Design and prototyping of a low-cost LEO optical surveillance sensor

Optical tracking of LEO objects has been extensively studied and exercised. In this paper, we describe a novel approach surveillance method using an array of collocated fixed Field of View telescopes. In this project a Low-Cost Low-Earth Orbit Surveillance Sensor (LCLeoSen) has been developed to target a similar market as conventional radar systems through the reduction of the cost per sensor while maintaining a similar performance. This cost reduction of the full system will be achieved by employing an array of low-cost optical telescopes as a multi-eye system, with an ultra-wide Field of View capable of imaging the full sky. Having full sky coverage allows each telescope in the system to point in a fixed direction, decreasing the complexity of the subsystems involved.

With the aim of minimising the overall system cost, the system is composed of Commercial Off-The-Shelf hardware components including a wide FoV lens and a high-sensitivity CMOS sensor per telescope in the array, a computing server for processing data, and a mount and dome for the telescope array. The selection of the lenses was decided based on the performance assessment of a prototype. The chosen lens-sensor combination provides an angular resolution which is intended to optimise the detection of objects across the range of LEO altitudes. Another important feature in LEO surveillance is the time tag accuracy. This requirement is met through a system developed, which can ensure a time tag accuracy of ±4 µs.
Considering each telescope’s sensor captures an image every 2-3 seconds, the system has been designed to have near real-time processing capability. The software has been developed to autonomously process all mentioned data and has two main functions: processing the captured images and detecting objects in them. The software module in charge of detecting objects has to efficiently detect objects and distinguish between false detections and actual detections while keeping near real-time performance. Despite the high grade of automation of the system, remote operations requested by the user can be also carried out. Using an array of telescopes with full sky coverage allows correlation of objects detected in different Field of Views in order to improve accuracy and decrease false detections and omissions.

This work was done under a grant awarded by UKSA in the 'Advancing research into space surveillance and tracking' call.