The number of objects orbiting the Earth will significantly increase with the deployment of large constellations of small satellites, along with the launch infrastructure needed to support it. Upon reaching the end of service life, most satellites and upper stages of launch vehicles in low-Earth orbit (LEO) burn up during reentry in the mesosphere. This high-altitude influx of chemical species such as Aluminum, which is dominant in aerospace structures, raises questions about the long-term impacts of burning anthropogenic objects during atmospheric reentry. The polluting potential of the said activities encompasses fluctuations in radiative forcing, impacts in ice nucleation, cloud condensation, and stratospheric ozone concentrations. We present a methodology that resorts to large-scale Molecular Dynamics simulations to infer the behavior upon reentry of a typical small satellite with an Aluminum-rich structure. As a first-principle informed method for modelling physical and chemical interactions, it allows to preform simulations of increasingly larger domain sizes at atomic scale, emulating the behavior of up to hundreds of thousands of atoms to compute the oxidation yield and particle size distribution. The full-scale scenario results are inferred from the atomic scale, showing that the byproduct particle size follows a lognormal distribution centered in the nanoparticle regime (nucleation/Aitken mode).This tool can provide more accurate inputs to atmospheric models aiming at estimating the global impact of reentries from LEO in the atmosphere. The use-case is focused in the oxidation of Aluminum upon reentry, and forecasts are made and compared against the contribution from micrometeoroids entering atmosphere.
