The Moon is a long-term repository for humanity’s early ventures into space. Over six decades of exploration, both crewed and uncrewed missions have systematically deposited hardware and various artifacts onto the lunar surface. This collection of human-made material testifies to the space race and subsequent missions. Understanding the full extent of this collection requires cataloging the diverse range of objects left behind.
Defining Lunar Debris
Lunar debris encompasses a varied collection of material, ranging from massive spacecraft components to small, personal mementos. The largest items are the descent stages of lunar landers and the three functioning Lunar Roving Vehicles used during the later Apollo missions. These pieces of intact hardware make up the bulk of the total mass left behind.
A second category includes spent equipment and scientific instruments discarded by astronauts to lighten the load for the return journey. This material includes:
- Cameras
- Tools like shovels and tongs
- Power packs
- Boots worn on the surface
Additionally, nearly 100 bags of human waste (feces, urine, and vomit) were intentionally jettisoned.
Finally, the surface is scattered with commemorative items that possess cultural value. These range from the six American flags planted by the Apollo crews and plaques affixed to the lander legs, to a small aluminum statue called Fallen Astronaut. Other personal items include a family photograph and a golden olive branch intended to symbolize peace.
The Total Mass of Objects Left Behind
The accumulation of hardware, spent equipment, and mementos has resulted in a large mass of terrestrial material resting on the Moon. Conservative estimates place the total weight of human-made objects at over 187,400 kilograms, or approximately 187 tonnes. Some calculations suggest the figure may be closer to 200 tonnes.
The material is spread across many sites, comprising thousands of individual components. This count includes over 70 spacecraft that have either landed softly or impacted the surface over the decades of exploration.
The spent third stage (S-IVB) of the Saturn V rockets accounts for a large fraction of the total mass. These stages were intentionally crashed into the lunar surface after propelling the Apollo missions. Although the total number of objects is in the thousands, the weight is heavily skewed toward this substantial rocket hardware and the six Apollo descent stages.
The Source and Distribution of Material
The vast majority of the debris originates from the space programs of the United States and the former Soviet Union during the initial space race. The six successful American Apollo landing sites are the most concentrated areas of artifacts, containing the descent stages, rovers, tools, and waste discarded by the astronauts.
The material is also distributed across various crash and impact locations from both successful and unsuccessful missions. The Soviet Union’s Luna program and American robotic missions like Ranger, Surveyor, and Lunar Orbiter all left wreckage or decommissioned hardware. More recent contributions come from nations like China, India, and Israel, whose landers and probes have joined the collection of artifacts.
The heaviest single objects, the Saturn V S-IVB stages, are located at five distinct impact sites. They were deliberately aimed at the Moon to create seismic events for study by deployed scientific instruments. This distribution pattern includes both meticulously organized landing sites and scattered debris fields resulting from intentional or accidental high-speed impacts across both the near and far sides of the Moon.
Implications for Future Lunar Exploration
The existing field of lunar artifacts presents several considerations for the next generation of space exploration. From a scientific standpoint, the presence of these materials offers a unique, unplanned experiment in astrobiology. Scientists are interested in the 96 bags of biological waste to see if any microorganisms could have survived the harsh lunar environment.
The debris can pose a physical hazard for future missions. High-velocity impacts from micrometeorites could cause existing hardware to fragment, creating localized secondary debris particles. Lunar environmental stewardship is also a growing concern, with international efforts like the Artemis Accords urging signatories to limit the creation of new debris.
The historical significance of the existing landing sites necessitates heritage preservation. Policy discussions center on protecting these sites from disturbance by future robotic or crewed missions, treating them as archaeological locations. This ensures that the physical evidence of humanity’s first steps on a celestial body remains available for future study and appreciation.