Operator and User Perspective of Fractionated AIS Satellite Systems

In 2013 AISSat-2 will join AISSat-1 in providing Norwegian authorities, and their partners, with the extended maritime situational awareness that satellite based AIS systems provides. Since neither satellite has propulsion and both will end up in very similar orbits, there will be times the satellites are covering the same area at the same time, and times where the satellites are separated up to half an orbit. Such a configuration gives rise to some interesting opportunities for the users and challenges for the operators. This paper investigates if an operator can use the variability to the users’ advantage in fulfilling the mission objectives – extending and improving the maritime situational awareness. Intuitively it stands to reason that the user would prefer the satellites to be spaced as far apart as possible, to minimize the mean time between updated information about vessel traffic in an area of interest. However, it is well known that in many areas of interest it is unlikely that a satellite AIS system detects every ship in the area in a single pass. With multiple systems covering the same area at the same time, the probability of vessel detection increases, and this is shown to improve value added products such as fused data products and verification of the AIS reported vessel position