Auteur/autrice : ezahzah

Speaker: Prof. Jun Liu ( University of Science and Technology of China, Hefei, China)

Abtract: Multichannel radar target detection in Gaussian clutter has been a topic of long-standing interest. As customary, it is assumed that a set of homogeneous training data is available in adaptive detection. In practice, it is difficult to collect sufficient homogeneous training data, e.g., due to the presence of several electromagnetic sources. The focus of this talk is on the exploitation of persymmetry for adaptive detection in sample-starved environments where the training data are insufficient.

Abstract: « Low frequency » (~100 MHz) radio astronomy has seen a resurgence in the last decade, with many new and refurbished instruments coming on-line. The principle goals of these instruments are to study astrophysical phenomena such as energetic explosions, merging black holes, and the first stars and galaxies. However these science goals have resulted in agile instruments with large fields of view and large fractional bandwidth, making them well suited to detect and monitor satellites and space debris in low Earth orbit. Of particular note is the Murchison Widefield Array (MWA), which has an all sky field of view, an 80-300 MHz observing band, and an entirely electronic pointing capability. When coupled with commercial FM radio transmitters around Australia that broadcast at 80-100MHz, the MWA can be used as the receiving station of a bistatic passive radar system. In this talk I will describe the hardware and software that we have developed to adapt the MWA to complement Australian Space Domain Awareness efforts.

Speaker: Denis Cutajar (PhD Student), Institute of Space Sciences and Astronomy, University of Malta, Malta.

Abstract: Orbital debris objects pose an ever-increasing threat to active satellites as their orbit cannot be changed to avoid a collision. In recent years, various European institutions have been upgrading their space monitoring capabilities to address this threat. One of the latest such systems is the BIRALES space surveillance system based in Italy. This bi-static radar consists of a 10kW,  radio transmitter in Caligari, Sardinia and a phased array receiver consisting of eight parabolic cylindrical reflectors of the North-South arm of the Istituto Nazionale di Astrofisica (INAF)’s Northern Cross. It represents one of the first Italian radar systems designed for the monitoring of space debris objects.

This work introduces a new software backend, called PyBirales, which was developed for this novel space debris sensor. The system was designed to be a fast, highly configurable software backend for the radio telescope’s acquisition and processing system and whose monitoring and control can be realized by a simple front-end web-based application. The real-time detection of Resident Space Object (RSO) is an essential prerequisite for such a system. It gives the operator an immediate feedback loop on any detections while keeping the storage requirements at a minimum since the raw data can be discarded. The discovery of high-velocity objects is achieved through a specially developed data processing pipeline that can be built using the PyBirales framework. This detection pipeline uses the received antenna voltages to generate several beams, collectively known as a multipixel, covering the Field of View (FoV) of the instrument. The initial results on known objects represent the first steps in extending the growing network of European SST systems.

Speaker: Martin Adams, Dept. Electrical Engineering, Advanced Mining Technology Centre (AMTC), University of Chile, Chile.

Abstract: An increased concern in space situational awareness has resulted from the rise in space debris and its threat to future space missions. For safety reasons, it is critically important to populate and maintain a catalog of orbiting objects. To detect and track space debris, telescopes and radars are typically used, resulting in multiple point measurements, which have to be processed in order to discriminate detections from clutter. Such processes are often based on Bayesian filtering. Conventional filters, such as the Kalman filter, cannot be directly applied to cluttered data problems because a multitarget estimate is required and/or multiple measurements are received. The recently introduced random finite set theory provides an elegant framework within which such problems can be naturally expressed and solved. The application of random sets in multi-target tracking has led to the development of Finite Set Statistics, which provide the basis for filters such as the Probability Hypothesis Density (PHD) filter and more recently the Generalized Labelled Multi-Bernoulli (GLMB) filter, which recently attracted considerable research interest as well as deployment in commercial applications. In the field of Space Situational Awareness, the identification and tracking of orbiting debris travelling at dangerously high speeds is of concern. Determining the number and state (e.g. position and velocity) of debris components which have passed through the field of view of a telescopic sensors, in the presence of measurement noise, clutter and false alarms, is a field of research which can be addressed with FISST based tools. Recent experimental results, demonstrating space debris tracking, based on radar and image data, will be demonstrated.

Authors: Andrew C. Nicholas (Speaker), Christoph R. Englert, Charlie Brown, Ted T. Finne , Kenneth D. Marr, Christopher R. Binz, Liam M. Healy, Scott T. Kindl (U.S. Naval Research Laboratory, Code 7630, 4555 Overlook Ave SW, Washington, DC 20375, USA)

Abstract: The in-situ detection of small orbital debris and micrometeorites, both potentially posing a risk to most space missions, requires a combination of a large sensor area and large time coverage. For example, a sensor with a time area product of 3 m2 per years will make a significant contribution to our understanding of the near Earth small debris population. Deploying large sensors in space, however, is generally resource intensive due to their size and weight. The lightsheet concept allows the creation of a “virtual witness plate,” which is created without any supporting physical structure and therefore presents an attractive opportunity for the deployment of small size, weight, and power instruments anywhere between low Earth orbit to interplanetary space. The lightsheet sensor can be tailored to optimize performance to meet the needs of various applications. In this paper, we describe the lightsheet sensor concept, laboratory/model results and discuss potential orbital debris applications.