Junk in Space and on the Moon

Written By Edgar Salus

People think of space as vast and empty. However, junk is filling up the near-Earth environment and recently, some of that junk has even made its way back.

An image of the object that fell through the roof of Alejandro Otero's home in Naples, Fla. PHOTO BY ALEJANDRO OTERO /X

As NASA confirmed, a mystery object that crashed through the roof of a Florida home in March 2024 was a chunk of space junk from equipment discarded at the International Space Station three years earlier. The list of incidents of space debris falling to Earth and impacting our lives is getting longer. 

What is space junk and how does it get there?

Space junk is basically any machinery or debris left by humans in space. Items can range in size from large objects such as failed or dead satellites to tiny objects such as paint flecks and nuts and bolts.

While there are about 2,000 active satellites orbiting Earth at the moment, there are also 3,000 dead ones littering space. Further, there are around 34,000 pieces of junk bigger than 10 centimeters in size and millions of smaller pieces. Tiny pieces of junk might not seem like a big issue, but that debris is moving at around 24,000 km/h which is 10 times faster than a bullet. At that speed, even a fleck of paint could puncture a spacesuit or destroy a sensitive piece of electronics and therefore have a disastrous consequence. 

Space junk around Earth (Getty Images/MARK GARLICK/SCIENCE PHOTO LIBRARY)

All space junk is the result of countries launching objects from Earth and the amount of debris has increased dramatically since the 1960s. Space junk remains in orbit until it re-enters the atmosphere. 

Some objects in lower orbits of a few hundred kilometers can return quickly. NASA estimates that about 44 tons of space debris fall into Earth’s atmosphere each day. About 95% of it burns up so that they don’t reach the ground. However, debris or satellites left at higher altitudes of 36,000 kilometers can continue to circle Earth for hundreds or even thousands of years. 

The risks of space junk

At the moment, the biggest risk space junk poses is to (other) satellites in orbits as they have to move out of the way to avoid collisions. In total, across all satellites, according to NASA, hundreds of collision avoidance maneuvers are performed every year, including by the International Space Station (ISS). 

In 1978, NASA scientist Donald Kessler described a scenario where collisions between orbiting pieces of debris create more debris, and the amount of debris grows exponentially, potentially rendering near-Earth orbit unusable. This is officially called the “Kessler syndrome.”

(NASA)

Notable items that have been left on the Moon

In addition to debris in orbits, there are lots of items that have been left on the lunar surface during moon missions. There are many reasons why objects have been left behind. Often it is to make room for other items (rocks etc.) for the return flight. These items include moon buggies and other lunar equipment and almost 100 bags of human waste. Scientists are keen to one day bring the human waste back to Earth, to study how its time on the Moon has affected it. However, for the time being the bags with human waste lie on the Moon’s surface. Other times the reasons why items were left behind were more sentimental. In 1972 Apollo 16 astronaut Charles Duke left a framed family photo on the Moon’s surface which has by now most likely been bleached completely white by the exposure to the Sun’s radiation. 

In 1971 Apollo 15 astronaut David Scott carried out a similar experiment to the one Galileo Galiei is said to have conducted in the late 16th century. Galilei supposedly dropped two objects of different masses from the Leaning Tower of Pisa to prove that the speed with which they fell was independent of their mass. Astronaut Scott dropped a feather and a hammer at the same time and the world watched as they fell at the same speed and landed on the Moon’s surface at the same time (where they still are today).

Each lunar landing was marked by the planting of a flag. Because there is no wind on the Moon the flags would never fly. Therefore, the flags were all constructed with extendable poles so that the flags could be seen when unfurled. Currently, there are a total of six US flags on the Moon. 



Nobody is in charge

According to the United Nations Outer Space Treaty of 1967, no country can “own” the Moon or any part of it and celestial bodies should only be used for peaceful purposes. But the treaty says nothing about how space resources can be used. The United Nations Moon Agreement of 1979 declared that the Moon and its natural resources are the common heritage of humanity, but the United States, Russia and China never signed this treaty.

The lack of globally accepted regulations and restrictions means that nobody is responsible for cleaning the Moon and our orbit.



The Artemis Accords

In 2020 NASA in coordination with the US Department of State formulated the so-called Artemis Accords in order to directly address the need to combat the growing issue of space debris. The Artemis Accords promote ‘best practices and norms of responsible behavior’ when it comes to lunar exploration. As of April 2024, 30 countries have signed the Accords, but the list does not include China and Russia. Further, the Accords merely constitute non-binding principles for cooperation peacefully in space and private companies are not party to the Accords, either. 

The lack of binding nature and the current gold rush approach to space exploration means that space junk will continue to accumulate and with it the related problems and dangers. 


 
Edgar Salus
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