Tanya Vladimirova

Very-Small-Satellite Design for Distributed Space Missions

A new class of remote sensing and scientific distributed space missions is emerging that requires hundreds to thousands of satellites for simultaneous multipoint sensing. These missions, stymied by the lack of a low-cost mass-producible sensor node, can become reality by merging the concepts of distributed satellite systems and terrestrial wireless sensor networks. A novel, subkilogram, very-small-satellite design can potentially enable these missions. Existing technologies are first investigated, such as standardized picosatellites and microengineered aerospace systems. Two new alternatives are then presented that focus on a low-cost approach by leveraging existing commercial mass-production capabilities: a satellite on a chip (SpaceChip) and a satellite on a printed circuit board. Preliminary results indicate that SpaceChip and a satellite on a printed circuit board offer an order of magnitude of cost savings over existing approaches.

Generation of Musical Sequences with Genetic Techniques

Biologically inspired computational methods have recently attracted much research interest in the field of computer music. This group of methods is a subset of computational intelligence, and is represented by neural networks (NNs), genetic algorithms (GAs), and genetic programming (GP). A common feature of these methods is that they all mimic biological processes: NNs realize the evolutionary device of learning from experience, as humans and other animals do, while GAs and GP are based upon procedures that imitate the laws of natural selection. Genetic algorithms have been shown to display distinct performance improvements compared to enumerative, calculus-based, and random searches of a given arbitrary search space (Goldberg 1989). This is achieved by combining aspects of these search methods to result in a ”guided random” search. The genetic algorithm samples points throughout the search space for their worth, and is ”blind” to any information regarding the search space apart from this measure of worth. This makes genetic search techniques more general and applicable to many search or optimization tasks, as long as an appropriate encoding scheme is employed. By using a population of candidate solutions, rather than single individuals, an inherent parallelism in the search process is apparent. This is because the search for an optimum solution is ”performed over genetic structures (building blocks) that can represent a number of possible so

The Promise of Reconfigurable Computing for Hyperspectral Imaging Onboard Systems: A Review and Trends

Hyperspectral imaging is an important technique in remote sensing which is characterized by high spectral resolutions. With the advent of new hyperspectral remote sensing missions and their increased temporal resolutions, the availability and dimensionality of hyperspectral data is continuously increasing. This demands fast processing solutions that can be used to compress and/or interpret hyperspectral data onboard spacecraft imaging platforms in order to reduce downlink connection requirements and perform a more efficient exploitation of hyperspectral data sets in various applications. Over the last few years, reconfigurable hardware solutions such as field-programmable gate arrays (FPGAs) have been consolidated as the standard choice for onboard remote sensing processing due to their smaller size, weight, and power consumption when compared with other high-performance computing systems, as well as to the availability of more FPGAs with increased tolerance to ionizing radiation in space. Although there have been many literature sources on the use of FPGAs in remote sensing in general and in hyperspectral remote sensing in particular, there is no specific reference discussing the state-of-the-art and future trends of applying this flexible and dynamic technology to such missions. In this work, a necessary first step in this direction is taken by providing an extensive review and discussion of the (current and future) capabilities of reconfigurable hardware and FPGAs in the context of hyperspectral remote sensing missions. The review covers both technological aspects of FPGA hardware and implementation issues, providing two specific case studies in which FPGAs are successfully used to improve the compression and interpretation (through spectral unmixing concepts) of remotely sensed hyperspectral data. Based on the two considered case studies, we also highlight the major challenges to be addressed in the near future in this emerging and fast growing research area.

Characterising Wireless Sensor Motes for Space Applications

This paper is concerned with application of standard wireless COTS protocols to space. Suitability of commercially available wireless sensor mote kits for communication inside and between satellites is investigated. Spacecraft applications of motes are being considered and a set of requirements are identified. Selected mote kits are tested under various scenarios complying with spacecraft testing procedures. The paper details the results of the carried out functional, EMC/I, vibration, thermal and radiation tests.

Mitigation of Radiation Effects in SRAM-Based FPGAs for Space Applications

The use of static random access memory (SRAM)-based field programmable gate arrays (FPGAs) in harsh radiation environments has grown in recent years. These types of programmable devices require special mitigation techniques targeting the configuration memory, the user logic, and the embedded RAM blocks. This article provides a comprehensive survey of the literature published in this rich research field during the past 10 years. Furthermore, it can also serve as a tutorial for space engineers, scientists, and decision makers who need an introduction to this topic.

Development of a Satellite Sensor Network for Future Space Missions

Future spacecraft are envisioned as autonomous, miniature, intelligent and massively distributed systems. At the Surrey Space Centre, a research project is currently under investigation, which aims to develop a picosatellite sensor network using the CubeSat platform. The proposed satellite sensor network will be used to demonstrate technology advances in space, including modified IEEE 802.11 wireless standard for inter-satellite links (ISL), distributed computing for computationally intensive onboard signal processing, and reconfigurable system-on-a-chip (SoC) design.

ESPACENET: A Framework of Evolvable and Reconfigurable Sensor Networks for Aerospace–Based Monitoring and Diagnostics

There is an increasing need to develop flexible, reconfigurable, and intelligent multi-spacecraft sensing networks for aerospace-based monitoring and diagnostics. Technical advancements in ad hoc networking, MEMS devices, low-power electronics, adaptive and reconfigurable hardware, micro-spacecraft, and micro-sensors have enabled the design and development of such highly integrated space wireless sensor networks. This paper proposes the framework for an evolvable sensor network architecture, investigated as part of the ESPACENET project, collocated at the University of Edinburgh, Essex, Kent and Surrey. The aim is to design a flexible and intelligent embedded network of reconfigurable piconodes optimised by a hierarchical multi-objective algorithm. Although the project is targeted at aerospace applications, the same intelligent network can be used for many earth bound applications such as environmental and medical diagnostics

Enabling Technologies for Distributed Picosatellite Missions in LEO

Picosatellites are very small satellites with a mass of less than 1 kg. A number of picosatellite projects have been undertaken by University and government research teams. Constellations of picosatellites could prove to be a low-cost and efficient solution to remote sensing in LEO. Reconfiguration and adaptation are capabilities, which are of critical importance to such constellations. A conceptual model of a constellation consisting of heterogeneous picosatellite nodes with a payload function distributed among the nodes will be outlined. Enabling technologies for picosatellite constellations such as wireless intersatellite links, reconfigurable onboard computing and distributed processing will be discussed. A proposal for a test-bed to demonstrate a reconfigurable distributed computing platform will be outlined

Embedded intelligent imaging on-board small satellites

Current commercial Earth Observation satellites have very restricted image processing capabilities on-board. They mostly operate according to a ‘store-and forward’ mechanism, where the images are stored on-board after being acquired from the sensors and are downlinked when contact with a ground station occurs. However, in order for disaster monitoring satellite missions to be effective, there is a need for automated and intelligent image processing onboard. In fact, the need for increasing the automation on-board is predicted as one of the main trends for future satellite missions. The main factors that hold back this concept are the limited power and computing resources on-board the spacecraft. This paper reviews existing image processing payloads of earth observing small satellites. An autonomous change detection system is proposed to demonstrate the feasibility of implementing an intelligent system on-board a small satellite. Performance results for the proposed intelligent imaging system are estimated, scaled and compared to existing hardware that are being used in the SSTL DMC satellite platform.

Fault-Tolerant Encryption for Space Applications

This paper is concerned with the use of commercial security algorithms like the Advanced Encryption Standard (AES) in Earth observation small satellites. The demand to protect the sensitive and valuable data transmitted from satellites to ground has increased and hence the need to use encryption on board. AES, which is a very popular choice in terrestrial communications, is slowly emerging as the preferred option in the aerospace industry including satellites. This paper first addresses the encryption of satellite imaging data using five AES modes - ECB, CBC, CFB, OFB and CTR. A detailed analysis of the effect of single even upsets (SEUs) on imaging data during on-board encryption using different modes of AES is carried out. The impact of faults in the data occurring during transmission to ground due to noisy channels is also discussed and compared for all the five modes of AES. In order to avoid data corruption due to SEUs, a novel fault-tolerant model of AES is presented, which is based on the Hamming error correction code. A field programmable gate array (FPGA) implementation of the proposed model is carried out and measurements of the power and throughput overhead are presented.