Satellite formation and instrument design for autonomous meteor detection

Abstract

A meteoroid entering the Earth atmosphere causes a light phenomenon called meteor. Meteoroids origin from comets or asteroids, these small particles are mostly unchanged since the formation of the solar system. Therefore, observing meteors gives insight on how our solar system evolved and from what materials it consists. Additionally, meteor observations are used to improve meteoroid flux models, which are needed to safely plan space activities. Meteor observations from space offer several advantages compared to ground-based meteor observations, such as greater coverage and an unobstructed view to the meteor as well as weather independence. Using two satellites for meteor observations allows to calculate the trajectory of a meteor and determine its parent body. In this thesis two example satellites are used to develop and design a mission and an instrument for the visual observation of meteors. The first mission is called SOURCE (Stuttgart Operated University Research Cubesat for Evaluation and Education), a three unit CubeSat dedicated to technology demonstrations, demise investigation and meteor observation. Here, a visual monochromatic camera is used to observe meteors and qualify the instrument. The second mission is called FACIS (Formation for Analysis of Cosmic Particles), which consists of a formation of two identical small satellites dedicated to meteor observation and dust measurements. Since two satellites are used, meteors are observed stereoscopically to determine meteor trajectories. Two main challenges of spaceborne meteor observation are addressed in this thesis: The first one is the design of the mission and the instrument. This includes analysing the influence of the satellite bus parameters (e.g. attitude knowledge accuracy) and formation parameters (e.g. satellite distance) on the scientific output of a (stereoscopic) meteor observation mission. Furthermore, the instrument parameters must be analysed and optimized depending on the scientific objective of the mission. Thus, different simulations are developed to evaluate the scientific output depending on satellite bus and formation parameters as well as instrument parameters. These simulations were used to develop the mission, including the design of the instrument and deriving requirements for the satellite bus. Furthermore, the ideal formation parameters depending on the scientific objective and instrument design could be determined.

The second challenge of a space based meteor observation mission is the limited downlink capacity of a satellite. This requires onboard processing of the image data. An algorithm must be used, to identify images containing a meteor and downlink only these images. Existing detection algorithms can not be used, since the satellite moves during an observation and thus, the background is moving as well. Therefore, a new meteor detection algorithm called SpaceMEDAL (Spaceborne MEteor Detection ALgorithm) based on optical flow calculations is developed. This algorithm is tested by developing and using an artificial meteor simulation called ArtMESS (Artificial Meteorvideo Simulation Software) to generate test data and a test bed to display and image this data. A challenge for the algorithm is the limited processing power. Thus, the developed algorithm is accelerated by moving functions to dedicated hardware of the used on board computer. Finally, the observation concept and scientific output of both missions can be determined, by taking into account the instrument parameters, satellite bus and formation parameters as well as the algorithm performance and operational constraints of the satellite. For both missions a concept resulting in a significant observation of meteors could be developed. All in all, this thesis shows that a space based meteor observation mission using small satellites is possible. The main aspects of the mission design were analysed in order to design two different missions. The main aspects addressed in this thesis are the instrument design, the satellite bus and formation requirements and the algorithm development. All three aspects could be successfully revised and the missions and the instrument could be developed. Furthermore, a demonstrator instrument for the SOURCE mission could be built, including the development of the detection algorithm.