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

TL;DR

The paper addresses the atmospheric impact of anthropogenic space-waste reentry by updating injection estimates for 43 elements from 2015–2025 and exploring future mass-flux scenarios. It advances the prior work by integrating diverse data sources to model mass influx, detailed satellite/upper-stage compositions, and ablation fractions, enabling a granular element-by-element injection assessment. The findings show a pronounced rise in space-waste mass entering the atmosphere since 2020, with aluminum and several transition metals dominating the injected mass and potentially altering atmospheric chemistry, ozone processing, and cloud nucleation. Although the total injected mass remains smaller than natural meteoric input, the higher metal content and catalytic potential of space-waste materials underscore significant environmental concerns and the urgent need for atmospheric-chemistry studies and policy actions to mitigate impacts.

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.

Figures (3)

• Figure 1: Annual mass influx to the top of the atmosphere, with differentiation of object type. The gray bar shows the mass influx expected for the rest of 2025 when extrapolating the current numbers (until July 16th 2025) to the end of year.
• Figure 2: Variation of the annual mass influx to the top of the atmosphere with the object mass. The object mass is binned into mass decades. Three different mass influxes are shown: The gray bars depict the annual meteoric mass influx using values from art_Schulz_2021, which is the mean model by art_Drolshagen_2017. The middle bar shows the space waste mass influx in 2020, the right bar for 2024, both broken down by object type. Clearly, the space waste influx consists of large objects compared to the meteoric influx.
• Figure 3: Annual space waste mass influx to the top of the atmosphere and the fraction of that, which ablated in the atmosphere (hatched area). For 2025, an extrapolation for the rest of the year (after July 15th 2025) is shown in the lighter gray, again with the hatched area representing the ablated mass. All mass not ablated reaches Earth's surface.