Improving Satellite Surveillance through Optimal Assignment of Assets

Abstract : To protect Australia's economic concerns and its coastline from attack there is a need for surveillance of a large area of Australia's Sea Air Gap (SAG). Satellites have the advantage of viewing large areas of the earth regularly. But currently there is no indigenous facility to launch satellites dedicated to the surveillance of Australia. With the advent of new MEMS systems, small nano/pico satellites are being built and launched at a fraction of the cost of conventional satellites. This has allowed for the invention and investigation of new concepts for satellite missions. For example, the idea of collaborating clusters of micro-satellites has been used to control arrays of satellites where the functionality is distributed across a group of satellites. Missions such as MIT SPHERES formation flying testbed and the Stanford ORION program are showing the benefits of distributed satellite systems. These benefits include increased survivability, reduced development costs, easier maintenance, and improved revisit times and resolution. Auspace (Tactical Satellites Study: Interim Report RTP-TACSAT-0001-AUS 17-April 2003) is investigating the feasibility of the design of small satellites for short-term missions to be launched into low orbit on demand. This report investigates the use of linear programming to optimize the performance of small satellite constellations where the constellation design for a particular mission is known. The purpose of the proposed constellations is to observe the SAG, and the performance of the constellation is measured in terms of percentage coverage of the SAG. Work done by Auspace Ltd. that demonstrated the use of three constellations to cover the SAC was reproduced using Satellite Tool Kit (STK). The results demonstrate how careful scheduling of assets can lower the size of a constellation designed for surveillance and hence the cost of building and launching such a constellation. (7 tables, 9 figures, 9 refs.)