Ravindra Desai, University of Warwick; James Blake, University of Warwick; Jack Bowden, Open Cosmos; Matthew Brown, University of Birmingham; Johnathan Burchill, University of Calgary; Sean Elvidge, University of Birmingham; David Fischer, Space Research Institute; Colin Forsyth, University College London; Christian Fuchs, German Aerospace Center (DLR); Gabriele Giorgi, German Aerospace Center (DLR); Igor Hoerner, University of Stuttgart; Dhiren Kataria, SWRI; Dong Lin, Clemson University; Stefan Löhle, University of Stuttgart; Werner Magnes, Space Research Institute; Cathryn Mitchell, University of Bath; Georgios Nicolau, University College London; Keiichi Ogasawara, SWRI; Lasse Klausen, University of Oslo; Evgeny Panov, Space Research Institute; Juraj Poliak, German Aerospace Center (DLR); Benjamin Rödiger, German Aerospace Center (DLR); Christopher Schmidt, German Aerospace Center (DLR); Eamon Scullion, Northumbria University; Paul Strøm, University of Warwick; Ansu Sun, Northumbria University; David Themens, University of Birmingham; Robert Watson, Clemson University; Robert Wicks, Northumbria University; Josh Wilkinson, Open Cosmos
https://doi.org/10.64861/OJTO3917
Keywords: Atmospheric variability, space weather, satellite drag, satellite laser ranging
Abstract:
The accumulation of space debris, and congestion of near-Earth orbits, represents an outstanding challenge to the safe use of our space environment. Tens of thousands of orbital debris are actively tracked by the Space Surveillance Network, while millions of 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 debris, 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, and energetic particle precipitation (EPP), 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 satellites 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 targets coordinated measurements in LEO across a range of altitudes, latitudes and longitudes to understand the evolution of field-aligned and ionospheric currents, EPP 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 provide extended in-orbit tracking of orbital perturbations and resolve meso- and micro-scale atmospheric drag dynamics._x000D_
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This ROARS mission concept to LEO is enabled by rapid developments in low-cost technology miniaturisation and represents an unprecedented opportunity to observe and predict the forces of satellite drag. This cross-cutting endeavour builds upon magnetospheric formation flying measurement concepts, to constrain how solar and geomagnetic activity modulates upper atmospheric dynamics, and utilises an extensive satellite tracking ground segment that spans radar, laser ranging and optical systems, connecting knowledge and technologies across disciplines. Two overarching themes drive this multi-point mission architecture, which is designed to facilitate model validation and data assimilation: [1] Obtain coordinated measurements of upper-atmospheric variability across multiple LEO altitudes to resolve the 3D+time structural dynamics that affect satellite drag (measure the environmental inputs), and [2] Obtain and develop the best-ever space- and ground-based measurements of the satellites’ orbital elements to quantify orbital perturbations arising from solar activity (measure the technological effects)._x000D_
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The swarm will be launched into a polar orbit near 500 km and an orbital transfer vehicle will establish their formation. Two satellites will have apogees over the north pole of 500 km and perigees of 350 km over the south pole. Two further satellites will observe across the same altitudes but possess an opposing argument of perigee, i.e. perigee over the north pole and apogee over the south pole. Two further satellites will populate a circular orbit near 425 km with the same orbital period as the eccentric orbits and two further satellites will also orbit at 425 km with a small separation in local time to the first two. This swarm configuration achieves two main aims. Firstly, the common orbital periods will result in the first radial alignments in the auroral regions, allowing three dimensional sampling of the upper thermosphere and ionosphere along connected magnetic field lines. Secondly, each point in the swarm will contribute to forming a large number of tetrahedra over the poles to provide unprecedented curlometer magnetometer capabilities for measuring field aligned currents. Within each orbit, two satellites will be distributed with along-track separations of 100 to 1000 km to sample associated spatio-temporal variabilities and allow intersatellite distance ranging measurements for in-orbit tracking of drag variability and orbital perturbations. The swarm will maintain the relative formation whilst naturally decaying in altitude to sample lower and lower regions of the atmosphere down to below 300 km._x000D_
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The satellites will each carry a comprehensive set of payloads. Each spacecraft will carry intercalibrated neutral particles instruments to measure the neutral densities responsible for atmospheric drag as well as the along-track, cross-track and vertical winds responsible for transport and atmospheric variability. Plasma payloads will similarly measure the ion densities and drifts with high cadence local electron densities and wave activity. The tetrahedral magnetic field measurements will provide curlometer measurements of field-aligned-currents and disturbances propagating along magnetic field lines. GNSS signal sampling will allow the determination of total electron content at, and in-between, each point in the swarm. The leading and trailing satellites in each orbit will contain inter-satellite communications for bidirectional ranging measurements to continuously measure changes in their relative distances and their orbital evolution due to atmospheric drag variabilities. Passive retroreflectors will be fitted to the nadir face of each spacecraft to enable precise satellite tracking from ground satellite laser ranging stations_x000D_
Date of Conference: September 15-18, 2026
Track: Atmospherics/Space Weather