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.2017.7943897
A. Babuscia, J. Sauder, A. Chandra, J. Thangavelautham, L. Feruglio, N. Bienert
Interplanetary1 CubeSats and small satellites have potential to provide means to explore space and to perform science in a more affordable way. As the goals for these spacecraft become more ambitious in space exploration, the communication systems currently implemented will need to be improved to support those missions. One of the bottlenecks is the antennas' size, due to the close relation between antenna gain and dimensions. Hence, a possible solution is to develop inflatable antennas which can be packaged efficiently, occupying a small amount of space, and they can provide, once deployed, large dish dimension and correspondent gain. A prototype of a 1 m inflatable antenna for X-Band has been developed in a joint effort between JPL and ASU. After initial photogrammetry tests and radiation tests, it was discovered that the design was not able to meet the required gain. As a result, a new design, based on a spherical inflatable membrane, is proposed. This new design will allow reaching a more stable inflatable surface, hence improving the electromagnetic performance. This paper will detail the principle challenges in developing this new antenna focusing on: design, EM analysis, fabrication and tests.
{"title":"Inflatable antenna for CubeSat: A new spherical design for increased X-band gain","authors":"A. Babuscia, J. Sauder, A. Chandra, J. Thangavelautham, L. Feruglio, N. Bienert","doi":"10.1109/AERO.2017.7943897","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943897","url":null,"abstract":"Interplanetary1 CubeSats and small satellites have potential to provide means to explore space and to perform science in a more affordable way. As the goals for these spacecraft become more ambitious in space exploration, the communication systems currently implemented will need to be improved to support those missions. One of the bottlenecks is the antennas' size, due to the close relation between antenna gain and dimensions. Hence, a possible solution is to develop inflatable antennas which can be packaged efficiently, occupying a small amount of space, and they can provide, once deployed, large dish dimension and correspondent gain. A prototype of a 1 m inflatable antenna for X-Band has been developed in a joint effort between JPL and ASU. After initial photogrammetry tests and radiation tests, it was discovered that the design was not able to meet the required gain. As a result, a new design, based on a spherical inflatable membrane, is proposed. This new design will allow reaching a more stable inflatable surface, hence improving the electromagnetic performance. This paper will detail the principle challenges in developing this new antenna focusing on: design, EM analysis, fabrication and tests.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"38 2 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":"125874789","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.2017.7943963
Pamela Wheeler, R. Cobb, C. Hartsfield, B. Prince
Space Situational Awareness (SSA) is of utmost importance in today's space dependent, congested and contested environment. The health of a propulsion system is vital to ensure proper function and thus proper mission placement. Electric propulsion is gaining popularity for satellite propulsion systems due to higher efficiencies, specific impulse, and the savings it offers in both spacecraft mass and launch costs. Electron temperature is a commonly used diagnostic to determine the efficiency of a Hall thruster. Recent papers have coordinated near infrared (NIR) spectral measurements of ionization lines in xenon and krypton to electron temperature measurements. This research will characterize NIR plume emissions for a 600 Watt Hall thruster using both xenon and krypton propellants for a variety of observation angles and operating power levels. By determining spectral differences when altering these variables, it would be possible to identify angle, power level, and propellant in order to provide information on electron temperature and thus efficiency. Although they have a high specific impulse, electric propulsion systems provide lower thrust than chemical alternatives. This means that the firing times needed for spacecraft maneuvers can be on the order of hours to months. This provides an opportunity for this characterization to not only be put to use in chamber experiments but on-orbit as well. Ground-based observations of these spectral lines would allow for identification of the type of thruster as well as the health of the system while the satellite is in operation on-orbit. The current SSA architecture is limited and task saturated. If smaller telescopes, like those at universities, could successfully detect these signatures they could augment data collection for the SSA network. To facilitate data collection, precise atmospheric modeling must be used to identify the signature. Within the atmosphere, the NIR has a higher transmission rate and typical HET propellants are approximately 3x the intensity in the NIR versus the visible spectrum making it ideal for ground based observations. This research will combine emission measurements with atmospheric and plume models to develop a single end-to-end model that will determine xenon and krypton signatures through the atmosphere, discernable differences in power level and viewing angle of Hall thruster systems, and estimate the efficacy through ground-based observations.
{"title":"Satellite propulsion spectral signature detection and analysis","authors":"Pamela Wheeler, R. Cobb, C. Hartsfield, B. Prince","doi":"10.1109/AERO.2017.7943963","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943963","url":null,"abstract":"Space Situational Awareness (SSA) is of utmost importance in today's space dependent, congested and contested environment. The health of a propulsion system is vital to ensure proper function and thus proper mission placement. Electric propulsion is gaining popularity for satellite propulsion systems due to higher efficiencies, specific impulse, and the savings it offers in both spacecraft mass and launch costs. Electron temperature is a commonly used diagnostic to determine the efficiency of a Hall thruster. Recent papers have coordinated near infrared (NIR) spectral measurements of ionization lines in xenon and krypton to electron temperature measurements. This research will characterize NIR plume emissions for a 600 Watt Hall thruster using both xenon and krypton propellants for a variety of observation angles and operating power levels. By determining spectral differences when altering these variables, it would be possible to identify angle, power level, and propellant in order to provide information on electron temperature and thus efficiency. Although they have a high specific impulse, electric propulsion systems provide lower thrust than chemical alternatives. This means that the firing times needed for spacecraft maneuvers can be on the order of hours to months. This provides an opportunity for this characterization to not only be put to use in chamber experiments but on-orbit as well. Ground-based observations of these spectral lines would allow for identification of the type of thruster as well as the health of the system while the satellite is in operation on-orbit. The current SSA architecture is limited and task saturated. If smaller telescopes, like those at universities, could successfully detect these signatures they could augment data collection for the SSA network. To facilitate data collection, precise atmospheric modeling must be used to identify the signature. Within the atmosphere, the NIR has a higher transmission rate and typical HET propellants are approximately 3x the intensity in the NIR versus the visible spectrum making it ideal for ground based observations. This research will combine emission measurements with atmospheric and plume models to develop a single end-to-end model that will determine xenon and krypton signatures through the atmosphere, discernable differences in power level and viewing angle of Hall thruster systems, and estimate the efficacy through ground-based observations.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"54 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":"121107681","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.2017.7943866
M. Pugh, I. Kuperman, Fernando H. Aguirre, H. Mojaradi, Carl Spurgers, M. Kobayashi, E. Satorius, T. Jedrey
The Universal Space Transponder (UST) is a next generation transponder developed at the Jet Propulsion Laboratory to meet a large variety of telecom, navigation, and radio science needs for future deep-space and near-Earth missions. This paper details the UST software defined radio design and describes how the combination of a modular hardware architecture and in-flight reprogrammability enables a new level of flexibility and expandability for a space transponder. The UST uses common power and digital processing assemblies that can be integrated with a variety of RF modules and is capable of simultaneous, multiband operations with data rates up to 37.5 Mbps RX and 300 Mbps TX. This allows a single radio to support all the direct-to-Earth and relay communication requirements for even complex mission scenarios, reducing the total cost, mass, and power. The discussion includes a description of the current UST engineering models that have been built and tested, as well as details about the next generation capabilities supported by UST, including advanced link coding and modulation, radiometric techniques, and in-radio protocol handling. Details are also presented on RF modules and digital processing in development for radio science and astronomy purposes, including a bistatic radar receiver and broadband planetary emissions receiver. These will demonstrate the ability to integrate low-cost science instruments into the UST architecture, further expanding the versatility of the UST.
{"title":"The Universal Space Transponder: A next generation software defined radio","authors":"M. Pugh, I. Kuperman, Fernando H. Aguirre, H. Mojaradi, Carl Spurgers, M. Kobayashi, E. Satorius, T. Jedrey","doi":"10.1109/AERO.2017.7943866","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943866","url":null,"abstract":"The Universal Space Transponder (UST) is a next generation transponder developed at the Jet Propulsion Laboratory to meet a large variety of telecom, navigation, and radio science needs for future deep-space and near-Earth missions. This paper details the UST software defined radio design and describes how the combination of a modular hardware architecture and in-flight reprogrammability enables a new level of flexibility and expandability for a space transponder. The UST uses common power and digital processing assemblies that can be integrated with a variety of RF modules and is capable of simultaneous, multiband operations with data rates up to 37.5 Mbps RX and 300 Mbps TX. This allows a single radio to support all the direct-to-Earth and relay communication requirements for even complex mission scenarios, reducing the total cost, mass, and power. The discussion includes a description of the current UST engineering models that have been built and tested, as well as details about the next generation capabilities supported by UST, including advanced link coding and modulation, radiometric techniques, and in-radio protocol handling. Details are also presented on RF modules and digital processing in development for radio science and astronomy purposes, including a bistatic radar receiver and broadband planetary emissions receiver. These will demonstrate the ability to integrate low-cost science instruments into the UST architecture, further expanding the versatility of the UST.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"1 11 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":"129213834","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.2017.7943587
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.
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