Patches of the moon to become spacecraft graveyards, say researchers | The moon

Patches of the Moon are destined to become spacecraft graveyards where dead lunar satellites and other defunct hardware can crash to the ground, far from sites of cultural and scientific significance, researchers say.

The number of satellites circling the Moon is expected to explode over the next two decades, as space agencies and private companies build lunar bases and embark on mining operations and build scientific instruments on this barren terrain.

The renewed activity will be supported by constellations of lunar satellites for positioning, navigation and communications. But when satellites run out of fuel, operators have little choice but to steer them toward the ground, where they will be broken into pieces.

“These satellites will have to crash into the Moon, so it will potentially become a landfill,” said Dr Fionagh Thomson, a senior research fellow at Durham University, who convened a panel of experts on the issue at the Space-Comm meeting in Glasgow in December.

Beyond scattering parts of the satellites on the surface, researchers worry that if dozens of dead satellites fall on the Moon, they risk causing damage to buildings, scientific instruments, historic sites such as early astronaut footprints and pristine sites of scientific interest.

With impact speeds of 2 km per second, the collisions will produce intense vibrations, which could disrupt sensitive instruments that scientists want to build on the Moon. Scars carved into the surface are expected to extend tens of meters and produce vast clouds of abrasive dust that could obscure telescopes and damage equipment.

“This is not an immediate concern, given the size of the Moon, but the more lunar satellites there are, the greater the risk that some will crash into scientifically or culturally sensitive places,” said Professor Ian Crawford of Birkbeck, University of London. “We need a plan to move forward.”

Satellite operators regularly use Earth’s atmosphere to dispose of dead satellites drifting around the planet. Every year, thousands of defunct satellites are incinerated upon re-entry. But since the Moon has no atmosphere, lunar satellite operators need other solutions.

And they will need it soon. More than 400 lunar missions are planned over the next two decades. They include the NASA-led Lunar Gateway, a space station that will orbit the Moon, and the Artemis Base Camp on the surface. A second lunar base is planned by China and Russia.

Next year, the European Space Agency will launch the Lunar Pathfinder satellite, a test bed for its Moonlight lunar satellite constellation that is expected to be operational by 2030. Work is underway on how to dispose of the Lunar Pathfinder at the end of its eight-year lifespan.

Lunar satellite operators have three main options. With a propulsion unit and enough fuel, a satellite can take off and orbit the sun. But it is expensive. Alternatively, it could move to a more distant lunar orbit, but the moon’s irregular gravitational field makes this difficult. Finally, satellites can crash into the ground, but this requires careful planning.

Sarah Boyall, head of the UK Space Agency’s Regulatory Office, said the UN Lunar Consultations Action Team (Atlac) and the Inter-Agency Space Debris Coordination Committee (IADC), which the UK currently chairs, are working to establish best practices for the disposal of lunar satellites.

Spacecraft graveyards are one of the main contenders, with operators required to crash old satellites in designated locations or in giant craters that would contain the dust kicked up during impact. The UK Space Agency and signatories to the US Artemis Accords, a set of principles for future space exploration, are continuing this approach.

“Establishing graveyard zones on the Moon is the most practical solution,” said Ben Hooper, senior project manager for Lunar Pathfinder at SSTL, the Surrey-based satellite manufacturer. “Designating specific regions as ‘impact zones’ would limit the spread of human objects across the lunar surface, thereby preserving other areas for scientific exploration and future operations.”

Charles Cranstoun, head of ESA’s Moonlight program office, said that when the time comes, the satellites would crash to the surface in a controlled manner “in specified areas”, to avoid “sites of scientific interest and historical significance and ongoing missions”.

John Zarnecki, emeritus professor of space science at the Open University, said satellites crash-landing in graveyard areas could be put to good use, as the impacts generate seismic waves at known locations, to shed light on the structure of the moon. “If you have an object of known mass, geometry and speed, and you know roughly where it hit, it’s a fantastic seismometry experiment,” he said.