The accumulation of space debris, and congestion of near-Earth orbits, represent an outstanding challenge to the safe use of our space environment. Over 27,000 pieces of orbital debris are actively tracked by the Space Surveillance Network, while over 170 million smaller pieces that cannot be tracked, also pose catastrophic collision risks. Satellite drag from the Earth’s upper atmosphere is a primary perturbative force on near-Earth orbiting satellites, and its accurate characterisation is essential to predicting and preventing further collisions and the run-away proliferation of space debris.
Atmospheric drag in Low Earth Orbit (LEO) is highly sensitive to solar activity and the solar wind-magnetosphere interaction. Magnetospheric current systems close through the ionosphere and associated ion-neutral collisions, i.e. Joule heating, can drastically modulate the spatially- and temporally-varying outer extent of the atmosphere. Unlike the many isolated in-situ measurements carried out by space missions so far, distributed neutral, plasma and magnetic field observations by a swarm of CubeSats across LEO, in tandem with precise tracking of their orbital dynamics, offer the global view necessary to disentangle the influence of the coupled magnetosphere-ionosphere-thermosphere system on satellite orbits. This novel mission architecture will obtain the first coordinated measurements in LEO across a range of altitudes, latitudes and longitudes to understand the evolution of field-aligned and ionospheric currents, Joule heating and the response of the neutral atmosphere. Coordinated orbit- and ground-based space surveillance and tracking campaigns (GNSS, laser, optical) will simultaneously relate the CubeSats’ orbital dynamics to the in-situ measurements, whilst laser inter-satellite-links will resolve meso- and micro-scale atmospheric drag variabilities.
