Space waste: An update of the anthropogenic matter injection into Earth atmosphere

TL;DR

This paper updates estimates of anthropogenic space waste injection into Earth's atmosphere from 2015 to 2025, highlighting a significant increase in metal elements that may impact atmospheric chemistry and climate.

Contribution

It provides a detailed comparison of space waste element fluxes with meteoric injection, considering 43 elements and future scenarios up to 2025.

Findings

Strong rise in space waste mass influx since 2020

Dominance of transition metals in recent injections

Potential long-term atmospheric effects such as ozone depletion

Abstract

Large satellite constellations are one of the main reasons for an increasing amount of mass being brought into low Earth orbit in recent years. After end of life, the satellites, as well as rocket stages, reenter Earth's atmosphere. This space waste burns up and thus injects a substantial amount of its matter into the mesosphere and lower thermosphere. A first comprehensive analysis of the anthropogenic injection and a comparison to the natural injection by meteoroids was presented by Schulz & Glassmeier (2021). They found significant and even the dominant injection of several metal elements regularly used in spacecraft compared to the natural injection. The first observations of space waste remnants in stratospheric aerosol particles (Murphy et al., 2023) confirmed several of these estimates, but also revealed differences and new insights. The current study presents an update to the space waste injection estimates of Schulz & Glassmeier (2021), assessing the years from 2015 to 2025 but also considering future mass influx scenarios. 43 elements are considered and thus a much more detailed comparison to the meteoric injection is possible. Comparison of estimated elemental fluxes to stratospheric aerosol data shows excellent agreement. From 2020 onward, a strong rise in space waste mass influx to the atmosphere can be seen. Future scenarios discussed by Schulz & Glassmeier (2021) may already be reached by the end of 2025. In 2024, 24 elements were dominating the meteoric injection compared to 18 in 2015. Several of them are transition metals, which are known for their catalytic activity. This indicates a substantial risk of long-term adverse effects on the atmosphere such as ozone depletion, radiative effects and changes in cloud formation, if no action is taken. Research is urgently needed into the atmospheric accumulation, chemistry, and general atmospheric effects of specific elements.