The Automatic Identification System (AIS) is a short-range coastal tracking system currently used on ships. It was developed to provide identification and positioning information to both vessels and shore stations. Ships of 300 gross tonnage or more sailing on international voyages, cargo ships of 500 gross tonnage or more sailing in local waters, and all passenger ships irrespective of size are mandated by the International Maritime Organization (IMO) to carry AIS equipment. AIS transponders automatically broadcast information at regular intervals. Navigational status data is transmitted every 2 to 180 seconds, depending on a vessel's activity. In addition, voyage related data is broadcast every 6 minutes. These signals are received by AIS transponders installed on other ships or by land-based systems.
The AIS signals have a horizontal range of about 40 nautical miles (74 km), meaning that AIS traffic information is only available around coastal zones or in a ship-to-ship zone. AIS communication takes place using two VHF frequencies, 161.975 MHz and 162.025 MHz, using a bandwidth of 25 kHz. Although only one radio channel is necessary, each station transmits and receives over two radio channels to avoid interference problems, and to allow channels to be shifted among ships without communications loss.
What is SAT-AIS?
Space-based AIS (SAT-AIS) will make it possible to track seafaring vessels beyond coastal areas that are equipped with AIS tracking devices. SAT AIS is a promising solution to overcome terrestrial coverage limitations with the potential to provide AIS service for any given area on Earth.
ESA is promoting a European-based SAT-AIS system in partnership with the European Maritime Safety Agency (EMSA).
What is EMSA?
EMSA is a European regulatory agency established in the late 1990s along with a number of other major European maritime safety initiatives. It supports the European Commission and the Member States in the field of maritime safety services, e.g. prevention of pollution from ships. Subsequent amendments have refined and enlarged its mandate.
EMSA is currently tasked with assisting the European Commission in monitoring the implementation of EU legislation relating to, among others, ship construction and planned maintenance, ship inspection and the reception of ship waste in EU ports, certification of marine equipment, ship security and the training of seafarers in non-EU countries. EMSA is also instrumental in EU-level support programmes, such as the SafeSeaNet (SSN) system, which uses AIS to track vessels and hazardous cargoes, and the EU LRIT Data Centre, to ensure the identification and tracking of EU-flagged ships worldwide.
SAT-AIS will greatly increase the coverage and effectiveness of programmes such as SafeSeaNet.
Who will use SAT-AIS?
The following groups of users have been identified:
- Maritime Security services: support of security operations
- Law-enforcement services: anti-piracy, illegal fishing, enforcement of international/ national regulations, support of enforcement operations
- Search and Rescue (SAR) services
- Maritime surveillance services: monitoring of vessels in sensitive areas, anti-drug smuggling, border control
- Environmental services: hazardous cargos monitoring, prevention of pollution caused by ships, pollution response
- Maritime Safety services: vessel traffic/navigation monitoring, vessel traffic management, support of safety operations
- Fleet management services for commercial users (shipping companies and ship owners)
ESA’s SAT-AIS Initiative
SAT-AIS is being developed through three ESA ARTES programme elements:
- ARTES 5 – Specific technology predevelopment activities, including antenna miniaturisation, receiver developments, and a performance testbed in the form of an end-to-end simulator.
- ARTES 20 – Implementation and validation of a Data Processing Centre as “space node” in close cooperation with and co-funding from EMSA for full data integration into SafeSeaNet services.
- ARTES 21 phase 1 – Initial steps of the system design and implementation, including estimating the economic potential by means of a cost-benefit analysis of an Operational Demonstration Mission (ODEM), system design studies, comparative performance assessments, as well the exploration of a possible Public Private Partnership (PPP) implementation scheme for the European SAT-AIS operational system.
- ARTES 21 phase 2 – covers the detailed design and implementation of the SAT-AIS microsatellites and payloads, and the development of innovative SAT-AIS applications and services. Following the system definition and trade-off analysis carried out in preliminary studies, a constellation of so-called microsatellites has been retained as the most cost-effective solution for providing SAT-AIS services and maintaining its viability. For this commercially-oriented project, called E-SAIL, LuxSpace will be the industrial prime contractor. In parallel, ESA is developing also a SAT-AIS payload for the forthcoming Norwegian NORSAT-1 mission, which will also fly two additional scientific payloads. Kongsberg Seatex is the prime contractor responsible for defining the technical system requirements, the development, manufacturing, assembly, test and qualification of the Novel SAT-AIS Receiver, NAIS. The operator of the NORSAT-1 satellite will be the Norwegian Space Centre (NSC). NSC will be responsible for the top-level mission requirements.
What was achieved during the first phase of ESA's SAT-AIS initiative?
The first phase of the initiative (2011 – 2013) encompassed system design activities and technology pre-developments. These included:
- Advanced algorithm patented by ESA
- Receiver and algorithm developments
- Antenna miniaturization development
- SAT-AIS testbed
- Comparative Performance Assessment, performing blind-testing of proposed solutions
- System Design Element: Two parallel design studies addressing the architectural trade-off and the SAT-AIS system design with the objective of consolidating the SAT-AIS system requirements.
- Data Processing Centre collecting SAT-AIS messages, ancillary and auxiliary information for generating and distributing enhanced data services to the maritime community.
- Demonstration projects using SAT-AIS for areas of interest, e.g. support to the EMSA Blue Belt project.
- Private Public Partnership models, including business model evaluation for solutions integrating private and public SAT-AIS assets.
In addition, the AIS standard as defined in ITU-R M.1371 was originally devised for transmissions from ships to coastal stations. The detection of the AIS signals from the satellite faces technical challenges that were not considered in the original AIS standard, for example colliding messages from ships transmitting from different SOTDMA cells and lower signal to noise ratios. These issues required particular care and ESA initiated and conducted internal and external activities with the objective to improve the technology and system concepts. One of the outcomes of these activities is the ESA-proposed patent, “Advanced Receiver Design for SAT-AIS Detection” which, in combination with an advanced antenna concept, can significantly improve vessel detection in high-traffic zones.
What is planned for the second phase?
During the second phase (2013 – 2019), innovative SAT-AIS microsatellites and payloads will be developed and launched on a PPP-like basis, and new applications and services will be created.
The various implementation projects of the second phase include:
- The Novel SAT-AIS Receiver — This concerns the development of a third generation Novel SAT-AIS Receiver (NAIS), mainly focusing on low power consumption, small size and advanced signal processing for nano- and microsatellites. It will encompass the design, development, manufacturing, assembling, testing, and qualifying the SAT-AIS receiver as suitable for nano- and micro satellites. The Norwegian Space Center will be the satellite operator and is responsible for the integration of the new receiver into the national NORSAT-1 satellite, as well as launch and operation of the satellite.
- Micro-satellites (E-SAIL) — This concerns the development of SAT-AIS micro-satellites, focusing on step-wise evolution of the next generation of these spacecraft towards improved SAT-AIS performance with extended antenna and raw data handling capabilities. This will encompass the design, development, manufacture, assembling, testing, and qualification of several innovative SAT-AIS micro-satellites. These will be targeted at different price/performance points for the commercial AIS market.
- Plasma — This concerns the design, development and pre-operation of a service framework that will provide SAT-AIS data value-added information services to institutional end-users and commercial companies. It will collect AIS messages from terrestrial and space based sources, validate and process them to generate: validated/enhanced SAT-AIS messages enriched with metadata on AIS messages correctness, and warnings of suspicious or anomalous vessels behaviour. The platform will be designed and developed in close cooperation with the end-users involved in the project (i.e., EMSA, SAMSA and BlueFinger), and eventually demonstrated to them during the demonstration period with the objectives to (i) gather feedback to further fine-tune the service, and (ii) to facilitate users take-up of the developed service offer following the completion of the project.
These co-funded activities include all necessary prototypes and models required to qualify the latest technologies and cost-effective design based on ruggedized off-the-shelf elements.
Regarding the applications and services, the second phase ARTES 21 also includes the design, development, integration, deployment, running and validation of new applications and services which make use of satellite-based AIS data and possibly additional data associated with individual AIS messages (e.g. Doppler shift measurements, timestamps, power levels, etc.).