New images from NASA's Lunar Reconnaissance Orbiter Camera confirm that five of the six American flags on the moon survive.
When NASA launched the Lunar Reconnaissance Orbiter in 2009, of course scientists were hoping the spacecraft would add to the knowledge we have of our sole natural satellite -- its geography, topography, weather, and so on. But one question many were hoping the LRO would answer had little to do with the moon's environment: What had become of the Apollo sites, left behind by the humans who visited the surface between 1969 and 1972? Mark Robinson, the principal investigator for the LRO Camera (LROC), says questions about the Apollo sites were "the most common" ones posed to the LROC team.
In particular, had the six American flags planted on the moon survived? The conditions were not friendly, Geologist Paul Spudis wrote:
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 colors 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.
Historian and editor of collectSpace.com, Robert Pearlman, raised the separate issue of the quality of the flags. "We didn't design a special American flag to go to the moon to last thousands of years," he said. "They literally sent out a secretary to the nearby Sears and bought an off-the-shelf flag and modified it. The natural disintegration of the flag's material in the harsh conditions on the moon's surface is to be expected."
But now Robinson says that he is "a bit surprised" that the flags could survive the harsh conditions. However, he writes, "They did."
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. 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 continues, "The most convincing way to see that the flags are still there, is to view a time series of LROC images taken at different times of day, and watch the shadow circle the flag," as a video posted to YouTube by the LROC team shows below.
More images of each of the Apollo landing sites are available on the LROC website, including a flip-book feature in which the shifting shadows are clearly visible.
Of course, the flitting shadows don't provide much clues as to the condition of the flag, which in all likelihood is a faded, tattered, white ghost of its former self.