Rising Space Waste
Leonard Schulz, Technische Universität Braunschweig, Germany, and colleagues have studied how reentering satellites and rocket stages—particularly from large satellite constellations—inject material into Earth’s atmosphere, updating prior estimates of space waste from 2015–2025 and projecting future scenarios. To reduce collision risks in orbit, defunct satellites and rocket stages are intentionally burned up in the atmosphere, where they release a diverse mix of elements—including aluminum, lithium, fluorine, chlorine, and bromine—from their structural and functional materials. It is unclear how this material might be changing atmospheric chemistry.
The researchers combined reentry databases, detailed knowledge of satellite and rocket compositions, and ablation factors to calculate the mass injection of 43 elements, comparing it to natural meteoroid input. The goal was to assess the scale of anthropogenic metal deposition in the mesosphere and stratosphere, identify potential environmental effects (e.g., ozone depletion, radiative forcing, cloud formation), and highlight the need for further research on atmospheric accumulation and chemistry of these elements.
The team found that human space activities are now a significant source of upper-atmosphere metals, with potentially wide-ranging environmental consequences.
