The bandwidth requirements for communications around the planet are rapidly escalating. Besides ground-based optical fiber/cellular communications, increasing reliance is being placed on communication satellite constellations for more complete global coverage. The SpaceX Starlink, Telesat, Amazon’s Project Kuiper, and OneWeb constellations, for instance, will consist of thousands of satellites in low earth orbit (LEO) with the purpose of providing low-latency, high-speed broadband connectivity. Although the communication links will initially be via microwave, it is expected that, over time, lasercom links will predominate as microwave frequency allotments become scarce and the need for ever greater bandwidths and security increase.
With the advancements of telescope system capabilities described in this paper, these systems can be turned into lasercom ground stations, commonly known as optical ground stations (OGSs). The main OGS components consist of the telescope (optics and mount) and an optical bench that enables the system to receive and transmit data to a lasercom space terminal that is hosted on the end-user’s satellite. Since satellites with lasercom space terminals are expected to be located in different orbits from low earth orbit (LEO) to geostationary orbit (GEO), different telescope apertures can be used depending on link communication budgets.
The OGSs that are to be built and integrated with the network provider’s infrastructures are expected to operate within the Short-Wave Infrared (SWIR) waveband. Collaboration between the network providers, the space terminal supplier, and the OGS supplier are required to build a reliable communication network.
Keeping track of the rapidly increasing number of satellites and their changing orbits—SDA—will be a major challenge. Existing space surveillance networks rely on radars to track RSOs, as well as a few optical observatories designed for the acquisition of new objects. The goal is to augment existing optical and radar capabilities with these new robotic telescopes. Radar and optical can work together by utilizing radar data to queue optical systems to track RSOs and record their parameters. Using multiple low-cost telescopes with the combination of different sensors can help provide more accurate orbital parameters and also identify and characterize the RSOs.
The fast-slewing and the precise pointing and tracking capabilities of the new breed of medium-aperture production telescopes maximize the time spent on target as opposed to moving to or acquiring the targets. The relatively low cost and high reliability of these telescopes increases their cost-effectiveness. Formed into arrays and networks, they can provide assured, continuous coverage of many satellites.