Technology Evolution Analysis of Spacecraft’s Attitude determination and Control System (ADCS)

Kurzfassung

With the beginning of the Space Age at the end of the 1950s, the ―conquest‖ of space began. At the beginning, the units sent to space were quite simple, whereas later they emerged to complex spacecraft that orbit the Earth or explore our solar system nowadays. Thousands of spacecraft have been launched so far. In this day and age, it is hard to imagine our everyday life without the use of astronautics. Its benefits are very common to us, like weather forecasts, the vast programme variety of television or the use of GPS for navigation to name only a few. We use these goods as a matter of course and do not necessarily think about the fact that they are provided by a space borne source. Within the last 60 years, the technology in astronautics steadily advanced. In STELLMANN [1], the general historical evolution of technology is examined and developments in space technology are as well pointed out. Furthermore, this precedent work provides a statistical analysis of mass evolution concentrated on exploration probes’ subsystems. In doing so, it turned out that the mass of the attitude determination and control system (ADCS) in relation to the bus mass of the examined exploration probes showed only a slight reduction over the years. During the last 20 years, this mass proportion even remained approximately constant. On the basis of this result, an examination of the ADCS in detail appears suitable. Thus, the scope of this work is the analysis of the historical evolution of the ADCS components. An examination on the historical evolution of technology might seem to be irrelevant, as people are mostly only interested in the newest available technologies. But George Sarton (1884-1956), the father of the history of science, said in a lecture at Harvard: ―We shall not be able to understand our own science of to-day (I do not say to use it, but to understand it) if we do not succeed in penetrating its genesis and evolution‖ [2]. Sarton relates his statement to science, but it is as well applicable in the context of technology. Hence, it is reasonable to examine the process of development for the attitude determination and control system of spacecraft, especially because astronautics has such a huge, but unconscious standing in mankind’s life. Furthermore, the results of the examination might be useful for engineers as a help for the development of future attitude determination and control techniques, when they can rely on the knowledge and understanding of former components. For the basic understanding of the spacecraft’s attitude determination and control system, this work starts with a system analysis. Therein, spacecraft are classified according their function and the different subsystems of the spacecraft bus are explained. Furthermore, the general functions and the composition of the ADCS are worked out. The different components of the ADCS and their principle of operation as well as different stabilization methods are presented. With the understanding of the functional principle of the ADCS, the investigation on its technology evolution since the beginning of the Space Age can be performed. This investigation is divided in two sections. First, a qualitative research is carried out. For this purpose, the historical development of each ADCS component is pursued. This part of the investigation is focused on the different used techniques and physical principles of the ADCS hardware, whose development is presented in the temporal context. In addition, the general development of space technology is roughly presented. The second part of the investigation is concerned with the quantitative research on the development of the attitude determination and control system. For each component of the ADCS, typical performance parameters are collected and summarized in a database. This database enables that the performance evolution of the ADCS components can be visualized as a function of time. The theory of the used statistical means is described and the results are evaluated according to these. Furthermore, the origin of the dataset, the layout as well as the assumptions are described.