AUSTRALIA IN SPACE
the telescope to compensate, creating a clearer image. The same technique applied to telescopes used as laser receivers will allow laser communications to achieve a reliable link through the turbulent atmosphere.
The Western Australian Optical Ground Station In the Astrophotonics research group at the University of Western Australia (UWA), we are working to translate adaptive optics and other astronomy technologies to enable reliable space-to-ground laser links, and achieve high-speed laser communications to spacecraft around Earth, the Moon, and beyond. We have been testing these technologies using smallscale optical terminals, and have achieved world-record stability of a high-precision laser signal bounced between buildings. (Because the atmosphere quickly gets thinner with increasing altitude, a horizontal link near the ground of only a few kilometres has the same amount of turbulence as a link all the way from the ground to space.) We are now working on demonstrating stable laser and data links to moving airborne targets, which is much harder than targeting a building that does not move. In August 2021, we installed a 0.7 m robotic telescope on the roof of the UWA physics building. This telescope is the core of the Western Australian Optical Ground Station (WAOGS), the first laser communications ground station in the southern hemisphere. Since then, we have been working hard to commission the WAOGS, which involves programming it to track satellites by first slewing to their predicted orbital position, homing in on them using computer vision, and then locking onto the narrow laser beam using adaptive optics. Currently, we are testing the complete integration and effectiveness of the systems by establishing robust laser links to a drone making simulated satellite passes, and measuring the stability and data transfer performance of the link. Following these tests, we aim to receive our first transmissions from a laser-equipped satellite in low Earth orbit early next year.
An Australian Optical Ground Station Network The WAOGS is the first of a larger Australasian Optical Ground Station Network (AOGSN), which will eventually comprise four ground station in Western Australia, South Australia, the ACT, and New Zealand. The stations will work together to “handover” a satellite from one to another as it passes over Australia, increasing the opportunity to downlink valuable data. Having multiple ground stations also provides resilience against adverse weather. Thanks to Australasia’s generally clear skies, if one or more of the stations are obscured by cloud, the AOGSN will still be able to establish a link to a satellite more than 90% of the time. The AOGSN will be used to test and develop advanced laser communications, and promises to benefit telecommunications in all areas of Australia, for example, by providing higher bandwidths to regional and remote areas, and providing greater reliability for disaster and emergency response.
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