Viability of mega-constellations as an alternative to dedicated future gravity missions

We explore an alternative approach to future gravity missions: the potential of mega-constellations, such as Starlink, OneWeb, Telesat, etc., for time-variable gravity field recovery. These constellations consist of numerous satellites in various planes and across a range of elevation and inclination bands, including very low Earth orbit (VLEO). As a result, they provide increased spatial coverage, lower revisit times, and alternate geometries (near-polar or inclined). This enables better sampling with minimal spatio-temporal aliasing and lower latency, potentially providing daily or hourly solutions of the time-variable gravity field.

A reduced-scale closed-loop simulation approach, implemented using an in-house, under-development research tool in Julia, is used to simulate multiple scenarios. High-low satellite-to-satellite tracking (hl-sst) is used for gravity recovery and will later be modified to include inter-satellite communication links (ISL) for inter-satellite ranging. Such constellations are designed for high-speed internet connectivity or for earth observation, not specifically for gravity recovery. Therefore, understanding the impact of sensor noise characteristics is critical, evaluating the trade-off between an increased number of satellites but with slightly lower instrumentation quality (compared to a dedicated mission). In addition to this, other challenges include (i) investigating new approaches for time-aware parameterisation schemes, and (ii) exploring the idea of so-called “opportunistic mapping”, i.e. to map events like tsunamis or earthquakes as and when they occur. Future research will address these questions in more detail.