Way up over our heads satellites and rocket parts orbit the Earth. Sometimes pieces of metal fall towards us. Most burn up in the atmosphere, but not all.

Russian ballistic missile rolls in Red Square during the Victory Day military parade in Moscow.

Flames come out of a satellite falling towards Earth. (Illustration by News Decoder)

Back in 1978, a Soviet nuclear satellite named Kosmos 954 exploded over northern Canada. It spread radioactive debris across northern Saskatchewan and Alberta as well as between the Northwest Territories and what has since become the territory of Nunavut, which Canada established in 1999.

One community continues to feel the impact of the debris — the Dene people of Great Slave Lake, which sits in the southern part of the Northwest Territories. To this day, radiation can be detected on traditional lands and increased cancer rates have been recorded among the population.

We have now entered a new space era and the space industry is taking off. But so are concerns about its impact on the environment — from emissions’ effects on the atmosphere to space debris falling back to Earth. Then there are the unexpected consequences from accidents, like the ones experienced by the Great Slave Lake residents.

Over the next five years, the space industry’s economy is expected to increase 41%. And with a growing industry, the number of objects launched into space will skyrocket.

This trend is already obvious. In less than a decade, the number of objects launched into space has increased more than 1,000%, from 221 launches in 2016 to more than 2,600 in 2023.

Carbon in the troposphere

According to the International Energy Agency, the aviation industry accounted for 2% of global carbon dioxide emissions in 2023. Since the aviation industry uses 100 times more fuel than the space industry, it might seem like aviation is a bigger problem than spaceflights, but there’s a catch: Flights around the globe take place in the troposphere and lower stratosphere, where any emissions dissipate quickly.

When a rocket launches, black carbon — a pollutant from rocket fuel — is released into the stratosphere and mesosphere, where aerosol particles accumulate, absorb solar radiation and warm the surrounding air.

The U.S. National Oceanic and Atmospheric Administration warned in a 2022 statement that while growth in the space industry has many people dreaming beyond our atmosphere, a significant boost in spaceflight activity could harm the Earth’s protective ozone layer.

Recent research has also found aluminum and other metal particles in the stratosphere that are thought to be from satellites and other space debris that have burned up during re-entry to the atmosphere.

The study concluded that these particles won’t likely affect health or impact the environment on the ground, but in the stratosphere’s aerosol layer, which holds the Earth’s protective ozone layer, they could cause changes to the atmospheric chemistry.

When the debris falls to earth

Unplanned re-entries into Earth’s orbit are common — approximately 300 objects enter Earth’s atmosphere each year. Most of them are small and burn up on re-entry. Larger objects that reach the Earth’s surface are most likely to end up in water, which accounts for more than 70% of the world’s surface.

However, larger debris that has made its way back into Earth’s orbit has caused national security concerns.

In 2022, for example, part of a rocket intended for China’s Tiangong space station fell back to Earth. It was estimated to weigh between 17 and 32 tonnes and was about 30 metres long.

It caused havoc in Spain’s airspace by delaying commercial flights, and it became an issue of national security. Eventually, the rocket fragment fell into the ocean without harming any people.

But space debris that falls into the ocean can still affect animals and the environment.

From outer space to the deep sea

A 2021 study that looked at space launches in the United Kingdom warned that animals can be harmed by direct strikes from space debris; by digesting toxic chemicals, such as fuel or small pieces of debris; and by being exposed to excess underwater noise.

Space debris can also smother animals living on the seabed and change the seabed ecosystem by hardening the sea floor.

When space debris is deliberately returned to Earth, it is often directed to the most remote place on the planet — Point Nemo, located in the South Pacific Ocean at 48°52.6′S 123°23.6′W. Far from any other land mass in the Pacific Ocean, Point Nemo has become a planned final resting place for many decommissioned satellites and much space debris.

Scientists have found some evidence that Point Nemo’s location near the South Pacific Gyre, a place where different ocean currents meet, has very low biomass and metabolic activity. Scientists have called this site the least worst option when it comes to disposing of space debris.

Time and more research will likely make the space industry’s impact on the environment more evident. One thing is certain: with spaceflights increasing, we are entering uncharted territory.


Three questions to consider:

  1. What is space debris?
  2. What are some of the dangers of space junk falling to earth?
  3. How do you think we can keep space safe and clean?
Ashley Perl

Ashley Perl is a journalist covering climate, energy and science based in Stockholm. She is currently a fellow in the University of Toronto’s Dalla Lana Fellowship in Journalism and Health Impact.

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