Diwata-1 Target Pointing Error Assessment using orbit and space environment prediction model

Abstract

Diwata-1 is the Philippines’ first Earth observation microsatellite launched to space through the International Space Station. It has an altitude of 400 km and a velocity of 7 km/s. As an observation satellite, it is required to have high target pointing accuracy. However, being a low Earth orbit microsatellite, it experiences stronger external disturbances compared to larger and higher altitude satellites. Such disturbances are from the sun, and the Earth’s albedo and magnetic field. How these disturbances impact the pointing accuracy of the satellite must be determined to improve the setting of satellite missions, where such disturbances would be minimal. In addition, the satellite’s orbit decays quickly due to these disturbances, which means accurate satellite prediction is also critical in setting correct parameters for its targeting operations. In this paper, a comparison of different satellite prediction models to the Diwata-1 telemetry in varying TLE ages were done to determine which model fits best to the satellite’s orbit and what corrections are needed to minimize the difference between the actual satellite position from the predicted version, and in effect improve the satellite’s pointing accuracy. In addition, cases comparing the target area set during the creation, and the upload of the satellite command with the actual location captured by the satellite, were linked to disturbances from the sun and the earth to determine if these disturbances affect the target pointing of the satellite.