Scalability and Modularity of a Solar Panel Based Space Debris Detector

Abstract

Introduction Space debris is a threat for manned and unmanned space missions. Man-made junk circulating the Earth pose a risk to impact and damage or even destroy a spacecraft, which in turn would lead to even more debris in orbit. While larger elements, such as upper stages and old satellites out of service but also smaller pieces in the upper centimeter range are tracked from ground in order to avoid collisions, there are 128 millions of particles with diameters in the millimeter range which cannot be detected and followed today [1]. Moreover, after the discontinuance of the Shuttle program, no hardware can be retrieved from space in order to investigate the evolution of damages caused by these fine impactors. Environmental simulation models for micro-meteoroids and space debris currently available, such as the ESA (European Space agency) MASTER (Meteoroid and Space Debris Terrestrial Environment Reference) or the NASA (National Aeronautics and Space Administration) ORDEM (Orbital Debris Engineering Model) tools provide estimates for the particle fluxes for all sizes, but with great uncertainty for very small particles due to the lack of data (Chapter 11). In order to gain a better understanding on the small debris particle situation in Earth orbit, the DLR (Deutsches Zentrum für Luft- und Raumfahrt e.V.) Institute of Space Systems developed an in-situ detector which uses the solar panel areas for detection. The so-called “SOLID” (solar panel based space debris impact detector) is basically a thin layer with a grid of copper lines which are frequently powered with low-current in order to identify open circuits which indicate a damage of the respective area. The advantages of this detector concept are the low mass and energy demand as well as the high degree of flexibility for customization and adaptation to a wide range of space systems (Chapter 4). So far, the first flight model is performing its on-orbit verification on the TechnoSat satellite of the University of Berlin, launched in summer 2017. Another version is currently under development to be implemented in the small and compact satellite series of DLR. Both versions are significantly different in size, detector layout, and computation electronics set-up and development approach, indicating the flexibility of the concept itself. In 1978, the NASA scientist Donald J. Kessler proposed that a chain reaction of exploding space debris can end up making space activities and the use of satellites impossible for generations. The number of objects that the space nations keep launching into the lower earth orbit (LEO) can create such a dense environment above the planet that inevitable collisions could cause a cascading effect. The space junk generated by collisions could make further collisions much more possible. Table 1 shows that there is a great amount of small particles with over trillions particles larger than 100μm. This particle size is generally considered the threshold for when particles may cause considerable satellite damage. Due to the challenge of detecting these small particles, the exact distribution is, however, very uncertain. Discrete events such as satellite breakups or collisions each cause hundreds or thousands of new space debris objects. Regularly detecting micrometeoroids and orbital debris (Chapter 3) with in-situ detectors will improve the data quality for the small particle distributions and provide close to real-time coverage on particle populations created by discrete events.