The Apollo landing zones are incredibly unique. On Earth, preserving a historic site usually comes with a multimillion dollar price tag to cover ongoing maintenance. But on the moon, where there's no weather to wear theses sites away, preserving them is as simple as never going near them.
Neil Armstrong's boot prints will never fade. There's also science at those sites that ought to be left alone; the bacteria in fecal collection bags there could be of interest to future biologists.
But there's more than just waste, spent descent stages, and lunar rovers in six areas on the moon's surface. There are personal effects that humanize the missions - the whole program - and tell the stories of the individuals who walked on the surface.
Armstrong and Buzz Aldrin, whose Apollo 11 mission patch didn't list theirs and Michael Collins' names, brought another crew's insignia to the surface. After their two-and-a-half-hour walk, the crew left an Apollo 1 patch bearing the names of the three astronauts who died in the pre-launch fire in 1967. It joined the American flag and official mission plaque as permanent fixtures at the Sea of Tranquility.
Apollo 12 also paid tribute to a fallen colleague. Clifton Curtis Williams was in line to serve as lunar module pilot on the lunar flight when he was killed when his T-38 jet entered a fatal spin and crashed. The crew's commander Pete Conrad brought Alan Bean into the crew to take Williams' place. Suddenly making the jump from rookie to moonwalker, Bean paid tribute to Williams by adding a fourth star to the crew's mission patch.
He also took Williams' naval aviator "wings of gold" pin to the moon and laid it to rest on the Ocean of Storms. Bean's own silver astronaut pin is up there too, inside the Surveyor crater. He wouldn't need it after the mission since it would be replaced with a gold one, and couldn't think of a better place to leave it.
Conrad and Bean also left a small, automatic camera timer on the surface. Conrad had conspired with support engineers to sneak the item on board to get pictures of him and Bean together. But when the time came to take the shot, they couldn't find the timer. Bean eventually found it, but it was too late to set up the shot. He threw it as far from the Lunar Module Intrepid as possible.
In 1971, after finishing more serious surface activities, commander Alan Shepard added a six-iron golf club head to the handle of his contingency sample return container. Then he pulled a golf ball out of his pocket. He dropped the ball to the surface and took a one-handed swing. On the third try he connected with the ball and sent it flying for "miles and miles." That golf ball is still lying somewhere near the Fra Mauro crater.
The entire Duke family took a trip to the moon in 1972; at least, their photographic likeness did. Apollo 16 lunar module pilot Charlie Duke brought a small family portrait with him to the Descartes highlands. On his third EVA, he dropped the photo in its protective case into the lunar dust, pausing to snap a few pictures of it before moving on with his activities.
There are other personal items on the lunar surface, infusing the landing sites with stories that bring humanity into the space race. As we get further away from the moon landings in time, this becomes an equally important aspect to preserve. Disturbing the sites is almost akin to erasing the men that went to the moon, while preserving them also preserves the individual characters that made the journey.
Image: On 19 Nov. 1969, Apollo astronaut Alan Bean carried two sub packages of the Apollo Lunar Surface Experiments Package (ALSEP) during the first Apollo 12 extravehicular activity (EVA). Human activities, like Bean's, will be preserved as areas of historical interest. Credit: NASA (high-res photograph)