The objective of the ARTES-10 AVISAT mission was to propose a satellite communication system to SESAR compatible with mandatory ICAO provisions, that best answers the user requirements and end-to-end concept of operations, and ultimately to include this satellite communication infrastructure in the SESAR ATM Master Plan. The purpose of the of the Analysis and Definition of the Satellite System Study was to provide ESA and the SESAR JU a thorough analysis of satellite communications options for ATM, and furthermore to identify the necessary subset of the overall system to support qualification of the service if accepted.
An overall objective of the study was to provide a design able to support the technical and operational requirements at the least possible cost for the airspace users which can be operated by a certified CSP.
Finally, the Phase-A was intended to provide preliminary data to support the preparation of a programme proposal for Phase II at the Ministerial Conference 2008.
The satellite system studied shall provide point-to-point and broadcast voice and data communications services for ATC and AOC. The challenges of designing such a system arise from some specifics of the ATM context. The main difficulty is seen in satisfying the two most important, but competing, requirements, namely to achieve the high reliability required for a safety-of-life service while at the same time assuring low costs.
Satellite communications are being used today in ATM for both voice and data communications. Therefore, the question of why a new system has to be studied arises. This need comes from the following considerations:
- The operational concept of ATM will change substantially. This implies new requirements for the air/ground communications infrastructure. It is against these new requirements that the options examined in the present study need to be compared.
- The satellite communications solutions used in ATM to date are reported to be not entirely satisfactory. The issues raised include the cost, dimensions and weight of the on-board equipment and the difficulties to install it on board of aircraft, the amount of the service fees. Not all these issues are necessarily of technical origin.
The European Union is moving towards implementation of the Single European Sky ATM Research (SESAR) project for implementing a new Air Traffic Management administrative, operational and technical concept. Satellite communications for Air/Ground communications (i.e. voice and data exchange between aircraft and flight control centres) have an important role to play in the future ATM infrastructure, both in Europe and in the rest of the world. In coordination with the EC, Eurocontrol, ANSP?s and the SESAR consortium, the ARTES 10 Programme intends to define and develop the use of Satcom for ATM communications in the future ATM system defined by SESAR.
Proposed Architecture of Satellite Based Communications for ATM
The study started with an investigation of the overall satellite constellation topology. The requirement to provide coverage over northern (polar) latitudes, beyond the reach of GEO coverage considered the use of HEO, LEO and MEO constellations, including dedicated satellites, shared platforms, or the use of future/existing 3rd party satellite systems for ATM.
Given the low number of aircraft currently flying polar routes compared with the high traffic density over the core ECAC region, the cost-benefit trade-off showed that a dedicated HEO, LEO or MEO system was not sustainable. The focus of the study was thence on the requirements for the core GEO component, but considered the impact on the baseline GEO system of being compatible with future/existing 3rd party LEO/MEO/HEO systems capable of covering northern latitudes.
The GEO space segment could be one or a combination of the following:
- Use of existing GEO satellites, as compatibility with existing systems is seen as a key requirement,
- Dedicated Payload,
- Dedicated Satellite with/without an ancillary payloads on-board.
High redundancy at all levels of the space segment, ground control and user segment was required. The system trade-off was performed on the basis of providing the best solution for the airspace user.
Different payload options were presented, including consideration of a smaller low capacity payload for initial operations.
The three main tasks within the Analysis and Definition of the Satellite System were:
- Space Segment System Requirements,
- Space Segment System Preliminary Design,
- Preparation of Future Work.
The project Final Review has been completed, and the project finalised. The following is a brief summary of the work stages:
The Astrium Services consortium kicked-off the Artes-10 “AVISAT” - Analysis and Definition of the Satellite System (Phase A). The WP1000 was presented at the SSRR Meeting at ESTEC including:
- The baseline system architecture,
- Input to refine the Iris System Requirement Document,
- The Operational Concept for satellite communications in ATM,
- Ancillary payloads that could be supported on the satellite.
The WP2000 – Space Segment Preliminary Design work was presented at the PDR at ESTEC. WP2000 focused on the ATM payload design and the overall system design of the GEO component including the end-to-end concept, deployment, technology roadmap, validation and the ESA funded “subset” of the system needed for validation and initial operations.
The two Communication Design Studies (Phoenix and ICOS) produced two alternative inputs for the ATM Payload Design. The System Requirement Document (SRD) assumptions that the satellite component of the future “dual-link” defined in SESAR should be able to support all ATC and AOC traffic, and that all aircraft would use Low Gain Antenna terminals to minimise end-user’s costs led to a high power requirement, resulted in a large satellite with high power and large antenna.
Several payload options were designed including preliminary cost estimations:
- A payload with multiple spot-beams covering ECAC and the global region visible from the satellite,
- A payload with fewer ECAC spot-beams avoiding spot-beam handover requirements, but needing higher power in ECAC,
- A payload only supporting the traffic in ECAC,
- A reduced capacity payload serving ECAC only, intended to fit on a smaller platform.
In addition, the integration with existing satellite networks was investigated as an option to reduce costs for the programme and for the end-user. The feasibility, commercial impact, and any drawbacks in performance compared with a dedicated system are recommended as the subject of a detailed analysis for future study.
WP3000 – Preparation of Future Work was presented at the Final Review meeting at ESTEC.
A further design option looked at better frequency re-use for the fully operational system beyond 2025. In addition the optimum service model, the system certification for safety of life services, the risk and reliability assessments, and the business case were presented