these issues through the development of new technologies and over the coming years the current restriction of satellite AIS systems to Class A messages is likely to dramatically improve with the addition of Class B and Identifier messages. The fundamental challenge for AIS satellite operators is the ability to receive very large numbers of AIS messages simultaneously from a satellite's large reception footprint. There is an inherent issue within the AIS standard; the TDMA radio access scheme defined in the AIS standard creates 4,500 available time-slots in each minute but this can be easily overwhelmed by the large satellite reception footprints and the increasing numbers of AIS transceivers, resulting in message collisions, which the satellite receiver cannot process. Companies such as exactEarth are developing new technologies such as ABSEA, that will be embedded within terrestrial and satellite-based transceivers, which will assist the reliable detection of Class B messages from space without affecting the performance of terrestrial AIS. The addition of satellite-based Class A and B messages could enable truly global AIS coverage but, because the satellite-based TDMA limitations will never match the reception performance of the terrestrial-based network, satellites will augment rather than replace the terrestrial system. AIS has much longer vertical (than horizontal) transmission – up to the 400 km orbit of the International Space Station (ISS). In November 2009, the STS-129 space shuttle mission attached two antennas—an AIS VHF antenna, and an Amateur Radio antenna—to the Columbus module of the ISS. Both antennas were built in cooperation between ESA and the ARISS team (Amateur Radio on ISS). Starting from May 2010 the European Space Agency is testing an AIS receiver from Kongsberg Seatex (Norway) in a consortium led by the Norwegian Defence Research Establishment in the frame of technology demonstration for space-based ship monitoring. This is a first step towards a satellite-based AIS-monitoring service. In 2009, ORBCOMM launched AIS enabled satellites in conjunction with a US Coast Guard contract to demonstrate the ability to collect AIS messages from space. In 2009, Luxspace, a Luxembourg-based company, launched the RUBIN-9.1 satellite (AIS Pathfinder 2). The satellite is operated in cooperation with SES and REDU Space Services. In late 2011 and early 2012, ORBCOMM and Luxspace launched the Vesselsat AIS microsatellites, one in an equatorial orbit and the other in a polar orbit (VesselSat-2 and VesselSat-1). In 2007, the U.S. tested space-based AIS tracking with the TacSat-2 satellite. However, the received