In July 1969 Neil Armstrong and Buzz Aldrin made history as the first human beings to land on the Moon’s surface. Five more crewed missions made it to the Moon in the years that followed before the Apollo program ended in 1972. Add to that the numerous uncrewed missions since Soviet probe Luna 2 first crashed on the Moon in 1959. Altogether, we have now delivered about 500,000 pounds of human artifacts to our natural satellite’s surface. So what exactly have we left on the Moon?

Some of what has been left is obvious. More than 70 spacecraft vehicles remain on the Moon for the simple reason that they are heavy and not worth the cost to bring back. They account for most of the mass left on the Moon.

Some of it is waste from the trip that the astronauts dumped when they got to their destination. Aside from trash—from food packaging to wet wipes—nearly 100 packets of human urine and excrement have been discarded.

The Apollo astronauts also dumped tools and television equipment that they no longer needed. They were shedding weight from their command modules so they could maximize the amount of samples they could bring back to Earth from the Moon’s surface. In exchange for what they left behind, the Apollo missions were able to bring back some 850 pounds of Moon rocks and lunar soil.

Then there’s all the memorabilia. Six American flags have been planted on the surface of the Moon. They’re likely faded now, as is the photograph that Charles Duke left behind of himself with his family. There are also two golf balls up there somewhere after Alan Shepard tried his hand at putting in the low gravity.

The landing module of Apollo 11 is still there, marked with a plaque that reads: “Here men from the planet Earth first set foot upon the Moon July 1969, A.D. We came in peace for all mankind.” The message exhibited the triumph of the lunar landing for humankind as a whole, shepherding humanity to new frontiers—in spite of the Cold War between the United States and the Soviet Union, which had sparked the race to the Moon in the first place. In a similar spirit, the American astronauts left two medals that had been awarded to the late Soviet cosmonauts Yuri Gagarin and Vladimir Komarov, space pioneers who perished in tragic accidents.

Gagarin and Komarov were not the last people to be immortalized on the Moon. In 1998 astrogeologist Gene Shoemaker’s ashes were sent aboard an exploratory mission to the Moon, where they now lie amid the lunar dust.

In just 50 years the human footprint has certainly left an impression on the lunar surface—in more ways than one. One of the most famous images from the Moon is Buzz Aldrin’s photograph of his own footprint. With virtually no atmosphere (and therefore no wind to erode the soil), that same footprint is probably still there. As NASA looks to revive its crewed missions to the Moon by 2024, humans are almost certain to leave more footprints in the years to come.

Read the original article on britannica.com.

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