Dr Chris Bridges


Lecturer in On-Board Data Handling (OBDH)
PhD, BEng, MIEEE

Biography

Biography

Dr Chris Bridges obtained a BEng in Electronics at the University of Greenwich and was previously employed at BAE Systems in Rochester, Kent. He joined Surrey Space Centre as a PhD student in April 2006 under Dr Tanya Vladimirova and has since been successful in obtaining Post Doctorial positions in the VLSI Design & Embedded Systems and Astrodynamics Groups. He is now the On-Board Data Handling Group lead and is published in agent computing, Java processing, and multi-core system-on-a-chip technologies. He runs the Implementing Intelligence for Aerospace Session at the IEEE/AIAA Aerospace Conference at Big Sky, Montana, USA.

Chris is the Surrey Space Centre (SSC) Lead Engineer & Researcher for the collaboration with Surrey Satellite Technology Ltd (SSTL) mission 'Surrey Training Research and Nanosatellite Demonstrator' programme (STRaND). STRaND-1 began in April 2010 and aims to fly the latest smartphone technologies and advanced attitude orbit and control system (AOCS). STRaND-2 aims to fly two nanosatellites towards close-proximity operations/imaging and rendezvous & docking demonstration utilising the Microsoft Kinect.

Chris is passionate about communicating all things space through his teaching, regular media, and social websites. Read more about Chris on his UK Space Agency Career Profile page. Keep up to date on current events & news on the Surrey Space Centre Facebook or SpaceAtSurrey Twitter!

Follow @DrChrisBridges

Research interests

Research interests include agents, middleware/network stacks, IP cores, multi/network processors, embedded systems, distributed satellite systems, distributed/cloud computing, CubeSat development, and neuro-morphology.

Research collaborations

Visual Inspection Payload - Astrodynamics Group

The feasibility of performing a visual inspection mission between two satellites is being investigated utilising a microelectromechanical (MEMS) thruster built by EADS Astrium. The combined thrusting, imaging, and processing requirements will go towards a new integrated hardware and software payload design.

AMSAT-UK and ESA - ESEO Mission

The OBDH Group has been bring together technologies for a VHF and L-band communication system where Dr Bridges' group and students have been working on automotive components and software defined radio technologies to fly a new radio architecture.

Teaching

Spacecraft Avionics - since Spring 2014, Module Link

Computers & Programming II: Microprocessor Organisation & Design - since Spring 2013, Module Link

Digital Design with VHDL Labs - Autumn 2007 & Autumn 2008, Lectures since Spring 2013 Module Link

Multi-Disciplinary Design Project - since Spring 2014, Module Link

Spacecraft Bus Subsystems - Power, TT&C, & On-board Data Handling (OBDH) - Spring 2012 to 2014 (retired)

Dynamics and Control of Spacecraft Labs - Autumn 2010 to 2013 (retired)

Departmental duties

Member of Electronic Engineering Industrial Advisory Board (IAB)

Surrey Space Centre Marketing & Website Management

Surrey Space Centre Social Media (Facebook & Twitter)

Affiliations

IEEE/AIAA Aerospace Conference, Big Sky, Montana, USA - Session Chair in Software and Computing, www.aeroconf.org

Chair of the U.K. CubeSat and Nanosatellite Forum, Bringing together industry, academia, entrepreneurs for one voice to government, www.cubesatforum.org.uk

AMSAT-UK Member and OFCOM Radio License Holder (2E0OBC)

Press Releases & Interviews

Raspberry Pi Foundation, Compute Module CubeSats (Guest Blog), 16 Oct 2015

The Guardian, The space industry is growing - and looking for talented postgrads, 14 Jan 2015

Engineering and Physical Sciences Research Council, Pioneer 10 - Space Man (p.14-15), Summer 2013

Uni. of Surrey, Surrey Space Centre Lecturer Nominated for Sir Arthur C. Clarke Award, 28 June 2013

Daily Mail, UK to launch first-ever satellite controlled by a mobile phone… and the scientists have chosen a Google Nexus handset, 8 Feb 2013

BBC Radio 4, Material World: TB vaccine, Satellites, Lake Ellsworth, Antarctic Station, 7 Feb 2013

Gizmodo, UK Scientists Are Launching a Satellite Powered By… a Google Nexus One?, 7 Feb 2013

Stuff, Space exploration? There's an app for that, 7 Feb 2013

BBC News: Science & Environment, Strand-1 'phone-sat' ready for orbit, 7 Feb 2013

The Good Times Guide, Surrey in Space: TG2Surrey Attempts to Boldly Go Where Many More Informed Men Have Gone Before…, Jan 2013

TechRepublic, Why Microsoft's Kinect and Google's Android are headed to space, 29 June 2012

United Kingdom Space Agency (UKSA), Dr Chris Bridges - Career Profile, June 2012

BBC News: Science & Environment, Thinking outside the box in space, 29 May 2012

New Scientist, Space apps: smart-phone at heart of satellite mission, 5 October 2011

The Observer, How Britain can rejoin the space race, 3 July 2011

Fox News, Ground Control to Major Smartphone? NASA Wants Phones to Pilot Spaceships, 11 February 2011

BBC News: Science & Environment, Mobile phone to blast into orbit, 24 January 2011

University of Surrey, Minister of State for Universities and Science praises work of Surrey scientists, 21 July 2010

My publications

Publications

Bridges CP, Yeomans B, Iacopino C, Frame T, Schofield A, Kenyon S, Sweeting MN (2013) Smartphone Qualification & Linux-based Tools for CubeSat Computing Payloads
Modern computers are now far in advance of satellite systems and leveraging of these technologies for space applications could lead to cheaper and more capable spacecraft. Together with NASA AMES?s PhoneSat, the STRaND-1 nanosatellite team has been developing and designing new ways to include smart-phone technologies to the popular CubeSat platform whilst mitigating numerous risks. Surrey Space Centre (SSC) and Surrey Satellite Technology Ltd. (SSTL) have led in qualifying state-of-the-art COTS technologies and capabilities - contributing to numerous low cost satellite missions. The focus of this paper is to answer if 1) modern smart-phone software is compatible for fast and low cost development as required by CubeSats, and 2) if the components utilised are robust to the space environment. The STRaND-1 smart-phone payload software explored in this paper is united using various open-source Linux tools and generic interfaces found in terrestrial systems. A major result from our developments is that many existing software and hardware processes are more than sufficient to provide autonomous and operational payload object-to-object and filebased management solutions. The paper will provide methodologies on the software chains and tools used for the STRaND-1 smartphone computing platform, the hardware built with space qualification results (thermal, thermal vacuum, and TID radiation), and how they can be implemented in future missions.
Vladimirova T, Wu X, Bridges CP (2008) Development of a satellite sensor network for future space missions 2008 IEEE AEROSPACE CONFERENCE, VOLS 1-9 pp. 153-162
Bridges CP, Palmer P (2011) Demonstrating Visual Inspection of Solar Sail Surfaces http://www.congrex.nl/11a01/
Underwood CI, Pellegrino S, Lappas V, Bridges CP, Taylor BO, Chhaniyara S, Theodorou T, Shaw P, Arya M, Breckinridge J, Hogstrom K, Patterson K, Steeves J, Wilson L, Horri N (2013) Autonomous Assembly of a Reconfigurable Space Telescope (AAReST) ? A CubeSat/Microsatellite Based Technology Demonstrator Proceedings of the 27th Annual AIAA/USU Conference on Small Satellites (SmallSat 2013)
Future space telescopes with diameter over 20 m will require in-space assembly. High-precision formation flying has very high cost and may not be able to maintain stable alignment over long periods of time. We believe autonomous assembly is a key enabler for a lower cost approach to large space telescopes. To gain experience, and to provide risk reduction, we propose a demonstration mission to demonstrate all key aspects of autonomous assembly and reconfiguration of a space telescope based on multiple mirror elements. The mission will involve two 3U CubeSat-like nanosatellites (?MirrorSats?) each carrying an electrically actuated adaptive mirror, and each capable of autonomous un-docking and re-docking with a small central ?9U? class nanosatellite core, which houses two fixed mirrors and a boom-deployed focal plane assembly. All three spacecraft will be launched as a single ~40kg microsatellite package.
Underwood C, Pellegrino S, Lappas VJ, Bridges C, Baker J (2014) Using cubesat/micro-satellite technology to demonstrate the autonomous assembly of a reconfigurable space telescope (AAREST) Proceedings of the International Astronautical Congress, IAC 5 pp. 3430-3439
Future space telescopes with diameter over 20 m will require new approaches: either high-precision formation flying or in-orbit assembly. We believe the latter holds promise as a potentially lower cost and more practical solution in the near term, provided much of the assembly can be carried out autonomously. To gain experience, and to provide risk reduction, we propose a combined mico/nano-satellite demonstration mission that will focus on the required optical technology (adaptive mirrors, phase-sensitive detectors) and autonomous rendezvous and docking technology (inter-satellite links, relative position sensing, automated docking mechanisms). The mission will involve two "3U" Cubesat-like nanosatellites ("MirrorSats") each carrying an electrically actuated adaptive mirror, and each capable of autonomous un-docking and re-docking with a small central "15U" class micro/nano-satellite core, which houses two fixed mirrors and a boom-deployed focal plane assembly. All three spacecraft will be launched as a single
Bridges CP, Vladimirova T (2008) Real-Time Agent Computing Platform for Distributed Satellite Systems International Review on Computers and Software 3 (6) pp. 651-665
Erlank AO, Bridges CP (2015) A Multicellular Architecture towards Low-Cost Satellite Reliability 2015 NASA/ESA CONFERENCE ON ADAPTIVE HARDWARE AND SYSTEMS (AHS)
Bridges CP, Vladimirova T (2011) Real-time agent middleware experiments on java-based processors towards distributed satellite systems IEEE Aerospace Conference Proceedings pp. 1-10
Distributed satellite systems are large research topics, spanning many fields such as communications, networking schemes, high performance computing, and distributed operations. DARPA's F6 fractionated spacecraft mission is a prime example, culminating in the launch of technology demonstration satellites for autonomous and rapidly configurable satellite architectures. Recent developments at Surrey Space Centre have included the development of a Java enabled system-on-a-chip solution towards running homogenous agents and middleware software configurations.
Bridges CP, Sauter L, Palmer P (2011) Formation deployment & separation simulation of multi-satellite scenarios using SatLauncher IEEE Aerospace Conference Proceedings pp. 1-9
Satellite constellation deployment for formation flying missions is one of the key areas for consideration when realizing the final constellation with reduced propellant mass requirements on the propulsion system. The use of a single launch vehicle to deploy multiple satellites into a formation is faster and cheaper but there is greater risk of collision. This risk must be managed with the competing desire to establish a relatively tight formation for better inter-satellite communication. The launcher attitude, satellite injection times and velocities are key parameters to safely achieve a given separation distance and distribution. This paper presents a visual simulator to propagate the satellite trajectories from the launcher using an expanded definition of Hill's equations, and extending to polar relative motion. It is assumed that a simple launcher is used which is incapable of reposition once in orbit. Low injection velocities are exploited to inject large numbers satellites into a stable constellation. Utilizing small tight natural motion formations help to reduce perturbations and the propellant mass required for formation maintenance. SatLauncher is a new visualization tool for investigating the relative motion and key parameters between satellites in these new missions and applications for multi-satellite launchers without the need for any further industrial tool. The QB50 mission is taken forward as a representative scenario requiring our latest software tool and new methods are presented towards collision free formation deployment.
Underwood C, Pellegrino S, Lappas VJ, Bridges CP, Baker J (2015) Using CubeSat/micro-satellite technology to demonstrate the Autonomous Assembly of a Reconfigurable Space Telescope (AAReST) Acta Astronautica 114 pp. 112-122
Future space telescopes with diameter over 20 m will require new approaches: either high-precision formation flying or in-orbit assembly. We believe the latter holds promise at a potentially lower cost and more practical solution in the near term, provided much of the assembly can be carried out autonomously. To gain experience, and to provide risk reduction, we propose a combined micro/nano-satellite demonstration mission that will focus on the required optical technology (adaptive mirrors, phase-sensitive detectors) and autonomous rendezvous and docking technology (inter-satellite links, relative position sensing, automated docking mechanisms). The mission will involve two "3U" CubeSat-like nanosatellites ("MirrorSats") each carrying an electrically actuated adaptive mirror, and each capable of autonomous un-docking and re-docking with a small central "15U" class micro/nano-satellite core, which houses two fixed mirrors and a boom-deployed focal plane assembly. All three spacecrafts will be launched as a single ~40 kg micro-satellite package. The spacecraft busses are based on heritage from Surrey's SNAP-1 and STRaND-1 missions (launched in 2000 and 2013 respectively), whilst the optics, imaging sensors and shape adjusting adaptive mirrors (with their associated adjustment mechanisms) are provided by CalTech/JPL. The spacecraft busses provide precise orbit and attitude control, with inter-satellite links and optical navigation to mediate the docking process. The docking system itself is based on the electromagnetic docking system being developed at the Surrey Space Centre (SSC), together with rendezvous sensing technology developed for STRaND-2. On orbit, the mission profile will firstly establish the imaging capability of the compound spacecraft before undocking, and then autonomously re-docking a single MirrorSat. This will test the docking system, autonomous navigation and system identification technology. If successful, the next stage will see the two MirrorSat spacecraft undock and re-dock to the core spacecraft in a linear formation to represent a large (but sparse) aperture for high resolution imaging. The imaging of stars is the primary objective, but other celestial and terrestrial targets are being considered. Teams at CalTech and SSC are currently working on the mission planning and development of space hardware. The autonomous rendezvous and docking system is currently under test on a 2D air-bearing table at SSC, and the propulsion and precis
Bridges CP, Taylor B, Horri N, Underwood CI, Kenyon S, Barrera-Ars J, Pryce L, Bird R (2013) STRaND-2: Visual Inspection, Proximity Operations &
Nanosatellite Docking

The Surrey Training Research and Nanosatellite
Demonstrator (STRaND) programme has been success in identifying and creating a leading low-cost nanosatellite programme with advanced attitude and orbit control system (AOCS) and experimental computing platforms based on smart-phone technologies. The next demonstration capabilities, that provide a challenging mission to the existing STRaND platform, is to perform visual inspection, proximity operations and nanosatellite docking. Visual inspection is to be performed using a COTS LIDAR system to estimate range and pose under 100 m. Proximity operations are controlled using a comprehensive guidance, navigation and control (GNC) loop in a polar form of the Hills Clohessy Wiltshire (HCW) frame
including J2 perturbations. And finally, nanosatellite docking is performed at under 30 cm using a series of tuned magnetic coils. This paper will document the initial experiments and
calculations used to qualify LIDAR components, size the mission thrust and tank requirements, and air cushion table demonstrations of the docking mechanism.
Maheshwarappa MR, Bowyer M, Bridges CP (2015) Software Defined Radio (SDR) architecture to support multi-satellite communications IEEE Aerospace Conference Proceedings 2015-June
© 2015 IEEE.Software Defined Radio (SDR) is a key area to realise new software implementations for adaptive and reconfigurable communication systems without changing any hardware device or feature. A review on efficient use of limited bandwidth and increasing distributed satellite missions can lead to the need for a generic yet configurable communication platform that can handle multiple signals from multiple satellites with various modulation techniques, data rates and frequency bands that must be compatible to typical small satellite requirements. SDR is beneficial for space applications as it can provide the flexibility and re-configurability and this is driven by fast development times, new found heritage, reduced cost, and low mass Commercial Off-The-Shelf (COTS) components. The implementation of a combined System-On-Chip (SoC) and SDR communication platform enables additional reduction in cost as well as mass. This paper proposes a SDR architecture in which Field Programmable Gate Array (FPGA) System-on-Chip (SoC) is paired with a Radio Frequency (RF) programmable transceiver SoC to solve back-end and front-end re-configurability challenges respectively. The test-bed is aimed at implementing the signal processing software functions in both the dual-core ARM processors and associated FPGA fabric. The distribution of the functions between the FPGA fabric and dual-processor is based on profiling experiments using signal processing blocks, implemented on the development platform, in order to identify where bottlenecks exist. This paper discusses further the results from the new multi-signal / multi-satellite pipeline architecture and the subsequent bandwidth, data rate and processing requirements. Aspects of implementing and testing signal processing chains needed for CubeSat Telecommand, Telemetry and Control (TT&C) are presented together with initial results. Thus the proposed technology not only contributes for a lightweight and portable ground station but also for an on-board satellite transceiver.
Vladimirova T, Bridges CP, Paul JR, Malik SA, Sweeting MN (2010) Space-based wireless sensor networks: Design issues IEEE Aerospace Conference Proceedings
Vladimirova T, Wu X, Jallad A-H, Bridges CP (2007) Distributed computing in reconfigurable picosatellite networks NASA/ESA Conference on Adaptive Hardware and Systems, Proceedings pp. 682-689
Maheshwarappa MR, Bridges CP (2014) Software defined radios for small satellites Proceedings of the 2014 NASA/ESA Conference on Adaptive Hardware and Systems, AHS 2014 pp. 172-179
Clusters, constellations, formations, or 'swarms' of small satellites are fast becoming a way to perform scientific and technological missions more affordably. As objectives of these missions become more ambitious, there are still problems in increasing the number of communication windows, supporting multiple signals, and increasing data rates over reliable intersatellite and ground links to Earth. Also, there is a shortage of available frequencies in the 2 m and 70 cm bands due to rapid increase in the number of CubeSats orbiting the Earth - leading to further regulatory issues. Existing communication systems and radio signal processing Intellectual Property (IP) cores cannot fully address these challenges. One of the possible strategies to solve these issues is by equipping satellites with a Software Defined Radio (SDR). SDR is a key area to realise various software implementations which enable an adaptive and reconfigurable communication system without changing any hardware device or feature. This paper proposes a new SDR architecture which utilises a combination of Field Programmable Gate Array (FPGA) and field programmable Radio Frequency (RF) transceiver to solve back-end and front- end challenges and thereby enabling reception of multiple signals or satellites using single user equipment. © 2014 IEEE.
Bridges CP, Kenyon S, Underwood CI, Sweeting MN (2011) STRaND: Surrey Training Research and Nanosatellite Demonstrator Proceedings of the1st IAA Conference on University Satellite Missions and CubeSat Workshop
Duke R, Bridges C, Stewart B, Taylor B, Massimiani C, Forshaw JL, Aglietti G (2016) Integrated Flight & Ground Software Framework for Fast Mission Timelines Proceedings of 67th International Astronautical Congress 2016
Flight and ground segment software in university missions is often developed only after hardware has matured sufficiently towards flight configuration and also as bespoke codebases to address key subsystems in power, communications, attitude, and payload control with little commonality. This bespoke software process is often hardware specific, highly sequential, and costly in staff/monitory resources and, ultimately, development time. Within Surrey Space Centre (SSC), there are a number of satellite missions under development with similar delivery timelines that have overlapping requirements for the common tasks and additional payload handling. To address the needs of multiple missions with limited staff resources in a given delivery schedule, computing commonality for both flight and ground segment software is exploited by implementing a common set of flight tasks (or modules) which can be automatically generated into ground segment databases to deliver advanced debugging support during system end-to-end test (SEET) and operations.
This paper focuses on the development, implementation, and testing of SSC?s common software framework on the Stellenbosch ADCS stack and OBC emulators for numerous missions including Alsat-1N, RemoveDebris, SME-SAT, and InflateSail. The framework uses a combination of open-source embedded and enterprise tools such as the FreeRTOS operating system coupled with rapid development templates used to auto-generate C and Python scripts offline from ?message databases?. In the flight software, a ?core? packet router thread forwards messages between threads for inter process communication (IPC). On the ground, this is complemented with an auto-generated PostgreSQL database and web interface to test, log, and display results in the SSC satellite operations centre. Profiling is performed using FreeRTOS primitives to manage module behaviour, context, time and memory ? especially important during integration. This new framework has allowed for flight and ground software to be developed in parallel across SSC?s current and future missions more efficiently, with fewer propagated errors, and increased consistency between the flight software, ground station and project documentation.
Bridges CP, Burgon R, Shirville G, Waldram M, Cullen D, Guillo C, Greenland S, Dalgleish B (2014) An output of the 2014 UK CubeSat Workshop: White Paper on U.K. CubeSat Regulation & UKSA CubeSat Consultation
The U.K. CubeSat Forum held a one-day workshop meeting at the Harwell Science and Innovation Campus, Harwell, U.K. in May 2014. One objective of the workshop was for the U.K. CubeSat community ? represented by the workshop delegates ? to discuss the current and future context for gaining approval, i.e. U.K. government issued licence, to launch and operate a U.K.-registered CubeSat or nanosatellite. This discussion arose given the pre-workshop widespread U.K. community view that to do this within a U.K. context involved significantly more effort, resources and costs than in other countries and perceived to be disproportionate to the overall CubeSat philosophy of low-cost, low-resource and rapid implementation of missions. The workshop attendees (~120 delegates) were split into three parallel discussion groups to discuss this point.
Bridges CP, Vladimirova T (2012) Agent Computing Platform for Distributed Computing in Space IEEE Transactions on Aerospace and Electronic Systems
Today?s mobile devices and countless other embedded devices now aim to use networking technologies utilizing the latest electronics and software to provide new functions. Distributed satellite systems, seen to be analogous to mobile ad-hoc networks, perform new mission functions with high mobility and intermittent connectivity which make satellite network management and operations difficult. New drivers and requirements are outlined for node and network levels in any given topology requiring real-time client-server or peer-to-peer networking applications. To meet these requirements, a novel agent computing platform is proposed utilizing technologies from the multi-processor and agent middleware fields for real-time Java networking and mobile ad-hoc network based distributed computing applications at a minimal overhead to existing systems. The Java Optimised Processor (JOP) is investigated and embedded into an existing LEON3 based system-on-a-chip design to provide a new fault-tolerant, parallel processing, and network functionalities. Agent middleware is discussed and compared for porting to the new dual processor design with a new middleware instance manager thread to enable software resets at runtime on the Java processor without halting the processor. After verification, these two technologies are combined and discussed in depth to highlight key technological problems of this real-time agent computing platform implementation.
Vladimirova T, Bridges CP, Prassinos G, Wu X, Sidibeh K, Barnhart DJ, Jallad A-H, Paul JR, Lappas V, Baker A, Maynard K, Magness R (2007) Characterising wireless sensor motes for space applications NASA/ESA Conference on Adaptive Hardware and Systems, Proceedings pp. 43-50
Kenyon S, Barrera-Ars J, Pryce L, Liddle D, Bridges CP, Underwood C (2012) STRAND-2: Kinecting two cubesats in flight Proceedings of the International Astronautical Congress, IAC 6 pp. 4554-4571
Surrey Satellite Technology Ltd and the University of Surrey have a long history of demonstrating new terrestrial COTS technologies in space, with the aim of reducing the cost of space applications. The STRaND-1 mission is the most recent example of this cooperative history, demonstrating the use of mobile phone technology as the central avionics for a nanosatellite. The STRaND-1 mission is planned for launch in 2012. The second mission in the STRaND programme is now under development, under the same funding arrangement as STRaND-1 (equally and internally funded by SSTL and SSC), and the aim is to be just as ambitious as the first STRaND mission. One key technology to demonstrate is the use of a Microsoft Kinect (TM) sensor suite in orbit, as a low cost alternative to lidar and machine imaging, to enable a docking mission between two CubeSats. If successful, the STRaND-2 mission would be the first demonstration of autonomous docking of nano-scale spacecraft. This paper discusses how the STRaND philosophy can be applied to a second mission. It then outlines the mission concept, highlighting key technology areas including the docking suite and propulsion system, before detailing some of the orbit dynamics of docking two CubeSats together. Initial mass and power budgets are provided with an overview of the system design. The paper concludes with a discussion on the future applications enabled by CubeSat docking technologies, including the AAReST mission concept - a collaborative mission between the University of Surrey and CalTech and NASA JPL. Copyright © (2012) by the International Astronautical Federation.
Boshuizen CR, Marshall W, Bridges CP, Kenyon S, Klupar PD (2011) Learning to Follow: Embracing Commercial Technologies and Open Source for Space Missions Proceedings of the 62nd International Astronautical Congress 2011, (IAC ?11) (IAC-11-D4.2.5)
Kenyon S, Bridges CP, Liddle D, Dyer B, Parsons J, Feltham D, Taylor R, Mellor D, Schofield A, Lineham R, Long R, Fernandez J, Kadhem H, Davies P, Gebbie J, Holt N, Shaw P, Visage L, Theodorou T, Lappas VJ, Underwood CI (2011) STRaND-1: Use of a $500 smartphone as the central avionics of a nanosatellite
STRaND-1 is the first in a series of Surrey Satellite Technology Ltd. (SSTL)-Surrey Space Centre (SSC)
collaborative satellites designed for the purpose of technology path finding for future commercial operations. It is the
first time Surrey has entered the CubeSat field and differs from most CubeSats in that it will fly a modern
Commercial Off The Shelf (COTS) Android smartphone as a payload, along with a suite of advanced technologies
developed by the University of Surrey, and a payload from the University of Stellenbosch in South Africa. STRaND-
1 is also different in that anyone (not just from the space engineering or space science community) will be eligible to
fly their ?app" in space, for free. STRaND-1 is currently being manufactured and tested by volunteers in their own
free time, and will be ready for an intended launch in the first quarter of 2012.
This paper outlines the STRaND pathfinder programme philosophy which challenges some conventional space
engineering practises, and describes the impact of those changes on the satellite development lifecycle. The paper
then briefly describes the intent behind the design of STRaND-1, before presenting details on the design of the
nanosatellite, focussing of the details of the innovative new technologies. These technologies include two different
propulsion systems, an 802.11g WiFi experiment, a new VHF/UHF transceiver unit and a miniature 3-axis reaction
wheel assembly. The novel processing setup (which includes the smartphone) is discussed in some detail,
particularly the potential for outreach via the open source nature of Google's Android operating system. A stepthrough
of the planned concept of operations is provided, which includes a possible rendezvous and inspection
objective, demonstrating equal or improved capability compared to SNAP-1 with a reduced total system mass.
Finally, data from the test campaign is presented and compared against other notable CubeSats known for their
advanced capabilities. Rendered images of STRaND-1 are shown in Fig. I and are discussed later in the paper.
Kenyon S, Bridges CP, Liddle D, Dyer R, Parsons J, Feltham D, Taylor R, Mellor D, Schofield A, Linehan R (2011) STRaND-1: Use of a $500 Smartphone as the Central Avionics of a Nanosatellite Proceedings of the 2nd International Astronautical Congress 2011, (IAC ?11)
STRaND-1 is the first in a series of Surrey Satellite Technology Ltd. (SSTL)-Surrey Space Centre (SSC)
collaborative satellites designed for the purpose of technology path finding for future commercial operations. It is the
first time Surrey has entered the CubeSat field and differs from most CubeSats in that it will fly a modern
Commercial Off The Shelf (COTS) Android smartphone as a payload, along with a suite of advanced technologies
developed by the University of Surrey, and a payload from the University of Stellenbosch in South Africa. STRaND-
1 is also different in that anyone (not just from the space engineering or space science community) will be eligible to
fly their ?app" in space, for free. STRaND-1 is currently being manufactured and tested by volunteers in their own
free time, and will be ready for an intended launch in the first quarter of 2012.
This paper outlines the STRaND pathfinder programme philosophy which challenges some conventional space
engineering practises, and describes the impact of those changes on the satellite development lifecycle. The paper
then briefly describes the intent behind the design of STRaND-1, before presenting details on the design of the
nanosatellite, focussing of the details of the innovative new technologies. These technologies include two different
propulsion systems, an 802.11g WiFi experiment, a new VHF/UHF transceiver unit and a miniature 3-axis reaction
wheel assembly. The novel processing setup (which includes the smartphone) is discussed in some detail,
particularly the potential for outreach via the open source nature of Google's Android operating system. A stepthrough
of the planned concept of operations is provided, which includes a possible rendezvous and inspection
objective, demonstrating equal or improved capability compared to SNAP-1 with a reduced total system mass.
Finally, data from the test campaign is presented and compared against other notable CubeSats known for their
advanced capabilities. Rendered images of STRaND-1 are shown in Fig. I and are discussed later in the paper.
Vladimirova T, Wu XF, Bridges CP, Arslan T, Haridas N, Yang E, Erdogan AT, Barton N, Walton AJ, Thomson JS, Stoica A, McDonald-Maier KD, Howells WGJ (2006) Intelligent and Distributed Reconfigurable System-on-Chip Sensor Networks for Space Applications - An Introduction to ESPACENET A-260
Erlank AO, Bridges CP (2016) The Satellite Stem Cell Architecture
Low-cost satellites continue to grow in popularity
and capability, but have shown poor on-orbit performance to
date. While traditional satellite missions have relied upon expensive
fault prevention techniques, such as component screening, the
use of radiation hardened components, and extensive test campaigns,
low-cost missions must focus on fault tolerance, instead.
This paper describes a novel, fault-tolerant system architecture,
named Satellite Stem Cells. The Satellite Stem Cell Architecture,
which is based on artificial cells, evolved from research into
traditional reliability theory, bio-inspired engineering, and agentbased
computing. Traditional reliability theory points towards
k-out-of-n architectures for their superior reliability, while cell
biology demonstrates how to build extremely multifunctional
subsystems. Finally, agent computing provides a solution for
facilitating the cooperation of a set of autonomous cells in a
peer-to-peer environment. This paper describes the development
of the architecture, details the artificial cell design, and gives
preliminary implementation details
Bridges CP, Vladimirova T (2009) Agent Computing Applications in Distributed Satellite Systems ISADS 2009: 2009 INTERNATIONAL SYMPOSIUM ON AUTONOMOUS DECENTRALIZED SYSTEMS, PROCEEDINGS pp. 201-208
Bridges CP, Vladimirova T (2008) Dual core system-on-a-chip design to support inter-satellite communications PROCEEDINGS OF THE 2008 NASA/ESA CONFERENCE ON ADAPTIVE HARDWARE AND SYSTEMS pp. 191-198
Davidson RL, Bridges CP (2016) Adaptive Multispectral GPU Accelerated Architecture for Earth Observation Satellites 201 IEEE International Conference on Imaging Systems and Techniques (IST) Proceedings
In recent years the growth in quantity, diversity
and capability of Earth Observation (EO) satellites, has enabled
increase?s in the achievable payload data dimensionality and
volume. However, the lack of equivalent advancement in
downlink technology has resulted in the development of an
onboard data bottleneck. This bottleneck must be alleviated in
order for EO satellites to continue to efficiently provide high
quality and increasing quantities of payload data.
This research explores the selection and implementation of
state-of-the-art multidimensional image compression algorithms
and proposes a new onboard data processing architecture, to
help alleviate the bottleneck and increase the data throughput of
the platform. The proposed new system is based upon a
backplane architecture to provide scalability with different
satellite platform sizes and varying mission?s objectives. The
heterogeneous nature of the architecture allows benefits of both
Field Programmable Gate Array (FPGA) and Graphical
Processing Unit (GPU) hardware to be leveraged for maximised
data processing throughput.
Bridges C, Kenyon S, Underwood C, Lappas V (2011) STRaND-1: The world's first smartphone nanosatellite 2nd International Conference on Space Technology, ICST 2011
Space researchers at the University of Surrey and Surrey Satellite Technology Limited (SSTL) have developed 'STRaND-1', a satellite containing a smartphone payload that will be launched into orbit around the Earth later this year. STRaND-1 (Surrey Training, Research and Nanosatellite Demonstrator) is being developed by the Surrey team to demonstrate the advanced capabilities of a satellite built quickly using advanced commercial off-the-shelf components. The satellite will be launched into orbit around the Earth in 2011. The phone will run on Android's powerful open-source operating system. A powerful computer, built at the Surrey Space Centre, will test the vital statistics of the phone once in space. The computer will check which components of the phone are working normally and will relay images and messages back to Earth via a radio system. Once all the tests are complete, the plan is to switch off the micro computer and the smartphone will be used to operate parts of the satellite. The smartphone avionics suite is only one of the many technological advances packed into this 4kg satellite. To precisely point and manoeuvre, the satellite also incorporates advanced guidance, navigation and control systems. © 2011 IEEE.
Taylor BO, Duke R, Stewart B, Massimiani C, Djamane F, Bridges CP, Aglietti GS, Lassakeur A, Amine Ouisb M, Cherif Ladouze M, Meftah K, Underwood CI, Chikouche A, Hamed D (2017) AlSat-Nano: Knowledge Transfer to Operational Partnership 68th International Astronautical Congress Proceedings
The AlSat-Nano mission is a joint endeavour by the UK and Algeria to build and operate a 3U CubeSat. The project was designed to provide training to Algerian students, making use of UK engineering and experience. The CubeSat was designed and built by the Surrey Space Centre (SSC) of the University of Surrey and hosts three UK payloads with operations run by the Algerian Space Agency (ASAL). The educational and CubeSat development were funded by the UK Space Agency (UKSA), whilst the UK payloads were self-funded. Launch and operations are funded by ASAL. This paper illustrates the development of the programme, the engineering of the satellite and the development of collaborative operations between the SSC and ASAL.
Bridges CP, Vladimirova T (2013) Towards an agent computing platform for distributed computing on satellites IEEE Transactions on Aerospace and Electronic Systems 49 (3) pp. 1824-1838
Today's mobile devices and countless other embedded devices now aim to use networking technologies utilizing the latest electronics and software to provide new functions. Distributed satellite systems, seen to be analogous to mobile ad hoc networks (MANET), perform new mission functions with high mobility and intermittent connectivity that make satellite network management and operations difficult. New drivers and requirements are outlined for node and network levels in any given topology requiring real-time client-server or peer-to-peer (P2P) networking applications. To meet these requirements a novel agent computing platform (ACP) is proposed utilizing technologies from the multi-processor and agent middleware fields for real-time Java networking and mobile ad hoc network-based distributed computing applications at a minimal overhead to existing systems. The Java optimised processor (JOP) is investigated and embedded into an existing LEON3-based system-on-a-chip (SoC) design to provide a new fault-tolerant, parallel processing, and network functionalities. Agent middleware is discussed and compared for porting to the new dual processor design with a new middleware instance manager thread to enable software resets at runtime on the Java processor without halting the processor. After verification these two technologies are combined and discussed in depth to highlight key technological problems of this real-time ACP implementation.
Sorensen TC, Bergman JES, Saunders C, Gao Y, Lappas V, Liddle D, Mouginis-Mark P, Nunes MA, Palmer P, Underwood C, Bridges C (2014) Using a constellation of small satellites to characterize the RF quiescence of the lunar farside Proceedings of the International Astronautical Congress, IAC 6 pp. 4071-4083
Radio images of red-shifted 21-cm signals from neutral hydrogen originating from the very early Universe, the so-called Dark Ages before the first stars formed, are impossible to obtain from Earth due to man-made radio frequency interference (RFI) and the opacity of the ionosphere below
McKie R (2011) How Britain can rejoin the space race The Observer
With the space shuttle on the eve of its final mission, British companies are at the forefront of innovation to drive the next wave of space exploration
Erlank AO, Bridges CP (2017) Satellite Stem Cells: The Benefits and Overheads of Reliable, Multicellular Architectures Proceedings of 2017 IEEE Aerospace Conference
While small, low-cost satellites continue to increase in capability and popularity, their reliability remains a problem. Traditional techniques for increasing system reliability are well known to satellite developers, however, their implementation on low-cost satellites is often limited due to intrinsic mass, volume and budgetary restrictions. Aiming for graceful degeneration, therefore, may be a more promising route. To this end, a stem-cell-inspired, multicellular architecture is being developed using commercial-off-the-shelf components. It aims to replace a significant portion of a typical satellite?s bus avionics with a set of initially identical cells. Analogous to biological cells, the artificial cells are able to differentiate during runtime to take on a variety of tasks thanks to a set of artificial proteins. Each cell reconfigures its own proteins within the context of a system-wide distributed task management strategy. In this way, essential tasks can be maintained, even as system cells fail. This paper focusses on two hardware implementations of the stem-cell inspired architecture. The first implementation, based on a single cell, serves as the Payload Interface Computer on a CubeSat named SME-SAT. The second hardware implementation is a benchtop system composed of several cells intended to demonstrate a complete multicellular system in operation. In order to demonstrate the feasibility of these multicellular architectures, the physical attributes of the hardware implementations are compared to those of more traditional implementations and are shown to have enhanced reliability at the cost of increased power and internal bus bandwidth.
Maheshwarappa M, Bowyer M, Bridges CP (2017) Improvements in CPU & FPGA Performance for Small Satellite SDR Applications IEEE Transactions on Aerospace and Electronic Systems 53 (1) pp. 310-322
The ongoing evolution in constellation/formation of CubeSats along with steadily increasing number of satellites deployed in Lower Earth Orbit (LEO), demands a generic reconfigurable multimode communication platforms. As the number of satellites increase, the existing protocols combined with the trend to build one control station per CubeSat become a bottle neck for existing communication methods to support data volumes from these spacecraft at any given time. This paper explores the Software Defined Radio (SDR) architecture for the purposes of supporting multiple-signals from multiple-satellites, deploying mobile and/or distributed ground station nodes to increase the access time of the spacecraft and enabling a future SDR for Distributed Satellite Systems (DSS). Performance results of differing software transceiver blocks and the decoding success rates are analysed for varied symbol rates over different cores to inform on bottlenecks for Field Programmable Gate Array (FPGA) acceleration. Further, an embedded system architecture is proposed based on these results favouring the ground station which supports the transition from single satellite communication to multi-satellite communications.
Nezzari Y, Bridges CP (2017) Compiler Extensions towards Reliable Multicore Processors 2017 Aerospace Conference Proceedings
The current trend in commercial processors is producing multi-core architectures which pose both an opportunity and a challenge for future space based processing. The opportunity is how to leverage multi-core processors for high intensity computing applications and thus provide an order of magnitude increase in onboard processing capability with less size, mass, and power. The challenge is to provide the requisite safety and reliability in an extremely challenging radiation environment. The objective is to advance from multiple single processor systems typically flown to a fault tolerant multi-core system. Software based methods for multi-core processor fault tolerance to single event effects (SEEs) causing interrupts or ?bit-flips? are investigated and we propose to utilize additional cores and memory resources together with newly developed software protection techniques. This work also assesses the optimal trade space between reliability and performance. Our work is based on the modern compiler ?LLVM? as it is ported to many architectures, where we implement optimization passes that enable automatic addition of protection techniques including Nmodular redundancy (NMR) and error detection and correction (EDAC) at assembly/instruction level to languages supported. The optimization passes modify the intermediate representation of the source code meaning it could be applied for any high level language, and any processor architecture supported by the LLVM framework. In our initial experiments, we implement separately triple modular redundancy (TMR) and error detection and correction codes including (Hamming, BCH) at instruction level. We combine these two methods for critical applications, where we first TMR our instructions, and then use EDAC as a further measure, when TMR is not able to correct the errors originating from the SEE. Our initial experiments show good performance (about 10% overhead) when protecting the memory of code using double error detection single error correction hamming code and TMR (Triple modular redundancy), further work is needed to improve the performance when protecting the memory of code using the BCH code. This work would be highly valuable, both to satellites/space but also in general computing such as in in aircraft, automotive, server farms, and medical equipment (or anywhere that needs safety critical performance) as hardware gets smaller and more susceptible.
Davidson R, Bridges CP (2017) GPU Accelerated Multispectral EO Imagery Optimised CCSDS-123 Lossless Compression Implementation 2017 IEEE Aerospace Conference Proceedings
Continual advancements in Earth Observation (EO) optical imager payloads has led to a significant increase in the volume of multispectral data generated onboard EO satellites. As a result, a growing onboard data bottleneck need to be alleviated. One technique commonly used is onboard image compression. However, the performance of traditional space qualified processors, such as radiation hardened FPGAs, are not able to meet current nor future onboard data processing requirements. Therefore, a new high capability hardware architecture is required. In previous work a new GPU accelerated scalable heterogeneous hardware architecture for onboard data processing was proposed. In this paper, two new CUDA GPU implementations of the state-of-the-art lossless multidimensional image compression algorithm CCSDS-123, are discussed. The first implementation is a generic CUDA implementation of the CCSDS-123 algorithm whilst the second is optimised specifically for multispectral EO imagery. Both implementations utilise image tiling to leverage an additional axis for algorithm parallelisation to increase processing throughput. The CUDA implementation and optimisation techniques deployed are discussed in the paper. In addition, compression ratio and throughput performance results are presented for each implementation. Further experimental studies into the relationships between algorithm user definable compression parameters, tile sizes, tile dimensions and the achieved compression ratio and throughput, were performed.
Bartram P, Bridges C, Bowman D, Shirville G (2017) Software Defined Radio Baseband Processing for ESA ESEO Mission AMSAT Journal 2017 (Jul/Au) pp. 15-21
The European Student Earth
Orbiter (ESEO) is a micro-satellite mission
to low Earth orbit and is being developed,
integrated, and tested by European
university students as an ESA Education
Office project. AMSAT-UK and Surrey
Space Centre are contributing to the mission
with a transceiver and transponder similar
to that of FUNcube-1 with the addition
of utilising a Atmel AT32 processor for
packet software-redundancy, baseband
processing, forward error correction, and
packet forming; acting as a step towards
software defined radio using low MIPS
automotive microprocessors. As on the
FUNcube-1 satellite, the telemetry formats
and encoding schemes presented utilize a
large ground network of receivers on the
VHF downlink and conforms to 1200 bps
and a new 4800 bps redundant downlink
for the rest of the spacecraft. The uplink is
on L-band using bespoke partial-CCSDS
frames.
Bartram P, Bridges CP, Bowman D, Shirville G (2017) Software Defined Radio Baseband Processing for ESA ESEO Mission Proceedings of 2017 IEEE Aerospace Conference
The European Student Earth Orbiter (ESEO) is a micro-satellite mission to Low Earth Orbit and is being developed, integrated, and tested by European university students as an ESA Education Office project. AMSAT-UK and Surrey Space Centre are contributing to the mission with a transceiver and transponder similar to that of FUNcube-1 with the addition of utilising a Atmel AT32 processor for packet software-redundancy, baseband processing, forward error correction, and packet forming; acting as a step towards software defined radio using low MIPS automotive microprocessors. As on the FUNcube-1 satellite, the telemetry formats and encoding schemes presented utilize a large ground network of receivers on the VHF downlink and conforms to 1200 bps and a new 4800 bps redundant downlink for the rest of the spacecraft. The uplink is on L-band using bespoke partial-CCSDS frames. This paper details the flight software on the engineering and flight models to ESA, and the technical configuration and associated tests of demonstrating the processor load is under for varying operating and sampling modes. In particular, a key contribution will be the details of utilising the Google Test Suite for verification of the SDR functions and FreeRTOS tools to optimize processor load margins to 30% when operating parallelized ADC and DAC, and CAN-open telemetry chains and what memory considerations are needed to ensure stable long-term operations.
Eckersley S, Saunders C, Lobb D, Johnston G, Baud T, Sweeting MN, Underwood CI, Bridges CP, Chen R (2017) Future Rendezvous and Docking Missions enabled by low-cost but safety compliant Guidance Navigation and Control (GNC) architectures Proceedings of The 15th Reinventing Space Conference
Proximity flight systems for rendezvous-and-docking, are traditionally the domain of large, costly institutional
manned missions, which require extremely robust and expensive Guidance Navigation and Control (GNC) solutions.
By developing a low-cost and safety compliant GNC architecture and design methodology, low cost GNC solutions
needed for future missions with proximity flight phases will have reduced development risk, and more rapid
development schedules. This will enable a plethora of on-orbit services to be realised using low cost satellite
technologies, and lower the cost of the services to a point where they can be offered to commercial as well as
institutional entities and thereby dramatically grow the market for on-orbit construction, in-orbit servicing and active
debris removal. It will enable organisations such as SSTL to compete in an area previously exclusive to large
institutional players. The AAReST mission (to be launched in 2018), will demonstrate some key aspects of low cost
close proximity ?co-operative? rendezvous and docking (along with reconfiguration/control of multiple mirror
elements) for future modular telescopes. However this is only a very small scale academic mission demonstration
using cubesat technology, and is limited to very close range demonstrations.
This UK National Space Technology Programme (NSTP-2) project, which is being carried out by SSTL and SSC, is
due to be completed by the end of November 2017 and is co-funded by the UK Space Agency and company R&D. It
is aiming to build on the AAReST ("Autonomous Assembly of a Reconfigurable Space Telescope") mission (where
appropriate), and industrialise existing research, which will culminate in a representative model that can be used to
develop low-cost GNC solutions for many different mission applications that involve proximity activities, such as
formation flying, and rendezvous and docking. The main objectives and scope of this project are the following:
· Definition of a reference mission design (based on a scenario that SSTL considers credible as a realistic
scenario) and mission/system GNC requirements.
· Develop a GNC architectural design for low cost missions applications that involve close proximity
formation flying, rendezvous and docking (RDV&D) - i.e. ?proximity activities?
· Develop a low cost sensor suite suitable for use on proximity missions
· Consider possible regulatory constraints that may apply to the mission
The SSTL/SSC reference mission concept is a
Erlank A (2018) A multicellular architecture towards low-cost satellite reliability.
While small, low-cost satellites continue to increase in capability and popularity, their reliability remains a problem. Traditional techniques for increasing system reliability are well known to satellite developers. They include the use of radiation-hardened and screened components, extensive cold redundancy and thorough test campaigns. However, the implementation of these techniques on small, low-cost satellites is often limited due to intrinsic mass, volume and budgetary restrictions. Aiming for graceful degradation, therefore, may be a more promising route.

Inspired by the robustness of single-celled and multi-cellular biological organisms, bio-inspired computing systems, multi-agent systems, and modular spacecraft concepts, this work presents the design, implementation and analysis of an artificial, cell-based system architecture. Named the Satellite Stem Cell Architecture, the proposed system aims to replace a significant portion of a typical satellite?s bus avionics with a set of initially identical, mass produced, artificial cells. Analogous to their biological counterparts, the artificial cells can differentiate during runtime to take on a variety of tasks, thanks to a set of artificial proteins. Each cell reconfigures its own proteins within the context of a system-wide, distributed task management strategy. In this way, essential tasks can be maintained, even as system cells fail.

The Satellite Stem Cell Architecture differs from existing bio-inspired computing systems by extending the concept to include reconfigurable interfaces to real-world sensors and actuators, and by its inclusion of a set of middleware which turns each cell into a multi-agent platform. Furthermore, an emphasis is placed on practical applicability, with power consumption, volume and production cost driving the implementation. A detailed description of the artificial cell hardware, and multi-agent middleware, is given. Additionally, two CubeSat-scale, practical implementations of the architecture are described. While one, which forms the payload interface computer of the SMESAT CubeSat, demonstrates only a subset of the proposed multicellular features, the other is a full testbed based on two artificial cells of four proteins each.

To compare the reliability of the proposed architecture to traditional forms of redundancy, an analytical reliability equation is derived for predicting the lifetimes of multicellular systems. It is shown that determining the optimal configuration of proteins per cell and cells per system is complex, as different configurations are optimal during different phases of the mission lifetime. Nevertheless, a set of trends in system behaviour are discovered, which will prove useful to system designers. Using a purpose-developed, multicellular simulation environment, the results of the analytical work are verified, and further problems relating to peripheral interfaces and cross-strapping are investigated.

Finally, using measured characteristics of the implemented testbed and the derived analytical lifetime predictions, the Artificial Stem Cell Architecture is compared against traditional CubeSat and microsatellite avionics suites. The results show that the proposed architecture gives increasing reliability and performance benefits with increased scale, and that while its power consumption overheads make it prohibitive for implementation on CubeSats, it is well-suited to microsatellites.