The Growing Concern Over Starlink Satellites and Space Debris
A renowned astrophysicist has raised serious concerns about the potential dangers posed by Elon Musk’s Starlink satellites, which are currently deorbiting at a rate of one or two per day. Jonathon McDowell, who spent 37 years at the Harvard-Smithsonian Center for Astrophysics, has warned that if the stratosphere is damaged—particularly its ozone layer—more harmful UV radiation could reach the Earth’s surface, leading to increased cases of skin cancer, cataracts, and eye damage in humans.
McDowell highlighted that more than 25,000 pieces of orbital debris are already circling the planet. This debris, often referred to as ‘space junk,’ consists of dead satellites, spent rocket stages, or fragments from collisions. Currently, around 8,000 of SpaceX’s satellites are operating overhead, with more expected to be launched by Musk and other companies and countries.
The Rise of Space Debris and Regulatory Warnings
In 2023, the Federal Aviation Administration (FAA) warned Musk that his satellites had the potential to seriously injure or kill someone by 2035. However, Musk dismissed the analysis as “preposterous, unjustified and inaccurate” in a letter to the FAA and Congress. SpaceX’s principal engineer at the time, David Goldstein, called the report “deeply flawed.”
Despite this, SpaceX has acknowledged that not all satellites fully disintegrate upon reentry. In February of this year, the company released a statement explaining that it began to cycle out older satellites designed to orbit for five years. While this proactive approach comes at the cost of losing satellites that are still serving users effectively, SpaceX believes it is necessary to keep space safe and sustainable.
The Risk of Kessler Syndrome
As more satellites are launched into low-Earth orbit, the number of reentries is expected to increase. McDowell explained that, with all constellations deployed, there could be around 30,000 low-Earth orbit satellites, along with another 20,000 satellites at 1,000 km from Chinese systems. He warned that this could lead to a scenario known as Kessler syndrome—a theoretical situation where high numbers of objects in low-orbit result in a chain reaction of collisions, creating even more debris.
“If just one percent of Starlink satellites [assuming the planned 30k constellation] die on station, that’s still 300 satellites,” McDowell said. “Three hundred big satellites could tip low Earth orbit into Kessler.”
McDowell noted that the region of space closest to succumbing to Kessler syndrome is between 600 to 1,000 kilometers, which is already filled with old Soviet rocket stages and other debris. Adding more satellites to this area increases the likelihood of such a scenario occurring.
Environmental Impact of Satellite Reentries
Beyond the risk of space debris, scientists are also concerned about the environmental impact of satellite reentries. Researchers like atmospheric chemist Daniel Murphy of the National Oceanic and Atmospheric Administration have pointed out that almost no one is thinking about the environmental impact on the stratosphere.
A study by Murphy and colleagues found that satellites burning up during reentry release metal vapors that condense into aerosol particles. These particles can descend into the stratosphere, potentially affecting the ozone layer. Around ten percent of these particles contain aluminum, lithium, and copper, among other toxic metals.
The study warned that planned increases in the number of low-Earth orbit satellites could cause up to half of stratospheric sulfuric acid particles to contain metals from reentry. Aluminum, a common material used in satellites, could react with hydrogen chloride to form aluminum chloride, which may contribute to ozone depletion.
The Future of Space Sustainability
Experts are calling for a shift toward a more sustainable approach to space operations. Adam Mitchell, a materials engineer at the European Space Agency, emphasized the importance of an in-space circular economy, including refueling, repairing, recycling, and relaunching from space.
Pierre Lionnet, managing director of ASD Eurospace, expressed concerns about whether SpaceX is creating a major problem for the future. McDowell, however, remains uncertain about whether it is already too late to prevent potential damage to the upper atmosphere.
Ongoing Questions and Uncertainties
As the number of satellites in orbit continues to rise, many questions remain unanswered. Is the rapid increase in Starlink reentries a ticking time bomb for Earth’s atmosphere? Could the growing number of satellites pose a threat to technologies like Starlink? What risks do astronauts face as space debris accumulates?
The future of space sustainability is a critical issue that requires careful consideration and action. As we continue to explore and utilize space, ensuring the safety and health of our planet becomes more important than ever.
