8-12 July 2013
Africa/Johannesburg timezone
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Improvements in accuracy of a real-time orbital propagator by modelling perturbation forces acting on a LEO CubeSat

Presented by Mr. Thinawanga TSHILANDE on 10 Jul 2013 from 13:50 to 14:10
Type: Oral Presentation
Session: Space Science
Track: Track D2 - Space Science


A precise orbit propagator was developed for implementing on a cubesat's on board computer for real-time orbit position and velocity determination and prediction. Knowledge of the accurate orbital position and velocity of a Low Earth Orbit(LEO) Cubesat orbit is required for various applications such as antenna and imager pointing. Satellite motion is governed by a number of forces other than Earth's gravity alone. The inclusion of pertubation forces such as Earth's aspheric gravity, third body attraction (e.g. Moon and Sun), atmospheric drag and solar radiation pressure, is subsequently required to improve the accuracy of an orbital propagator. Precise orbit propagation is achieved by numerically integrating a set of coupled second order differential equations derived from modelling the satellite's acceleration vector due to all forces acting it. In this study the Runge-Kutta-Fehlberg numerical integration method of the order 7(8) (RKF78), resulting from imbedding RK7 into RK8 was selected for precision integration. This integrator was selected for its stability, high accuracy and computational efficiency. For precision quantification a one-day section of Satellite Laser Ranging -derived precision orbit of the SUNSAT satellite was used as reference. Results, at three-hour intervals, on the improvement in accuracy are demonstrated by the sequential adding of perturbation forces to the initial two-body solution.






Dr Ben Opperman ben.opperman@sansa.org.za




Location: A1-17

Primary authors