THE moon looks pristine from our vantage point. But there have been six crewed moon landings and about 20 successful rover and lander missions on its surface, and these have left rather a lot of mess behind them. Both intentionally and by accident, we have scattered detritus across the lunar surface during our attempts to land there and as the Apollo astronauts explored the desolate landscape.
Now a new space race is heating up, and astronauts may soon return to what Buzz Aldrin called its 鈥渕agnificent desolation鈥. If they do, they may well come across some of the estimated 187,000 kilograms of rubbish strewn across it. Here is some of what they might find.
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Dead cotton plants
颁丑颈苍补鈥檚 Chang鈥檈 4 rover landed on the moon in January, bringing with it the first moon garden. In a sealed biosphere, cotton, oilseed rape and potato became the first plants that we know of to germinate on another world. After the probe lost power, the plants probably died as the freezing lunar night fell over them. But this experiment is a landmark step towards building a flourishing lunar base where humans can farm their own crops.
Lots of human faeces

It is nothing to be embarrassed about: everyone needs to defecate, even space explorers. And when the Apollo astronauts were planning their trip home, they jettisoned as much weight from the spacecraft as they could to make room for the cargo of heavy moon rocks they were bringing back to Earth. The materials they ejected included 96 bags of faeces and urine.
Fallen Astronaut memorial

In a long, narrow depression to the west of the Montes Apenninus, a mountain range in the moon鈥檚 northern hemisphere, is a memorial to eight American astronauts and six Soviets who died in the pursuit of space travel. The 8.5-centimetre metal sculpture is in the crude shape of an astronaut. It was commissioned and placed on the moon by the crew of Apollo 15, alongside a plaque commemorating their lost comrades.
Discover more about NASA鈥檚 missions: Explore four NASA space centres on a 快猫短视频 Discovery tour
Mortar launchers

To learn about the interior of the moon, Apollo astronauts used explosives to give it a good thump and then measured the ensuing sound waves wobbling through its rocky subsurface. The explosives were either remotely launched after they left the moon, or were set to go off days after a grenade-like pin was pulled by astronauts, who then made their escape using lunar buggies. The mortar launchers remain on the moon, but who knows if they would still work after decades of exposure to the harsh conditions.
The secrets to David Copperfield鈥檚 magic tricks
The most recent attempt to land on the moon took place in April 2019 and ended with the crash of the privately funded Beresheet spacecraft. However, its payload was well protected and might just have survived the impact. The lander was carrying a disc with a 30-million page data library that includes the English version of Wikipedia, tens of thousands of books and the technical instructions for David Copperfield鈥檚 illusions. An orbiting NASA craft has spotted the crash site, so future explorers would know where to look for the answers.
Two golf balls
Apollo 14 astronaut Alan Shepard went to a lot of trouble to have a bit of fun on the moon. When he boarded the spacecraft, he brought with him two golf balls and a specially designed golf club head, which he attached to the handle of a soil and rock sampling device to forge a makeshift club. He hit two shots: the first sliced to the side and rolled into a crater, but the second flew about 180 metres. Fore!
A falcon feather

Galileo is said to have dropped two balls of different weights off the Leaning Tower of Pisa, proving that the acceleration they experienced due to gravity was unrelated to their mass when they hit the ground at the same time. Apollo 15 astronaut David Scott performed a version of this experiment using a hammer and a falcon feather taken from a US Air Force mascot. The vacuum of space eliminates air resistance and the feather hit the lunar soil at the same time as the hammer.
With NASA and others eyeing a return to the moon, it looks likely that humans will return in the not-too-distant future. This time we ought to go forth with a cleaner mentality, says , a lunar geologist at the University of Manchester, UK.
We may as well leave the debris from our past excursions where it is, she says. 鈥淚f we clean up the mess, we will also be disturbing the lunar environment.鈥 So what is there can stay as a kind of monument to explorations past.
But we should take better care over what we abandon there in the future. The moon is a finite resource, and we can鈥檛 just trash it and hope that we won鈥檛 run into the same problems we have seen on Earth. 鈥淭here鈥檚 a revival of interest in the moon without a great pondering,鈥 says Assis Fernandes. 鈥淒o we want to do the same damage there that we鈥檝e done to this planet?鈥
Article amended on 21 August 2019
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