Atmospheric Composition in the Constellation Era – The AC2E Initiative (2027 – 2037)

Why AC²E?

The AC²E initiative is based on several comments from scientists working in the MLT region regarding the potential impact from re-entering space debris burning up in the mesosphere. Furthermore, increasing numbers of orbital launches might have exhaust effects on the MLT region.

The initiative will focus on the possible impacts caused by the emerging large constellations of satellites. Hence, it’s of vital importance to start a monitoring program as early as possible to secure baseline data before too many constellations are in orbit and the re-entering mass increases exponentially.

The mesosphere is sometimes referred to as the "new ocean" since in earlier times, people considered items dropped into the ocean as something they didn’t need to worry about anymore. It “disappeared”. These days we know much better.

Only in January 2025, 120 Starlink satellites burnt in the atmosphere. According to an ESA report, in 2022, more than 200 tons of metal particles were introduced into the atmosphere, in 2024, it was already 800 tons. Until 2040, more than 60.000 new satellites are predicted to be launched into orbit. This might lead to the disposal of up to 10.000 tons of Al₂O₃ / year into the atmosphere. Especially the upper atmosphere is very vulnerable for two reasons. Due to its low density, mass contribution has a much bigger effect. 1 ton of material in the MLT region equals up to 100.000 tons in the troposphere.

What is AC²E?

 The “AC²E” is an international collaboration effort targeting advancement in specific, fundamental issues in space and earth science. The concept was conceived and developed between 2024 and 2026 by Andøya Space (ASP), Esrange/SSC and DLR MORABA.

The main aim for AC²E is to set up a repetitive monitoring program providing measurements in the Mesosphere / Lower Thermosphere (M/LT) at regular intervals by any means possible, but in a systematic and standardized way. Thus, providing regulatory bodies with relevant background information for decision making.

The projected timeframe of 2027 to 2037 is specifically chosen to align the initiative with the upcoming Solar Cycles 26 and 27, which have a large influence on the dimensions and characteristics of Earth’s atmosphere and its interaction with space objects. Such background information must be based on as much pristine and unmodified data as possible.

Possible science topics

 Atmospheric Pollution from Re-entry: As satellites demise, they burn up and release materials (e.g., aluminum, titanium, composites) into the MLT. Sounding rockets equipped with sensitive instruments can:

·           Identify and quantify new types of artificial aerosol layers resulting from satellite re-entry.

·           Investigate the chemical reactions of these materials with the ambient atmospheric constituents.

·           Assess the potential impact on natural metal layers and MLT chemistry, including ozone.

Influence on NLCs/PMCs

Localized Atmospheric Perturbations

Impacts of Orbital Rocket Launches