Authors
Samuel Thé, Frank D. Lind, Daniel Sheen, and Aleks Pop Stefanija
Abstract
Many stakeholders are currently interested in space-based telecommunication services and mega-constellations of satellites in low-Earth orbits (LEO) are becoming very common. These satellites can greatly improve connectivity in remote regions, via service specific antennas or even transmission directly to customers’ cell phones. However, remote places are also where most radio telescopes are located, ideally isolating their sensitive instruments to man-made radio interference (RFI). The increasing number of satellites in orbit exposes these locations to potential RFI, as the signals from astronomical objects are generally many orders of magnitude fainter than those required for communication. Both intentional and unintentional satellite emissions are challenges that the scientific community must address to co-exist with a growing need for satellite services that provide global connectivity. Multiple co-existence approaches are being tested by the community, including beam-avoidance and dynamic zone management. These methods essentially turn off or avoid illumination of radio telescopes when satellites are transiting through the boresight of the telescope. Sidelobes to sidelobes interactions between a telescope and multiple satellites are however inevitable. In this work, we present our recent results on both the observations of LEO satellites and the modeling of their effects on our measurements with the 18.3m Westford telescope of the MIT Haystack Observatory. We focus our efforts principally on joint observations of protected bands for astronomy and satellites in-band downlinks. We also extend our observation model to account for the aggregated effects of sidelobes interactions on the resulting observed RF power levels.