Collision avoidance strategies and conjunction risk assessment analysis tool at GISTDA

Thailand Earth Observation satellite (THEOS) known as “Thaichote” is operated by Geo-Informatics and Space Technology Development Agency (GISTDA) since 2008. The orbital mission of THEOS is Sun-Synchronous orbit (SSO) where a number of space objects during the last decades increase rapidly. These are risky to end operational satellite mission early or reduce the mission life time. It becomes a serious issue for on-orbit safety. Therefore, the collision avoidance operation has become a necessary and usual task for all operational satellites. Generally, Conjunction Data Messages (CDMs) notified by Combined Space Operation Center (CSpOC) provides conjunction event information when risks are more over the threshold control in advance 3 days. The earlier analysis is essential to effectively decide avoidance maneuver plantings to mitigate collision risks. In order to handle CDMs and analyze the collision risk in time, GISTDA therefore develops the risk assessment tool to provide the analysis results and support collision avoidance planning. This paper presents the current collision avoidance operation at GISTDA. We provide an overview on the development of the conjunction risk assessment tool known as “ZIRCON” and tool capabilities that can provide the conjunction reports and visualization in the 3D geometry of motions at the Time of Closest Approach (TCA) by displaying target and chaser motion over time along with the uncertainties to support a collision avoidance maneuver. In additions, the recent development of ZIRCON is capable of screening potential object risks by using the Two Line Element (TLE) catalogs provided by the US Strategic Command (USSTRATCOM) against our satellites. Finally, the paper concludes the statistic of conjunction events, collision avoidance experiences for 11-year operation and further development planning to support all Thailand satellites.