The increasing number of space objects that are orbiting around the Earth, from large satellites to small CubeSats, creates the need for a system that detects and tracks space debris in order to have it localized and not to collide with the satellites. Certainly, there are on ground systems using both radar and optical techniques to detect and track space debris, however, these systems are expensive and are not accessible to every potential final user, academic or commercial. Thus, a reliable, easily accessible and cheap, compared to the established systems, implementation would be useful. This paper analyses and explores the possibility to use a CubeSat mounted passive forward scattering radar (FSR) equipped with a 3D phase array antenna (3D-PAA) for space situational awareness purposes. In the future, the collected data could be used to create a database of space debris that could be used to prevent space disasters and damages.
In a passive bistatic radar (PBR) configuration, the receiver collects signals from third party sources, also known as illuminators of opportunity, to retrieve information from objects that could have reflected the signals coming from those illuminators of opportunity. The satellites could act as illuminators, and the growing number of them, namely commercial satellite constellations, would help to provide good coverage. Besides, the system is mounted on a CubeSat, so there is no need for atmosphere or orbit compensation proceedings. Therefore, the choice of the PBR seems appropriate. Furthermore, since there is no active transmitter, the solution should be cheaper and more viable.
Considering that the receiver is an integral part of the PBR, highly competent software, processing, and hardware capacities are needed. In particular, in this work we are introducing the use of a novel antenna, the so called 3D-PAA. The benefits of using the 3D-PAA include the ability of generating multiple beams, electrical scanning and no moving parts. Because the device could work with multiple beams, it could detect electromagnetic signals from multiple illuminators of opportunity at the same time. If we could detect the same space debris from various sources, we could increase the reliability of the collected data. Moreover, with multiple beams we could track multiple space debris simultaneously. Similarly, as there are no moving parts, there is no maintenance, which decreases the cost of the system. Finally, thanks to the electrical scanning the search and lock on illuminators can be performed more effectively, enhancing the overall system operation time.
In addition, the paper examines the design of the joint system and hardware scheme of the 3D-PAA, as well as the possible processing and algorithm approaches the compiled signals and data could go through. Additionally, it includes power budget analysis, the pertinent SNR requirement computations, maximum distance availability and minimum detectable target size.