Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943598
M. Langer, M. Weisgerber, J. Bouwmeester, A. Hoehn
For many years, traditional satellite design philosophy was dominated by highly reliable components, conservative designs and extensive performance testing at subsystem and integrated system levels to achieve long lifetimes in the harsh space environment. CubeSats attempted to choose a different philosophy, utilizing suitable state-of the art, commercial-off-the shelf products, yielding, if successful, an increased performance per mass figure of merit for those small vessels at potentially higher risk but lower cost. CubeSats seemed to promise universities and companies to be faster, better and cheaper — once more in history. Unfortunately, many CubeSat missions, especially university-built ones, never achieved a detectable functional state or failed shortly after the satellites were ejected from their deployer. Data based on our developed CubeSat Failure Database (CFD) and research carried out by others suggest, that a great percentage of those early failure cases could have been detected and avoided by more careful and adequate system-level functional testing on the ground. However, many university teams still fail to plan with adequate resources for system level functional testing or are confronted with hard deadlines, thus unable to complete appropriate integrated system testing on a sufficient level, and launching a satellite that never was adequately functional. Ongoing work on a novel reliability estimation tool using Bayesian methods is introduced to fill this gap and to provide meaningful data for all developers on the achievable reliability and required functional testing time of their CubeSats. Using test data and reliability goals for their actual mission, merging that data with statistical data from past missions and a database of subjective developer's beliefs, CubeSat developers should now be able to estimate their required functional testing time on subsystem and system level at an early project stage, as a function of the targeted reliability goal for their CubeSat. Alternatively, if the required resources (testing time, money, knowledge) are not available, CubeSat developers and program managers can still use the tool to now quantify a resulting realistic lower boundary for the expected system reliability of the mission, and decide, if their mission goals can be fulfilled or not with a certain probability. To evolve CubeSats into more reliable and accepted platforms for scientific payloads and commercial applications, it is utmost important to avoid or reduce the many infant mortality cases, where no or little useful data is produced by the satellite. To guide developers towards higher success rates without losing the spirit of using novel, state of the art technology in fast mission timelines, the reliability estimation tool should ensure higher reliability of CubeSat missions without drawing too much resources nor imposing too many burdens on the CubeSat teams.
{"title":"A reliability estimation tool for reducing infant mortality in Cubesat missions","authors":"M. Langer, M. Weisgerber, J. Bouwmeester, A. Hoehn","doi":"10.1109/AERO.2017.7943598","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943598","url":null,"abstract":"For many years, traditional satellite design philosophy was dominated by highly reliable components, conservative designs and extensive performance testing at subsystem and integrated system levels to achieve long lifetimes in the harsh space environment. CubeSats attempted to choose a different philosophy, utilizing suitable state-of the art, commercial-off-the shelf products, yielding, if successful, an increased performance per mass figure of merit for those small vessels at potentially higher risk but lower cost. CubeSats seemed to promise universities and companies to be faster, better and cheaper — once more in history. Unfortunately, many CubeSat missions, especially university-built ones, never achieved a detectable functional state or failed shortly after the satellites were ejected from their deployer. Data based on our developed CubeSat Failure Database (CFD) and research carried out by others suggest, that a great percentage of those early failure cases could have been detected and avoided by more careful and adequate system-level functional testing on the ground. However, many university teams still fail to plan with adequate resources for system level functional testing or are confronted with hard deadlines, thus unable to complete appropriate integrated system testing on a sufficient level, and launching a satellite that never was adequately functional. Ongoing work on a novel reliability estimation tool using Bayesian methods is introduced to fill this gap and to provide meaningful data for all developers on the achievable reliability and required functional testing time of their CubeSats. Using test data and reliability goals for their actual mission, merging that data with statistical data from past missions and a database of subjective developer's beliefs, CubeSat developers should now be able to estimate their required functional testing time on subsystem and system level at an early project stage, as a function of the targeted reliability goal for their CubeSat. Alternatively, if the required resources (testing time, money, knowledge) are not available, CubeSat developers and program managers can still use the tool to now quantify a resulting realistic lower boundary for the expected system reliability of the mission, and decide, if their mission goals can be fulfilled or not with a certain probability. To evolve CubeSats into more reliable and accepted platforms for scientific payloads and commercial applications, it is utmost important to avoid or reduce the many infant mortality cases, where no or little useful data is produced by the satellite. To guide developers towards higher success rates without losing the spirit of using novel, state of the art technology in fast mission timelines, the reliability estimation tool should ensure higher reliability of CubeSat missions without drawing too much resources nor imposing too many burdens on the CubeSat teams.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117351738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943786
Clara O’Farrell, Suman Muppidi, Joseph M. Brock, John W. Van Norman, I. Clark
The Advanced Supersonic Parachute Inflation Research and Experiments (ASPIRE) project will investigate the supersonic deployment, inflation, and aerodynamics of Disk-Gap-Band (DGB) parachutes in the wake of a slender body. The parachutes will be full-scale versions of the DGBs used by the Mars Science Laboratory in 2012 and planned for NASA's Mars 2020 project and will be delivered to targeted deployment conditions representative of flight at Mars by sounding rockets launched out of NASA's Wallops Flight Facility. The parachutes will be tested in the wake of a slender payload whose diameter is approximately a sixth that of entry capsules used for Mars missions. Models of the deployment, inflation, and aerodynamic performance of the parachutes are necessary to design key aspects of the experiment, including: determining the expected loads and applicable margins on the parachute and payload; guiding sensor selection and placement; evaluating the vehicle trajectory for targeting, range safety, and recovery operations. In addition, knowledge of the differences in the behavior of the parachutes in the wake of slender and blunt bodies is required in order to interpret the results of the sounding rocket experiment and determine how they relate to expected performance behind blunt bodies at Mars. However, modeling the performance of a supersonic DGB in the wake of a slender body is challenging due to the scarcity of historical test data and modeling precedents. This paper describes the models of the aerodynamic performance of DGBs in supersonic slender-body wakes being developed for the ASPIRE sounding rocket test campaign. Development of these models is based on the four available flight tests of DGBs deployed in supersonic slender-body wakes as well as on data from past flight and wind-tunnel experiments of DGBs deployed in the wake of blunt bodies, on the reconstructed at-Mars DGB performance during past missions, and on computational fluid dynamics simulations. Simulations of the wakes of blunt and slender bodies in supersonic flow have been conducted in order to investigate the differences in the flowfields encountered by parachutes deployed in both wake types. The simulations have allowed the project to investigate the fundamental differences between the sounding rocket tests and the flight of a DGB during a Mars mission and to assess the limitations of the sounding rocket test architecture for evaluating flight performance at Mars.
{"title":"Development of models for disk-gap-band parachutes deployed supersonically in the wake of a slender body","authors":"Clara O’Farrell, Suman Muppidi, Joseph M. Brock, John W. Van Norman, I. Clark","doi":"10.1109/AERO.2017.7943786","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943786","url":null,"abstract":"The Advanced Supersonic Parachute Inflation Research and Experiments (ASPIRE) project will investigate the supersonic deployment, inflation, and aerodynamics of Disk-Gap-Band (DGB) parachutes in the wake of a slender body. The parachutes will be full-scale versions of the DGBs used by the Mars Science Laboratory in 2012 and planned for NASA's Mars 2020 project and will be delivered to targeted deployment conditions representative of flight at Mars by sounding rockets launched out of NASA's Wallops Flight Facility. The parachutes will be tested in the wake of a slender payload whose diameter is approximately a sixth that of entry capsules used for Mars missions. Models of the deployment, inflation, and aerodynamic performance of the parachutes are necessary to design key aspects of the experiment, including: determining the expected loads and applicable margins on the parachute and payload; guiding sensor selection and placement; evaluating the vehicle trajectory for targeting, range safety, and recovery operations. In addition, knowledge of the differences in the behavior of the parachutes in the wake of slender and blunt bodies is required in order to interpret the results of the sounding rocket experiment and determine how they relate to expected performance behind blunt bodies at Mars. However, modeling the performance of a supersonic DGB in the wake of a slender body is challenging due to the scarcity of historical test data and modeling precedents. This paper describes the models of the aerodynamic performance of DGBs in supersonic slender-body wakes being developed for the ASPIRE sounding rocket test campaign. Development of these models is based on the four available flight tests of DGBs deployed in supersonic slender-body wakes as well as on data from past flight and wind-tunnel experiments of DGBs deployed in the wake of blunt bodies, on the reconstructed at-Mars DGB performance during past missions, and on computational fluid dynamics simulations. Simulations of the wakes of blunt and slender bodies in supersonic flow have been conducted in order to investigate the differences in the flowfields encountered by parachutes deployed in both wake types. The simulations have allowed the project to investigate the fundamental differences between the sounding rocket tests and the flight of a DGB during a Mars mission and to assess the limitations of the sounding rocket test architecture for evaluating flight performance at Mars.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133567069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943981
T. Cichan, S. Bailey, S. Norris, R. Chambers, S. Jolly, J. Ehrlich
Orion, the Multi-Purpose Crew Vehicle, is a key piece of the NASA human exploration architecture for beyond earth orbit (BEO). Lockheed Martin was awarded the contracts for the design, development, test, and production for Orion up through the Exploration Mission 2 (EM-2). Lockheed Martin is also working on defining the cis-lunar Proving Ground mission architecture, in partnership with NASA. In addition, Lockheed Martin is exploring the definition of Mars missions as the horizon goal to provide input to the plans for human exploration of the solar system. This paper describes an architecture to determine the feasibility of a Mars Base Camp architecture within about a decade. This architecture would involve human exploration of both Martian moons, and provide an opportunity for the crew to interact with pre-staged robotic assets on Mars. This study is a high-level assessment to identify architecture drivers and science opportunities. There are several key tenets for this architecture. For this first human interplanetary mission, system redundancy and a self-rescue capability is required. The number of system developments is minimized, and the use of the already developed systems like the Space Launch System and Orion is maximized. To minimize the number of events that could lead to the loss of the whole crew, the architecture does not require rendezvous and docking of pre-staged elements necessary for crew survival during the mission. This paper will describe the different enabling technologies required. The trajectory assumptions will be described, including the results of studies performed for the transit to Mars and return to Earth, in addition to mission design trades for the exploration of the Martian system. The transfer vehicle module design concept will be detailed. Possible science activities will be described. Study results for propulsion technology, assembly methods, and the mission campaign will also be addressed, as well as a discussion of planned forward work. The results of this architecture study will show that a near term Mars mission is compelling and feasible, and will highlight the required key systems.
{"title":"Mars Base Camp: An architecture for sending humans to Mars by 2028","authors":"T. Cichan, S. Bailey, S. Norris, R. Chambers, S. Jolly, J. Ehrlich","doi":"10.1109/AERO.2017.7943981","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943981","url":null,"abstract":"Orion, the Multi-Purpose Crew Vehicle, is a key piece of the NASA human exploration architecture for beyond earth orbit (BEO). Lockheed Martin was awarded the contracts for the design, development, test, and production for Orion up through the Exploration Mission 2 (EM-2). Lockheed Martin is also working on defining the cis-lunar Proving Ground mission architecture, in partnership with NASA. In addition, Lockheed Martin is exploring the definition of Mars missions as the horizon goal to provide input to the plans for human exploration of the solar system. This paper describes an architecture to determine the feasibility of a Mars Base Camp architecture within about a decade. This architecture would involve human exploration of both Martian moons, and provide an opportunity for the crew to interact with pre-staged robotic assets on Mars. This study is a high-level assessment to identify architecture drivers and science opportunities. There are several key tenets for this architecture. For this first human interplanetary mission, system redundancy and a self-rescue capability is required. The number of system developments is minimized, and the use of the already developed systems like the Space Launch System and Orion is maximized. To minimize the number of events that could lead to the loss of the whole crew, the architecture does not require rendezvous and docking of pre-staged elements necessary for crew survival during the mission. This paper will describe the different enabling technologies required. The trajectory assumptions will be described, including the results of studies performed for the transit to Mars and return to Earth, in addition to mission design trades for the exploration of the Martian system. The transfer vehicle module design concept will be detailed. Possible science activities will be described. Study results for propulsion technology, assembly methods, and the mission campaign will also be addressed, as well as a discussion of planned forward work. The results of this architecture study will show that a near term Mars mission is compelling and feasible, and will highlight the required key systems.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"15 11","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133616266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943952
P. Bartram, C. Bridges, D. Bowman, G. Shirville
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.
欧洲学生地球轨道卫星(ESEO)是一个低地球轨道的微型卫星任务，作为欧空局教育办公室的一个项目，正在由欧洲大学生开发、集成和测试。AMSAT-UK和萨里空间中心为该任务提供了类似于FUNcube-1的收发器和应答器，并增加了利用Atmel AT32处理器进行包软件冗余、基带处理、前向纠错和包形成;作为使用低MIPS汽车微处理器的软件定义无线电的一步。与FUNcube-1卫星一样，所提出的遥测格式和编码方案利用VHF下行链路上的大型地面接收器网络，并符合1200 bps和用于航天器其余部分的新的4800 bps冗余下行链路。上行链路在l波段，使用定制的部分ccsds帧。本文详细介绍了ESA工程和飞行模型上的飞行软件，以及在不同操作和采样模式下显示处理器负载的技术配置和相关测试。特别是，一个关键的贡献将是利用Google Test Suite来验证SDR功能和FreeRTOS工具的细节，以优化并行ADC和DAC时的处理器负载余量到30%，以及can开放遥测链，以及需要哪些内存考虑来确保稳定的长期运行。
{"title":"Software defined radio baseband processing for ESA ESEO mission","authors":"P. Bartram, C. Bridges, D. Bowman, G. Shirville","doi":"10.1109/AERO.2017.7943952","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943952","url":null,"abstract":"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.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"258 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132715284","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943926
R. Kerczewski, J. Griner, W. Bishop, D. Matolak, Jeffrey D. Wilson
In order to provide for the safe integration of unmanned aircraft systems (UAS) into the National Airspace System, the control and non-payload communications (CNPC) link connecting the ground-based pilot with the unmanned aircraft must be highly reliable and robust, based upon standards that enable certification. Both line-of-sight (LOS) links using terrestrial-based communications and beyond-line-of-sight (BLOS) links using satellite communications are required to support UAS operations. The development of standards has been undertaken by RTCA Special Committee 228 (SC-228), with supporting technical data developed by NASA under the UAS in the National Airspace (NAS) Project. As a result of this work minimum operational performance standards (MOPS) have been completed and published for the LOS CNPC system. The second phase of work, for both NASA and RTCA involves the BLOS CNPC systems. The development of technical data to support MOPS development for UAS BLOS satellite-based CNPC links has now been initiated by NASA, and RTCA SC-228 has organized itself to begin the MOPS development process. This paper will provide an overview of the work that has been completed to date by the Communications Subproject in support of LOS C2 communications for UAS followed by an update of plans and progress for the BLOS phase of the project, with the focus on the UAS C2 spectrum aspects.
{"title":"Progress on the development of the UAS C2 link and supporting spectrum — from LOS to BLOS","authors":"R. Kerczewski, J. Griner, W. Bishop, D. Matolak, Jeffrey D. Wilson","doi":"10.1109/AERO.2017.7943926","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943926","url":null,"abstract":"In order to provide for the safe integration of unmanned aircraft systems (UAS) into the National Airspace System, the control and non-payload communications (CNPC) link connecting the ground-based pilot with the unmanned aircraft must be highly reliable and robust, based upon standards that enable certification. Both line-of-sight (LOS) links using terrestrial-based communications and beyond-line-of-sight (BLOS) links using satellite communications are required to support UAS operations. The development of standards has been undertaken by RTCA Special Committee 228 (SC-228), with supporting technical data developed by NASA under the UAS in the National Airspace (NAS) Project. As a result of this work minimum operational performance standards (MOPS) have been completed and published for the LOS CNPC system. The second phase of work, for both NASA and RTCA involves the BLOS CNPC systems. The development of technical data to support MOPS development for UAS BLOS satellite-based CNPC links has now been initiated by NASA, and RTCA SC-228 has organized itself to begin the MOPS development process. This paper will provide an overview of the work that has been completed to date by the Communications Subproject in support of LOS C2 communications for UAS followed by an update of plans and progress for the BLOS phase of the project, with the focus on the UAS C2 spectrum aspects.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133284669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943714
Y. Nezzari, C. Bridges
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 N-modular 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.
{"title":"Compiler extensions towards reliable multicore processors","authors":"Y. Nezzari, C. Bridges","doi":"10.1109/AERO.2017.7943714","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943714","url":null,"abstract":"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 N-modular 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.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129003115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943587
Randolph P. Lillard, J. Olejniczak
This paper presents the results of a NASA initiated Agency-wide assessment to better characterize the risks and potential mitigation approaches associated with landing human class payloads on Mars. Due to the criticality and long-lead nature of advancing Entry, Descent, and Landing (EDL) techniques, it is necessary to determine an appropriate strategy to improve the capability to land large payloads. A key focus of this study was to understand the key EDL risks with a focus on determining what “must” be tested at Mars. This process identified the various risks and potential risk mitigation strategies, along with the required key near-term technology development efforts and in what environment those technology demonstrations were best suited. The study identified key risks along with advantages to each entry technology. In addition, it was determined that with the EDL concept of operations (con ops) which minimized large scale transition events during entry, there was no technology requirement for a Mars pre-cursor demonstration as a necessary risk-mitigation test. Instead, NASA should take a direct path to a human-scale lander.
{"title":"Human Mars EDL pathfinder study: Assessment of technology development gaps and mitigations","authors":"Randolph P. Lillard, J. Olejniczak","doi":"10.1109/AERO.2017.7943587","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943587","url":null,"abstract":"This paper presents the results of a NASA initiated Agency-wide assessment to better characterize the risks and potential mitigation approaches associated with landing human class payloads on Mars. Due to the criticality and long-lead nature of advancing Entry, Descent, and Landing (EDL) techniques, it is necessary to determine an appropriate strategy to improve the capability to land large payloads. A key focus of this study was to understand the key EDL risks with a focus on determining what “must” be tested at Mars. This process identified the various risks and potential risk mitigation strategies, along with the required key near-term technology development efforts and in what environment those technology demonstrations were best suited. The study identified key risks along with advantages to each entry technology. In addition, it was determined that with the EDL concept of operations (con ops) which minimized large scale transition events during entry, there was no technology requirement for a Mars pre-cursor demonstration as a necessary risk-mitigation test. Instead, NASA should take a direct path to a human-scale lander.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124217811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943579
Andreas Iliopoulos, C. Enneking, Omar García Crespillo, T. Jost, S. Thoelert, F. Antreich
GNSS signals may present anomalies that degrade the positioning performance of GNSS receivers. Signal Quality Monitoring (SQM) is normally used to detect and to characterize these anomalies. This is required for the GNSS operators and integrity services to determine when a satellite should be considered as faulty and draw conclusions about the type of the fault. In this paper, we present a new SQM algorithm that tracks the GNSS signal and possible channel deformations by using a novel methodology based on the Extended Kalman Filter (EKF). The EKF is designed such that the measurement update is performed in post-correlation and using multiple correlators. After the estimation of the channel response, we add a detection step to determine if the channel deviates from the nominal signal transmission scenario (i.e., the single path propagation). Results suggests that the performance of the delay estimation with the proposed EKF structure outperforms the classical Delay-Locked-Loop (DLL) estimation, especially in the presence of distortions. Furthermore, it can reliably detect anomalous signal deformations as specified by ICAO threat model.
{"title":"Multicorrelator signal tracking and signal quality monitoring for GNSS with extended Kalman filter","authors":"Andreas Iliopoulos, C. Enneking, Omar García Crespillo, T. Jost, S. Thoelert, F. Antreich","doi":"10.1109/AERO.2017.7943579","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943579","url":null,"abstract":"GNSS signals may present anomalies that degrade the positioning performance of GNSS receivers. Signal Quality Monitoring (SQM) is normally used to detect and to characterize these anomalies. This is required for the GNSS operators and integrity services to determine when a satellite should be considered as faulty and draw conclusions about the type of the fault. In this paper, we present a new SQM algorithm that tracks the GNSS signal and possible channel deformations by using a novel methodology based on the Extended Kalman Filter (EKF). The EKF is designed such that the measurement update is performed in post-correlation and using multiple correlators. After the estimation of the channel response, we add a detection step to determine if the channel deviates from the nominal signal transmission scenario (i.e., the single path propagation). Results suggests that the performance of the delay estimation with the proposed EKF structure outperforms the classical Delay-Locked-Loop (DLL) estimation, especially in the presence of distortions. Furthermore, it can reliably detect anomalous signal deformations as specified by ICAO threat model.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"89 Pt B 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116293604","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943700
Cherice Moore, Randall Svetlik, Antony Williams
National Aeronautics and Space Administration (NASA) uses exercise countermeasures on the International Space Station (ISS) to maintain crew health and combat the negative effects of long-duration spaceflight on the human body. Most ISS exercise countermeasures system (CMS) equipment rely heavily on the use of textile and wire ropes to transmit resistive loads and provide stability in a microgravity environment. For a variety of reasons, including challenges in simulating microgravity environments for testing and limits on time available for life cycle testing, the textiles and wire ropes have contributed significantly to on-orbit planned and unplanned maintenance time. As a result, continued ground testing and on-orbit experience since the first expedition on the ISS in 2000 provide valuable data and lessons learned in materials selection, applications, and design techniques to increase service life of these ropes. This paper will present a review of the development and failure history of textile and wire ropes for four exercise countermeasure systems — the Treadmill with Vibration Isolation and Stabilization (TVIS) System, Cycle Ergometer with Vibration Isolation and Stabilization (CEVIS) System, Interim Resistive Exercise Device (IRED), and the Advanced Resistive Exercise Device (ARED) — to identify lessons learned in order to improve future systems. These lessons learned, paired with thorough testing on the ground, offer a forward path towards reduced maintenance time and up-mass for future space missions.
{"title":"Practical applications of cables and ropes in the ISS countermeasures system","authors":"Cherice Moore, Randall Svetlik, Antony Williams","doi":"10.1109/AERO.2017.7943700","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943700","url":null,"abstract":"National Aeronautics and Space Administration (NASA) uses exercise countermeasures on the International Space Station (ISS) to maintain crew health and combat the negative effects of long-duration spaceflight on the human body. Most ISS exercise countermeasures system (CMS) equipment rely heavily on the use of textile and wire ropes to transmit resistive loads and provide stability in a microgravity environment. For a variety of reasons, including challenges in simulating microgravity environments for testing and limits on time available for life cycle testing, the textiles and wire ropes have contributed significantly to on-orbit planned and unplanned maintenance time. As a result, continued ground testing and on-orbit experience since the first expedition on the ISS in 2000 provide valuable data and lessons learned in materials selection, applications, and design techniques to increase service life of these ropes. This paper will present a review of the development and failure history of textile and wire ropes for four exercise countermeasure systems — the Treadmill with Vibration Isolation and Stabilization (TVIS) System, Cycle Ergometer with Vibration Isolation and Stabilization (CEVIS) System, Interim Resistive Exercise Device (IRED), and the Advanced Resistive Exercise Device (ARED) — to identify lessons learned in order to improve future systems. These lessons learned, paired with thorough testing on the ground, offer a forward path towards reduced maintenance time and up-mass for future space missions.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"2016 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127271798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943666
M. Lingenauber, Klaus H. Strobl, N. Oumer, Simon Kriegel
This paper discusses the potential benefits of plenoptic cameras for robot vision during on-orbit servicing missions. Robot vision is essential for the accurate and reliable positioning of a robotic arm with millimeter accuracy during tasks such as grasping, inspection or repair that are performed in close range to a client satellite. Our discussion of the plenoptic camera technology provides an overview of the conceptional advantages for robot vision with regard to the conditions during an on-orbit servicing mission. A plenoptic camera, also known as light field camera, is basically a conventional camera system equipped with an additional array of lenslets, the micro lens array, at a distance of a few micrometers in front of the camera sensor. Due to the micro lens array it is possible to record not only the incidence location of a light ray but also its incidence direction on the sensor, resulting in a 4-D data set known as a light field. The 4-D light field allows to derive regular 2-D intensity images with a significantly extended depth of field compared to a conventional camera. This results in a set of advantages, such as software based refocusing or increased image quality in low light conditions due to recording with an optimal aperture while maintaining an extended depth of field. Additionally, the parallax between corresponding lenslets allows to derive 3-D depth images from the same light field and therefore to substitute a stereo vision system with a single camera. Given the conceptual advantages, we investigate what can be expected from plenoptic cameras during close range robotic operations in the course of an on-orbit servicing mission. This includes topics such as image quality, extension of the depth of field, 3-D depth map generation and low light capabilities. Our discussion is backed by image sequences for an on-orbit servicing scenario that were recorded in a representative laboratory environment with simulated in-orbit illumination conditions. We mounted a plenoptic camera on a robot arm and performed an approach trajectory from up to 2 m towards a full-scale satellite mockup. Using these images, we investigated how the light field processing performs, e.g. in terms of depth of field extension, image quality and depth estimation. We were also able to show the applicability of images derived from light fields for the purpose of the visual based pose estimation of a target point.
{"title":"Benefits of plenoptic cameras for robot vision during close range on-orbit servicing maneuvers","authors":"M. Lingenauber, Klaus H. Strobl, N. Oumer, Simon Kriegel","doi":"10.1109/AERO.2017.7943666","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943666","url":null,"abstract":"This paper discusses the potential benefits of plenoptic cameras for robot vision during on-orbit servicing missions. Robot vision is essential for the accurate and reliable positioning of a robotic arm with millimeter accuracy during tasks such as grasping, inspection or repair that are performed in close range to a client satellite. Our discussion of the plenoptic camera technology provides an overview of the conceptional advantages for robot vision with regard to the conditions during an on-orbit servicing mission. A plenoptic camera, also known as light field camera, is basically a conventional camera system equipped with an additional array of lenslets, the micro lens array, at a distance of a few micrometers in front of the camera sensor. Due to the micro lens array it is possible to record not only the incidence location of a light ray but also its incidence direction on the sensor, resulting in a 4-D data set known as a light field. The 4-D light field allows to derive regular 2-D intensity images with a significantly extended depth of field compared to a conventional camera. This results in a set of advantages, such as software based refocusing or increased image quality in low light conditions due to recording with an optimal aperture while maintaining an extended depth of field. Additionally, the parallax between corresponding lenslets allows to derive 3-D depth images from the same light field and therefore to substitute a stereo vision system with a single camera. Given the conceptual advantages, we investigate what can be expected from plenoptic cameras during close range robotic operations in the course of an on-orbit servicing mission. This includes topics such as image quality, extension of the depth of field, 3-D depth map generation and low light capabilities. Our discussion is backed by image sequences for an on-orbit servicing scenario that were recorded in a representative laboratory environment with simulated in-orbit illumination conditions. We mounted a plenoptic camera on a robot arm and performed an approach trajectory from up to 2 m towards a full-scale satellite mockup. Using these images, we investigated how the light field processing performs, e.g. in terms of depth of field extension, image quality and depth estimation. We were also able to show the applicability of images derived from light fields for the purpose of the visual based pose estimation of a target point.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"417 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124187562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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