeff Bezos, who owns the rocket company Blue Origin, is eager to colonise the Moon.
Should neither company get people to the lunar surface, five teams competing for the US$20 million Google Lunar XPRIZE competition might, as soon as the end of 2017. Their mission includes landing a robot on the surface and broadcasting high-definition footage.
A US $4 million 'Apollo Heritage Bonus Prize' will go to whichever team can record the first live-video stream or panoramic image from the site of Apollo 11, 12, 14, 15, 16, or 17 and include views of lunar hardware.
If they succeed, there may be an iconic flag in the frame - and we might settle the question of what they actually look like after spending more than 45 years under the sun.
This article was originally published by Business Insider.
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