The world’s next big environmental problem could come from space

SpaceX’s Starlink is the largest of them all. The constellation currently consists of approximately 6,500 satellites and is expected to grow to more than 40,000 satellites sometime in the 2030s. Other megaconstellations, including Amazon’s Kuiper, France’s E-Space, and China’s G60 and Gonet projects, are in the pipeline. Each satellite may contain thousands or even tens of thousands of satellites.

Megaconstellation developers don’t want their spacecraft to fly like the old government-funded spaceships that last two to three decades. They hope to replace these orbiting network routers with newer, better technology every five years and then send the old routers back into the atmosphere to burn up. The rockets required to launch all these satellites emit their own mix of pollutants (their upper stages also burn up in the atmosphere).

The amount of space debris vaporizing in Earth’s atmosphere has more than doubled in the past few years, said astronomer Jonathan McDowell of the Harvard-Smithsonian Center for Astrophysics, who is leading a second career Space Debris Tracker.

“We used to see about 50 to 100 rocket stages re-entering every year,” he said. “Now our goal is 300 a year.”

In 2019, approximately 115 satellites burned up in the atmosphere. McDowell said that as of late November 2024, the number of satellite re-entries had reached 950, setting a new record.

The quality of vaporized space junk will continue to grow with the size of the satellite fleet. The annual amount of waste could reach 4,000 tons by 2033, according to estimates from a September workshop on “Protecting the Earth and Outer Space from Spacecraft and Debris Disposal” held at the University of Southampton in the UK.

Crucially, much of the ash from these re-entries will remain suspended in the thin mid-atmosphere for decades, if not centuries. But getting precise data on satellite burnout is nearly impossible because the region where it occurs is too high for weather balloons to measure and too low for sounding instruments on orbiting satellites. The closest scientists can get is remote sensing of the satellite’s final moments.

change chemical reactions

The business jet that took off from Easter Island in September was turned into a science laboratory, and none of the researchers on board witnessed the moment the salsa swarm exploded into a fireball over the deep Pacific Ocean. In bright daylight, the brief explosion looks as vivid as the full moon at noon. However, the plane’s windows are covered with dark fabric (to prevent internally reflected light from affecting measurements), allowing only the camera lens to peek out, said Jiří Šilha, CEO of Astros Solutions, a Slovakia-based space scenario solutions company. Awareness develops new technologies for space debris monitoring and coordinates observation activities.