Satellite Based AIS (Automatic Identification System)

Satellite-Based AIS (Automatic Identification System)

All international ships of more than 300 tons and all passenger vessels, irrespective of size, are mandated by the International Convention for the Safety of Life at Sea to carry a transponder that broadcasts their position, course and speed as a collision avoidance system. This tracking system, called the automatic identification system (AIS), sends information to other nearby vessels so it can be displayed and utilized in conjunction with radar. AIS data is transmitted through very high frequency (VHF) radio waves, so its horizontal range has generally been limited to approximately 50 nautical miles or less. 

AIS data is used for more than just collision avoidance. Maritime authorities, recognizing the benefits of tracking a ship’s identification, location, heading, speed and cargo, have installed AIS receivers on shore that capture relevant ship information, allowing tracking of ships close to shore. The use of AIS information in congested shipping areas has become standard practice for many nations. 

However, there still exists a need to know the exact location of ships as they travel beyond the limits of the coastal AIS service. Since the introduction of AIS, the global positioning system and other technology has progressed, and several solutions have provided greater visibility of ship locations on a worldwide basis. One such initiative is an International Maritime Organization-mandated service, long-range identification and tracking (LRIT), which requires certain classes of ships engaged in international voyages to report their position every six hours using onboard communications. However, the costs and long refresh rates of LRIT make it inadequate for some uses. 

ORBCOMM Satellite AIS

In 2004, ORBCOMM negotiated with the U.S. Coast Guard to launch a concept demonstration satellite equipped with an AIS receiver. ORBCOMM also developed additional satellites with AIS receivers, and a total of six AIS-equipped satellites were launched by June 2008. With these satellites, ORBCOMM became the first commercial service provider of satellite AIS services. Licensing of the service began in late 2008. 

Satellite AIS can track ships when they are out of range of coastal AIS systems. This is because while VHF signals have a horizontal range of about 50 nautical miles, VHF signals extend much farther into space, where satellites equipped with AIS receivers can capture this information and relay it to the ground. By using existing AIS technology already installed on ships, the AIS satellite service does not require additional ship-based hardware to be installed. 

Using its terrestrial global network of 15 gateway Earth stations to receive this satellite information, ORBCOMM provides licensees with a ship’s name, position, course and speed, which can then be displayed at AIS-equipped facilities for coastal AIS, providing users with an extended view of the shipping network. When combined with shipping informational databases, a complete picture of the ship’s course and all relevant information can be displayed, tracked and recorded. The satellite AIS system allows a ship to be tracked in near real time from the time it departs a port to the time it arrives at its destination. 

Refresh rates on AIS data have been in the low single-digit hours, but it is anticipated that when all ORBCOMM satellites are deployed, the refresh rate will be less than an hour. The reason for the current slower refresh rates is because a satellite cannot upload its captured AIS information until it is above a gateway Earth station. This refresh rate will improve as more AIS-equipped satellites become operational. 

Satellite AIS will never approach the same refresh rate obtained from coastal AIS, which captures and displays all three or six second transmissions. This is not an issue, as quick refresh rates for ships in the middle of the Indian or Pacific Ocean is not a necessity. As shipping gets closer to the shore—i.e., between 50 and 120 nautical miles—the need for improved refresh rates becomes increasingly important, which satellite AIS can provide. 

AIS information is collected by ORBCOMM satellites. These satellites relay this data to Earth once above a Gateway Earth Station, where data can be sent to customers.

Vessel Management

Port authorities were some of the first to identify the benefit of the satellite AIS service. The Port of Rotterdam in the Netherlands quickly took advantage of the new global AIS information. Data, including ORBCOMM satellite AIS information, are supplied to port officials via ORBCOMM partner LuxSpace Sarl (Betzdorf, Luxembourg) and Royal Dirkzwager (Maassluis, Netherlands). 

The Rotterdam system provides near-real-time data on all ships bound for the port and requires no intervention, providing a clear global picture of incoming traffic. The system also tells port authorities about incoming cargo and an estimated arrival time so they can gather the necessary resources for rapid unloading of the cargo, which maximizes productivity of the berth facility. For shipowners, the ability to dock quickly, unload and sail in a short time provides improved utilization of capacity and can improve revenue. 

Satellite AIS by itself will not provide the sophistication that is needed to manage the activity of a port. When combined with other vessel and port management tools, however, satellite AIS provides a much broader picture of ship traffic and port loading. It can also make the port authority quickly aware of delays caused by weather, malfunctions and other unforeseen incidents so it can plan accordingly. 

Search-and-Rescue Applications

As more AIS-equipped satellites come online, AIS information will continue to grow in importance as a powerful aid in search and rescue, environmental incidents and maritime domain awareness. 

When dealing with search and rescue, it has become apparent that the most important use of satellite AIS is to determine what ships are closest to the vessel or incident. Vessels today are equipped with beacons that transmit a distress signal. However, especially in the Pacific and Indian oceans, a vessel in distress can be thousands of nautical miles from the nearest search-and-rescue organization. Satellite AIS can provide an immediate picture of all shipping close to the distressed vessel, allowing search-and-rescue authorities to contact these vessels and direct them to provide assistance. 

This functionality proved to be useful for a search-and-rescue effort offshore Australia. By using satellite AIS, responders were able to determine the closest vessel to a yacht sinking in the middle of the Indian Ocean. Rescue workers contacted nearby ships, which changed course and rescued two sailors from the sinking sailboat. 

Environmental and Security Applications

Satellite AIS can also play a role in identifying suspected polluters. If pollution is found, satellite AIS can identify all ships traversing the area. With this information, maritime authorities can then follow to identify the “DNA” of the ship and determine which vessel was responsible for the pollution. 

The use of satellite AIS for security and monitoring is particularly advantageous in areas where coastal AIS is not economical. Examples of this would be in the Arctic around such countries as Canada, where the installation and operation of coastal AIS becomes cost-prohibitive. In addition, countries generally have limited resources in the Arctic regions and satellite AIS will give them some ability to identify ships traveling through Arctic waters. 

Additional Satellites and Conclusions

Satellite AIS is a continuous service that will steadily improve toward a more rapid refresh rate. ORBCOMM intends to launch four satellites in 2011 (August 18 they have launched 2 at the same time). During the following two years, ORBCOMM intends to launch a further 16 satellites. 

ORBCOMM’s experience over the last two years has shown that increasing the number of satellites and ground stations improves the refresh rate on the AIS display and the information provided. The move to the constant flow of shipping data will aid the maritime world and will give it a more real-time picture of shipping around the world. With more than 60,000 large ships equipped with AIS transponders, it is now possible to know where practically all ships are, where they are going and when they will get there. 

James Webb Space Telescope

Even while construction of the James Webb Space Telescope is underway on the most advanced infrared vision of any space observatory, its technologies are already proving useful to human eye health here on Earth. "The Webb telescope program has enabled a number of improvements in measurement technology for astronomy, mirror fabrication, and measurement of human eyes, diagnosis of ocular diseases and potentially improved surgery," said Dr. Dan Neal, Research Fellow at Abbott Medical Optics Inc. in Albuquerque, N.M. 

The Webb telescope will be the most scientifically powerful telescope NASA has ever built - 100 times more powerful than the Hubble Space Telescope. The Webb telescope will find the first galaxies that formed in the early universe. It will also peer through dusty clouds to see stars and planets being born, connecting star formation in our own galaxy with the solar system. "The advanced wavefront sensing technology developed for testing the Webb telescope's 18 primary mirrors led to the new applications in other areas," said Tony Hull of L3 Integrated Optical Systems Division-Tinsley Facility in Richmond, Calif., where the Webb's mirrors were recently polished to accuracies of less than one millionth of an inch. 

"Wavefront sensing" is used to measure shape of the mirrors during fabrication and control the optics once the telescope is in orbit. Ophthalmologists routinely use wavefront technology to measure aberrations of the eye. Those measurements help with diagnosis, research, characterization and planning treatment of eye health issues. "The technology also provides more accurate eye measurements for people about to undergo Laser Refractive Surgery," Neal said. "To date 10-12 million eyes have been treated with Lasik procedures in the U.S. alone. As technology improves, so does the quality of these procedures." 

A new "scanning and stitching" technology developed for the Webb telescope led to a number of innovative instrument concepts for more accurate measurement for contact lenses and intra-ocular lenses. Another benefit to eye health is that this technique can help "map" the topography of the eye more accurately. Think of the surface of your eye as being as dented as the surface of the moon. Precise measurements of your eye's surface are helpful when assessing eyes for contact lenses. The scanning and stitching technology improvements have enabled eye doctors to get much more detailed information about the shape and "topography" of your eye, and do it in seconds rather than hours. 

Four patents have been issued as result of innovations driven by the Webb telescope program. "These tools are now used to align and build the next generation of measuring devices for human eyes," Neal said. "The lasting impact of the Webb telescope may go beyond the vision of astronomers seeking to see the distant universe; the impact may be a better national technology base and better vision for people everywhere," Hull said.