OPTIMISASI MANUVER KOREKSI UNTUK MENJAGA WAKTU LOKAL SATELIT LAPAN-A4

• Main Author: Rizki Zuhri, Muhammad
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/62037
• Institution: Institut Teknologi Bandung

To achieve a sun-synchronous orbit (SSO), a satellite orbit needs to have a nodal precession rate value equals to the revolution rate of the Earth to the Sun, which is 360°/year. The nodal precession rate, by using J2 zonal harmonic perturbation, is affected by some orbital element values: semi major axis, eccentricity, and inclination. This particular value of nodal precession rate helps the satellite to maintain its local time throughout its lifespan. However, sun-synchronous satellites generally encounter significant perturbations from the atmospheric drag and the Earth’s oblateness during its operation and could potentially change the value of three orbital elements that is affecting the nodal precession rate . Consequently, the local time of the satellite could potentially drift gradually, so correction maneuvers are required. In this research, the author analyzed potential maneuvers to maintain the local time of an SSO satellite, which are inclination correction, altitude or semi major axis correction, and RAAN (Right Ascencion of Ascending Node) correction, for 5 years of operation of LAPAN-A4 satellite. The analysis was conducted by simulation using GMAT (General Mission & Analysis Tools) software with LAPAN-A4 satellite as a case study. Furthermore, this research also attempted to find the optimum maneuvering period, time interval between maneuvers, and the thrust direction and profile for each potential maneuver at once. Maneuvering period optimization was performed by using surrogate-assisted optimization technique via R software, whereas thrust direction and profile optimization was performed in GMAT. The optimizations aimed to give a best maneuvering plan for LAPAN to be implemented on LAPAN-A4 satellite. The results showed that RAAN correction maneuver is not effective since the estimated fuel consumption is much more compared to inclination or semi major axis correction maneuver. It was also concluded that the semi major axis correction maneuver is better compared to the inclination correction maneuver because it gives less fuel consumption and less maximum local time drift. The last but not least, the most optimum maneuvering plan obtained from this research was a semi major axis correction maneuver with 4 months of maneuvering period with a certain correction targeting strategy.