The target of the NODES project is to develop an optical ground network and corresponding service to enable optical space communications as a future compliment to SSC’s existing RF ground station network service.
In this product phase, which is the first part of NODES, the focus is on system requirements assessment, system architecture and definition of concept of operations. Also, covered by the project is the definition of relevant interfaces and an investigation of laser safety regulations. Evaluation and preparation of sites are carried out, as well as defining requirements and the procurement and commissioning of the first optical ground station of the network.
The operational concept and system design of an optical service requires a different mindset to the traditional RF case. The limited downlink predictability due to the influence of clouds poses the main challenge and will require a highly dynamic scheduling system. The system must also handle large data volumes that may be downloaded in fractions over the globe, and new formulations of service level agreements are needed.
The system requirements and specifications are further challenged by a slow market adoption of optical communication space terminals for the direct-to-Earth scenario, which together with early standardization issues create challenges on ensuring interoperability.
NODES service offering of increased data rates will help solving the data bottleneck issues which will be crucial for society to fully benefit from the technology advances and data transport from space.
NODES service consists of an orchestrated global network of optical ground stations which is reliable and efficient. It provides means of data transport with increased security and immunity to electromagnetic interference and eavesdropping. Rapid establishment of the optical service can also be expected, due to the optical band being unlicensed.
The product is a turn-key service offering, where the hardware configuration is abstracted away from the customer. It includes the internal hardware, software and procedures needed for creating the final end-user service.
The narrow optical beams from space require high precision reception, which is provided by multiple coordinated subsystems in the optical ground stations (and their counterparts in space). For example, a calibration routine for the telescope assemblies; a pre-defined pointing, acquisition and tracking sequence to allow space-ground discovery; and a fast-steering loop to allow seamless fibre coupling for demodulation.
In the event of severe local atmospheric disturbances impairing the downlink, NODES can adapt and find an alternative to ultimately deliver the spacecraft data to its customer at a pick-up point.
The service is addressing LEO satellites, it is compliant with the CCSDS O3K standard and upgradeable to serve different data rates, modulation schemes, mission purposes and orbits.
The optical ground network has at its heart a Network Management Centre, to orchestrate the whole service by handling the monitor and control, scheduling, data transfer and manage the service.
A number of remote sites are connected to the network and collect the received user data from the spacecraft to the ground station. The data is then transferred and delivered to the customer via a terrestrial network controlled by the network management centre, potentially utilizing a cloud service provider.
The current activity covers the first product phase of the NODES project (NODES stage 1) to develop the system architecture, concept of operations, carry out risk assessment, market prospection, and commissioning of the first optical ground station.
MS1 system requirements review (SRR) is scheduled for October 2022. MS2 preliminary design review (PDR) will follow in Q1 2023, with MS3 phase completion review (PCR) being scheduled for Q1 2024 following factory acceptance test of the first optical ground station.
NODES stage-2 is planned to start in 2023 with a second product phase followed by a demonstration phase of the service containing two optical ground stations.
The activity started in April 2022, kicked-off in August 2022 and achieved MS1 system requirements review (SRR) in October 2022.
Work currently in progress.