Satellite AIS (S-AIS)

Satellite AIS is the reception of ship AIS broadcasts by satellites rather than coastal receivers, extending coverage to the open ocean far beyond the roughly 40-nautical-mile terrestrial range. It is the backbone of wide-area maritime domain awareness, letting analysts track vessels across whole oceans, detect AIS gaps that mark dark activity, and cross-check positions against imagery. Message collisions in dense traffic and deliberate spoofing are its main data-quality limits.