Space junk: The rising threat of satellite metals to earth's stratosphere

In January 2025, over 100 communications satellites were deliberately destroyed by burning up in Earth's atmosphere, a process designed to prevent satellite debris from littering space or falling uncontrollably to the ground. This "designed demise" is a measure to keep space clear, with regulations requiring satellites to deorbit after five years to reduce space junk. However, this practice may have unintended consequences for the Earth's atmosphere.

As these satellites vaporize upon re-entry, they release a variety of metals, including aluminium, copper, lithium, and niobium, into the stratosphere, the layer of the atmosphere 10-50 km above Earth's surface. With over 11,000 satellites currently in orbit, and requests for an additional one million launches, an article by The Economist points out that the quantity of these materials entering the atmosphere is set to increase significantly.

Atmospheric chemists, such as Daniel Murphy from the National Oceanic and Atmospheric Administration, have expressed concerns over the potential unknown effects of these increasing metal particles on atmospheric chemistry.

While Earth has naturally been exposed to meteoroids and cosmic dust for billions of years, the introduction of satellite-derived metals represents a new challenge. In 2019, humans added around 890 tonnes of material to the atmosphere, with this mass steadily increasing. Unlike natural cosmic dust, the article highlights that space debris brings a different set of metals, including ten times more lithium, which could have unforeseen consequences for the atmosphere. One study found that up to 10% of aerosol particles in the stratosphere now contain metals from spacecraft.

These metals could trigger chemical reactions that may have long-term environmental effects. According to The Economist, aluminium could combine with oxygen to form alumina, creating surfaces for further chemical reactions, potentially releasing chlorine that can damage the ozone layer. Other metals like copper could act as catalysts, speeding up these reactions without being consumed, potentially accelerating harmful processes indefinitely.

However, the full extent of these consequences remains unclear due to limited research, monitoring tools, and oversight. Currently, most satellite launches are conducted by SpaceX, with its Starlink constellation of nearly 7,000 satellites contributing significantly to the problem. Despite FCC regulations requiring environmental reviews for satellite launches, mega-constellations of over 100 satellites are exempt from such scrutiny. In 2022, a congressional auditor recommended that the FCC assess the environmental impact of these large constellations, but no review has been published yet.

The article also highlights plans from other countries and regions, such as China and the European Union, which are developing their own satellite mega-constellations. China, for instance, intends to launch approximately 38,000 satellites, while Rwanda has filed a request for 327,000 satellites. While some countries, like the EU, are considering environmental regulations for space activities, China’s laws are less specific, focusing on the protection of the space environment.

Solutions to mitigate these effects include developing smaller satellites, using alternative materials like carbon fiber or wood, or rethinking the satellite deorbit process. Some scientists suggest extending satellite lifespans to reduce the need for constant launches, or sharing mega-constellations between countries. However, the article warns that increasing international tensions may make such collaboration challenging and underscores the need for better regulation and oversight to prevent space-related environmental damage.

By Nazrin Sadigova