New Zealand’s contribution to free-space optical communications (FSOC) is centred on the **Taiaho Observatory**, a prototype FSOC ground station established at Ardmore by the University of Auckland. Developed under a Catalyst:Strategic partnership with the German Aerospace Center (DLR), Taiaho serves as the first operational New Zealand node in the **Australasian Optical Ground Station Network (AOGSN)**. The observatory is equipped with a 12″ Ritchey–Chrétien telescope on a direct-drive mount, integrated with a DLR-designed SOFA optical communications terminal. First light was achieved in early 2024, and the first successful satellite laser downlink—received from DLR’s *Flying Laptop*—occurred on 14 February 2025.

Taiaho’s development is closely aligned with AOGSN’s broader objectives: enabling high-bandwidth optical links to LEO and GEO satellites across a distributed network of geographically diverse stations. Cloud cover analysis has shown that New Zealand sites contribute significantly to network reliability, reducing total outage probability when paired with Australian nodes. The observatory is designed for autonomous operation, incorporating real-time environmental sensing, automated tracking, and pass scheduling software that coordinates with satellite ephemerides and weather forecasts. It also contributes to collaborative activities with DLR and Australian institutions on optical data routing, site diversity modelling, and future quantum communication capabilities.

To support this FSOC infrastructure, a dedicated atmospheric turbulence characterisation programme has been established. Accurate knowledge of atmospheric seeing and turbulence structure is essential for optimising link budgets, predicting performance, and enabling adaptive optics correction. Three complementary systems are being used for this purpose.

A **Differential Image Motion Monitor (DIMM)** provides continuous seeing measurements at the observing site, offering baseline estimates of integrated turbulence strength. A second system, the **Ring-Image Next Generation Scintillation Sensor (RINGSS)**, developed by Tokovinin and collaborators, is used to retrieve vertical turbulence profiles by analysing ring-shaped stellar images.

The third instrument is a **scintillometer system based on a DLR design**, measuring fluctuations in the refractive index along horizontal and slant paths. This adds sensitivity to low-altitude turbulence layers that can strongly affect FSOC performance, especially for terminals near sea level.

Together, these instruments allow detailed site assessments across multiple candidate locations in New Zealand—including Ardmore, Mt John, Lauder, and Warkworth. By combining FSOC terminal development with comprehensive atmospheric monitoring, the Taiaho programme positions New Zealand as a strategic partner in future optical satellite communication networks, including high-speed data relay and quantum key distribution missions.

Rattenbury, N., et al., 2025, Update on the German and Australasian Optical Ground Station Networks, Volume43, Issue3, Special Issue on Advances in Optical Space Communications, International Journal of Satellite Communications and Networking