The Impacts on Terrestrial Astronomy from Very Low Earth Orbit Telecommunications Constellations

Ian Muirhead*, Peter Roberts, Nicholas H. Crisp, Ciara Mcgrath

*Corresponding author for this work

Research output: Contribution to conferencePaper

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Abstract

This presented work assesses the potential benefits to terrestrial astronomy through the deployment of telecommunications spacecraft into lower orbits. Results show that by operating closer to the user in Very Low Earth Orbits (VLEO) the illumination of a constellation rapidly reduces and the scientifically useful operational time at key locations is greatly increased.
In recent years the exponential growth in Low Earth Orbit (LEO) constellations has caused concern to the astronomical community, primarily due to the increase in broadband internet provision through the Starlink satellite network. A range of novel services are being enabled by these constellations to great public benefit and of future commercial interest is the extension of terrestrial mobile capabilities through non-terrestrial networks delivering direct-to-device connectivity to low power handsets. Some current delivery plans rely on large surface area phased arrays such as the BlueWalker3 prototype. This deployed a 64 square metre antenna at an orbit of 510 km and was observed at a 0.4 peak V-band apparent magnitude, making it one of the brightest night sky objects and impacting terrestrial observations when transiting the field of view. This is a precursor to a 243-spacecraft constellation at 725 – 740 km that may increase in brightness and display longer periods of visibility.
A possible mitigation against these astronomical impacts may be obtained by operating constellations in VLEO. Developments in erosion resistant and drag reducing materials, along with advances in traditional and atmosphere breathing electric propulsion have begun to open this orbital regime and current applications have generally focused on Earth Observation (EO). However, reductions in power and latency due to shorter transmission distances, access to higher frequencies and data rates from reduced path loss, and eased demands on spacecraft components due to the benign radiation environment all present opportunities in the delivery of high speed, low latency, ubiquitous global telecommunications and may be particularly beneficial for direct-to-device services.
This paper describes analytical models representing constellations across a range of altitudes and compares the impact on the operational performance of optical astronomy facilities at three representative locations. Analysis shows that lower constellations maximise the satellite free observational time during astronomical night with only a 0.3 - 4.6% loss due to a satellite constellation orbiting at 250 km with the greatest benefit at lower latitudes, compared to 21.4 - 35% degradation at 550 km and 56.5 - 67.2% of fully operational observation time impacted at an altitude of 1150 km.
Original languageEnglish
Pages1-10
Number of pages10
Publication statusSubmitted - 8 Oct 2024
Event75th International Astronautical Congress (IAC): Responsible Space for Sustainabilty - Milan, Italy
Duration: 14 Oct 202418 Oct 2024

Conference

Conference75th International Astronautical Congress (IAC)
Abbreviated titleIAC2024
Country/TerritoryItaly
CityMilan
Period14/10/2418/10/24

Keywords

  • Very low Earth orbit (VLEO)
  • Dark and Quiet Skies
  • Satellite constellation

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