What's There
- ReflectorsPanels made of mirrored prisms. Lasers are still fired at them from Earth to measure the distance to the Moon with centimeter-level accuracy.
- Three VehiclesThe electric lunar rovers from the expeditions were left where they stood: bringing them back would have required extra fuel for the ascent.
- TrashBags of waste, life-support backpacks, and boots. Everything unnecessary was dumped to lighten the ascent stage.
- A MemorialA plaque bearing the names of astronauts and cosmonauts who died, along with a small figurine, was left by the crew as a memorial.
The first item is the only one that still provides scientific data. The reflectors need no power: they simply return the beam exactly where it came from, and they have been working for more than half a century.
Thanks to them, we know that the Moon is moving away from Earth by a few centimeters a year. The idea behind the measurement is simple, but carrying it out is incredibly precise: scientists measure how long light takes to travel there and back.
Why It Was Left Behind
About this share of the mass delivered to the surface was brought back: only samples and people could be lifted off the Moon
Every kilogram at takeoff required fuel, and that fuel had to be brought along too. So before taking off from the surface, the astronauts dumped everything they could: cameras, tools, backpacks, and boots, just to lift the rock samples.
The footprints won't disappear anytime soon. There is no wind or water, and meteorite dust erases them extremely slowly. Estimates suggest that the bootprints will last for millions of years.
That's why people are discussing ways to protect the landing sites. One proposal is to treat them as monuments and keep future spacecraft at a distance: one bad landing nearby could bury in dust what has survived for half a century.
What still works on the Moon?
Why were so many things left on the Moon?
Sources
- The Moon's surface holds landing stages, vehicles, scientific instruments, and everyday items from the expeditions
- corner-cube reflectors are still used for laser ranging, which shows that the Moon is moving away from Earth by a few centimeters a year
Next in the “The Moon” series
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