AIS was developed in the 1990s as a high intensity, short-range identification and tracking network and, at the time, it was not anticipated to be detectable from space. Nevertheless, since 2005, various entities have been experimenting with detecting AIS transmissions using satellite-based receivers and, since 2008, companies such as exactEarth, ORBCOMM, Spacequest, Spire and also government programs have deployed AIS receivers on satellites. The time-division multiple access (TDMA) radio access scheme used by the AIS system creates significant technical issues for the reliable reception of AIS messages from all types of transceivers: Class A, Class B, Identifier, AtoN and SART. However, the industry is seeking to address 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.