Decadal Survey Response 2026: Assessing the Atmospheric Impact of Satellite Re-Entry in the Large Constellation Era

The Secure World Foundation submitted a response to the National Academies' Decadal Survey for Earth Science and Applications from Space 2028-2037 (ESAS 2028), which will set priorities for U.S. Earth observation research and missions over the coming decade. The submission addresses the atmospheric effects of spacecraft re-entry, as well as how space weather presents further uncertainties and variabilities. SWF recommends that ESAS 2028 support sustained observation and measurement of re-entry inputs to the atmosphere, alongside characterization of ablation processes, coordinated access to spacecraft composition data from operators and manufacturers, and coordination with the heliophysics community on thermospheric modelling.‍

Executive Summary‍

The Secure World Foundation works to promote the long-term sustainability of space activities. This submission highlights an emerging area for Earth system observation associated with the growth of satellite re-entry activity. In line with prevailing best practices and to minimize casualty risk on the ground, many satellites are designed for demise through atmospheric re-entry after operational lifetimes of five to seven years. During re-entry, spacecraft ablate in the upper atmosphere, releasing metallic particles and aerosols. Large commercial constellations are greatly increasing the volume of such spacecraft-derived materials being introduced into the upper atmosphere. 

Early research has shown spacecraft-derived metals to be a measurable component of stratospheric aerosol, and that anthropogenic inputs now exceed meteoritic inputs for a growing number of elements. However, their effects on atmospheric composition, chemistry, and dynamics remain poorly understood, with gaps in observation, source characterization, atmospheric transport and persistence, and the potential resultant impact on ozone chemistry.

The rate at which the materials enter the atmosphere, while primarily driven by satellite launch and disposal cycles, is subject to various uncertainties. Re-entry rate, location, and timing can depend on atmospheric density changes, which is strongly influenced by solar activity. In addition to solar extreme ultraviolet flux baselines, geomagnetic storms can further accelerate orbital decay. Solar Cycle 25 reached maximum in late 2024, the first solar maximum to coincide with the era of large satellite constellations. The next maximum, expected during the 2028-2037 decadal period, is expected to affect a substantially larger satellite population based on current growth trajectories.

Establishing sustained observation and measurement capability during this decadal period would improve understanding of both atmospheric inputs from spacecraft re-entry and the role of space weather in shaping them. We hence recommend the following actions to achieve this important outcome:

• Recognize the atmospheric effects of spacecraft re-entry as a measurement priority within the Atmosphere branch of NASA’s Earth System Science Research Program.

• Establish sustained, in-situ observation of metal and aerosol content in the stratosphere, building on existing satellite, airborne, and ground-based assets where possible.

• Support laboratory and flight characterization of ablation for representative spacecraft materials, including validation of burn-up fractions and particle size distributions.

• Facilitate coordinated access to spacecraft composition and disposal data from operators and manufacturers, under confidentiality arrangements where required.

• Ensure re-entry flux estimates used in atmospheric studies account for solar and geomagnetic variability, with prediction uncertainty carried through to the resulting atmospheric estimates.

• Coordinate with the heliophysics community so that thermospheric density models, forecasts, data, and analysis are available for use in re-entry flux estimation.