Starlink, owned by the world’s richest man, Elon Musk, has launched thousands of satellites into space to improve internet communication in remote areas and on airplanes. However, every day, some of these satellites fall from the sky and burn up in our atmosphere. These satellites, in low Earth orbit, have recently become a significant environmental phenomenon, raising growing concerns among the scientific community.
So far, SpaceX has launched more than 8,000 Starlink satellites into space, and their number is expected to reach tens of thousands in the coming years. Each satellite, weighing around 250 kg., is designed to last only about five years.
At the end of their operational life, they are directed back toward Earth, where they burn up and disintegrate in the upper layers of the atmosphere. At first glance, this seems like a responsible process that prevents the accumulation of hazardous space debris. However, it turns out that this process has significant environmental consequences, and recently, experts worldwide have warned about the most severe risks to humanity.
"For a satellite to maintain its orbit in space, it must move at an enormous speed," explains Prof. Meir Ariel, head of the Space Engineering Center at Tel Aviv University. "At an altitude of 500 km., where the satellites operate, gravitational force is less than about 10% of Earth's gravity. To maintain its orbit around Earth, the satellite must balance Earth's gravitational pull with centrifugal force.
The rocket that propels the satellite into space moves at a speed of 29,000 kph., giving the satellite the necessary speed boost. Since space is a vacuum with no air resistance, the satellites continue at this speed, though their velocity gradually decreases due to friction with the outermost layers of the atmosphere. Over time, they encounter more atmospheric resistance until they completely burn up, leaving behind space debris."**
As mentioned, when Starlink satellites re-enter the atmosphere, they heat up to extremely high temperatures, causing their breakdown and the release of tiny aluminum oxide particles. This material, which constitutes about 40% of the satellite’s weight, accumulates in the upper layers of the atmosphere and remains there for decades.
As the number of satellites increases, so does the amount of aluminum oxide released into the atmosphere. In 2022 alone, falling satellites introduced 41.7 tons of aluminum into the atmosphere, a significantly higher amount than the natural release from tiny meteorites. According to researchers' forecasts, this amount could rise to 360 tons per year in the coming years—an increase of hundreds of percent compared to current natural levels.
These particles do not remain without effect: Scientists fear they could act as a catalyst for chemical reactions that harm the ozone layer. While aluminum oxide does not directly break down ozone molecules, it accelerates chemical processes that lead to faster ozone depletion. The alarming implication is that a single aluminum particle could contribute to the destruction of thousands of ozone molecules over decades, potentially causing severe damage to the ozone layer, which protects us from harmful ultraviolet radiation.
The environmental impacts of Starlink satellites falling could be particularly severe given the recovery of the ozone layer since the 1980s following the ban on CFC gases. Today, scientists warn that the aluminum released from satellites could reverse this progress, slow the ozone layer’s recovery, and even undo the positive trend achieved so far.
This damage could lead to a renewed increase in ultraviolet radiation, which would result in higher rates of skin diseases and cancer, harm to the immune system, and damage to agricultural crops and sensitive ecosystems such as the marine food chain.
But this issue is not only about the environment and human health—the economic damage associated with this phenomenon is also significant. The costs of launching and frequently replacing satellites are enormous. One of the most notable incidents occurred in 2022 when Elon Musk’s SpaceX lost 38 newly launched satellites shortly after deployment due to an unexpected geomagnetic storm. This event caused financial damage worth millions of dollars and led to the sudden release of aluminum particles into the atmosphere.
Another major problem is the lack of regulatory oversight. As of today, no binding international regulations govern the air pollution caused by falling satellites. In the United States, the Federal Communications Commission (FCC), which licenses communication satellites, does not address the aluminum pollution resulting from satellite destruction. Commercial companies are not subject to environmental regulations in this area. The United Nations has also not yet succeeded in drafting binding agreements, and efforts to limit pollution are still in their early stages.
"Until five years ago, around a thousand satellites were launched into space annually," explains Prof. Ariel. "Just last year, Musk’s Starlink had 7,000 satellites, and they aim to reach 30,000. This means more space pollution, an increased risk of satellite collisions, and more debris that will burn up. Climate and environmental scientists are rightly concerned that this will spiral out of control, harming the atmosphere, exacerbating the greenhouse effect, and leaving behind hazardous pollutants that threaten human health."
The scientific community is raising a clear call for the development of technological solutions to minimize the damage. Several recent studies suggest exploring ways to reduce aluminum use in satellites or designing steeper re-entry paths to limit the particles’ presence in the upper atmosphere.
Experts recommend considering the possibility of positioning satellites in higher orbits after their operational life, where they would not impact the atmosphere, or requiring satellite companies to return their satellites to Earth instead of allowing them to burn up in space and cause pollution. These solutions may increase launch costs, but they are essential for protecting our planet.
"International agreements are attempting to reach a consensus on possible solutions," concludes Prof. Ariel. "What is clear is that if no action is taken to reduce pollution, the world may face severe damage that will be difficult to repair."
