Pub Date : 2010-03-06DOI: 10.1109/AERO.2010.5446939
Joseph Kim, E. Grayver, Jiayu Chen, Daniel Thai
Advanced communications satellite systems provide packet-switched high-speed transport services for various user applications, ranging from data services to imagery, voice, and video. Satellite uplinks and downlinks may experience various channel fades due to weather, blockages, terrestrial multipath, or jamming. A suite of mitigation techniques have been proposed to mitigate the wide range of channel impairments and optimize the use of available spectrum to deliver the highest possible data rate while satisfying quality of service (QoS) requirements. These techniques include channel interleaving and forward error correction (FEC) in the physical layer, dynamic coding and modulation (DCM) and automatic repeat request (ARQ) in the data link layer, prioritized packet forwarding in the network layer, and application codec adaptation (ACA) in the application layer. Since each mitigation strategy could potentially interact between layers, it is essential not only to assess the performance of each mitigation technique, but also to understand how multiple techniques work together. 12 This paper describes an emulation study of channel impairment mitigation using a combination of DCM, absolute priority scheduler (APS), and ACA. This is a continuation of our cross-layer mitigation studies previously published in [1,2]. Multiple video streams in different priorities were employed to demonstrate how underlying mitigation techniques work together to preserve the QoS of multiple applications under various channel fades. This paper presents the test bed architecture, mitigation techniques, test configurations, and test results.
{"title":"Quality of service provision under channel fading","authors":"Joseph Kim, E. Grayver, Jiayu Chen, Daniel Thai","doi":"10.1109/AERO.2010.5446939","DOIUrl":"https://doi.org/10.1109/AERO.2010.5446939","url":null,"abstract":"Advanced communications satellite systems provide packet-switched high-speed transport services for various user applications, ranging from data services to imagery, voice, and video. Satellite uplinks and downlinks may experience various channel fades due to weather, blockages, terrestrial multipath, or jamming. A suite of mitigation techniques have been proposed to mitigate the wide range of channel impairments and optimize the use of available spectrum to deliver the highest possible data rate while satisfying quality of service (QoS) requirements. These techniques include channel interleaving and forward error correction (FEC) in the physical layer, dynamic coding and modulation (DCM) and automatic repeat request (ARQ) in the data link layer, prioritized packet forwarding in the network layer, and application codec adaptation (ACA) in the application layer. Since each mitigation strategy could potentially interact between layers, it is essential not only to assess the performance of each mitigation technique, but also to understand how multiple techniques work together. 12 This paper describes an emulation study of channel impairment mitigation using a combination of DCM, absolute priority scheduler (APS), and ACA. This is a continuation of our cross-layer mitigation studies previously published in [1,2]. Multiple video streams in different priorities were employed to demonstrate how underlying mitigation techniques work together to preserve the QoS of multiple applications under various channel fades. This paper presents the test bed architecture, mitigation techniques, test configurations, and test results.","PeriodicalId":378029,"journal":{"name":"2010 IEEE Aerospace Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130644230","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 : 2010-03-06DOI: 10.1109/AERO.2010.5446953
C. Edwards, K. Bruvold, J. Erickson, R. Gladden, J. Guinn, P. Ilott, B. Jai, M. Johnston, R. Kornfeld, T. Martin-Mur, G. W. Mcsmith, Reid Thomas, P. Varghese, G. Signori, P. Schmitz
The Phoenix Lander, first of NASA's Mars Scout missions, arrived at the Red Planet on May 25, 2008. From the moment the lander separated from its interplanetary cruise stage shortly before entry, the spacecraft could no longer communicate directly with Earth, and was instead entirely dependent on UHF relay communications via an international network of orbiting Mars spacecraft, including NASA's 2001 Mars Odyssey (ODY) and Mars Reconnaissance Orbiter (MRO) spacecraft, as well as ESA's Mars Express (MEX) spacecraft. All three orbiters captured critical event telemetry and/or tracking data during Phoenix entry, descent and landing. During the Phoenix surface mission, ODY and MRO provided command and telemetry services, far surpassing the original data return requirements. The availability of MEX as a backup relay asset enhanced the robustness of the overall relay plan. In addition to telecommunications services, Doppler tracking observables acquired on the UHF link yielded a highly accurate position for the Phoenix landing site.12
{"title":"Telecommunications relay support of the Mars Phoenix Lander mission","authors":"C. Edwards, K. Bruvold, J. Erickson, R. Gladden, J. Guinn, P. Ilott, B. Jai, M. Johnston, R. Kornfeld, T. Martin-Mur, G. W. Mcsmith, Reid Thomas, P. Varghese, G. Signori, P. Schmitz","doi":"10.1109/AERO.2010.5446953","DOIUrl":"https://doi.org/10.1109/AERO.2010.5446953","url":null,"abstract":"The Phoenix Lander, first of NASA's Mars Scout missions, arrived at the Red Planet on May 25, 2008. From the moment the lander separated from its interplanetary cruise stage shortly before entry, the spacecraft could no longer communicate directly with Earth, and was instead entirely dependent on UHF relay communications via an international network of orbiting Mars spacecraft, including NASA's 2001 Mars Odyssey (ODY) and Mars Reconnaissance Orbiter (MRO) spacecraft, as well as ESA's Mars Express (MEX) spacecraft. All three orbiters captured critical event telemetry and/or tracking data during Phoenix entry, descent and landing. During the Phoenix surface mission, ODY and MRO provided command and telemetry services, far surpassing the original data return requirements. The availability of MEX as a backup relay asset enhanced the robustness of the overall relay plan. In addition to telecommunications services, Doppler tracking observables acquired on the UHF link yielded a highly accurate position for the Phoenix landing site.12","PeriodicalId":378029,"journal":{"name":"2010 IEEE Aerospace Conference","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130651530","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 : 2010-03-06DOI: 10.1109/AERO.2010.5446658
J. Samson, E. Grobelny, Sandra Driesse-Bunn, M. Clark, Susan Van Portfliet
Funded by the NASA New Millennium Program (NMP) Space Technology 8 (ST8) project since 2004, the Dependable Multiprocessor (DM) project is a major step toward NASA's and DoD's long-held desire to fly Commercial-Off-The-Shelf (COTS) technology in space to take advantage of the higher performance and lower cost of COTS-based onboard processing solutions. The development of DM technology represents a significant paradigm shift. For applications that only need to be radiation tolerant, DM technology allows the user to fly 10x – 100x the processing capability of designs implemented with radiation hardened technologies. As a software-based, platform and technology-independent technology, DM allows space missions to keep pace with COTS developments. As a result, the processing technologies used in space applications no longer need to be 2 – 3 generations behind state-of-the-art terrestrial processing technologies. The DM project conducted its TRL6 Technology Validation in 2008 and 2009. The preliminary DM TRL6 technology validation demonstration was conducted in September of 2008. The results of the preliminary TRL6 technology validation demonstration were described in a paper presented at the 2009 IEEE Aerospace Conference [5]. The final TRL6 results are provided in [1], [2], and [3]. This paper includes a brief overview of DM technology and a brief overview of the overall TRL6 effort, but focuses on the 2009 TRL6 effort. The 2009 effort includes system-level radiation testing and post-TRL6 technology enhancements. Post-TRL6 enhancements include an upgraded DM implementation with enhanced data integrity protection, coordinated checkpointing, repetitive transient fault detection, Open MPI, true open system HAM (High Availability Middleware), and an updated flight configuration which is not subject to the constraints of the original ST8 spacecraft. 1, 2, 3
{"title":"Post-TRL6 Dependable Multiprocessor technology developments","authors":"J. Samson, E. Grobelny, Sandra Driesse-Bunn, M. Clark, Susan Van Portfliet","doi":"10.1109/AERO.2010.5446658","DOIUrl":"https://doi.org/10.1109/AERO.2010.5446658","url":null,"abstract":"Funded by the NASA New Millennium Program (NMP) Space Technology 8 (ST8) project since 2004, the Dependable Multiprocessor (DM) project is a major step toward NASA's and DoD's long-held desire to fly Commercial-Off-The-Shelf (COTS) technology in space to take advantage of the higher performance and lower cost of COTS-based onboard processing solutions. The development of DM technology represents a significant paradigm shift. For applications that only need to be radiation tolerant, DM technology allows the user to fly 10x – 100x the processing capability of designs implemented with radiation hardened technologies. As a software-based, platform and technology-independent technology, DM allows space missions to keep pace with COTS developments. As a result, the processing technologies used in space applications no longer need to be 2 – 3 generations behind state-of-the-art terrestrial processing technologies. The DM project conducted its TRL6 Technology Validation in 2008 and 2009. The preliminary DM TRL6 technology validation demonstration was conducted in September of 2008. The results of the preliminary TRL6 technology validation demonstration were described in a paper presented at the 2009 IEEE Aerospace Conference [5]. The final TRL6 results are provided in [1], [2], and [3]. This paper includes a brief overview of DM technology and a brief overview of the overall TRL6 effort, but focuses on the 2009 TRL6 effort. The 2009 effort includes system-level radiation testing and post-TRL6 technology enhancements. Post-TRL6 enhancements include an upgraded DM implementation with enhanced data integrity protection, coordinated checkpointing, repetitive transient fault detection, Open MPI, true open system HAM (High Availability Middleware), and an updated flight configuration which is not subject to the constraints of the original ST8 spacecraft. 1, 2, 3","PeriodicalId":378029,"journal":{"name":"2010 IEEE Aerospace Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130776612","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 : 2010-03-06DOI: 10.1109/AERO.2010.5446893
D. Emmons, M. Lobbia, T. Radcliffe, R. Bitten
NASA's goal to provide a human presence in space while contributing to the knowledge of the science of Earth, other planets, the solar system, and the universe requires a diverse set of scientific and exploration missions.12 Successful development and execution of these portfolios depends upon a sustainable and affordable long-term strategy. To provide a basis for an adequate annual funding profile to fit within NASA's budget, an objective affordability assessment of a mission's technical baseline, associated risks, and cost and schedule is fundamental. For example, NASA's Science Mission Directorate lists close to 100 planned science missions for launch within a 20-year window in the Agency Mission Planning Manifest maintained by the NASA Office of Program Analysis and Evaluation. On the human space flight side, the NASA Exploration Systems Mission Directorate (ESMD) is in the process of trying to develop several multi-billion dollar systems (e.g. Orion capsule, Ares launch vehicle, etc.) in parallel to meet an initial operational capability within the next 10 years. While portfolios such as these might be defined such that the estimated life-cycle costs are covered by the expected budget, there are a variety of factors that might initiate a need to re-plan the portfolio, including budget cuts, new mission content, new Administration direction, different reserves strategies, and cost and schedule overruns. This can be seen in the 2009 Review of U.S. Human Space Flight (HSF) Plans Committee initiated by the White House, which examined the ongoing U.S. human space flight plans and programs, as well as alternatives to the current program of record. Using an affordability analysis process developed by The Aerospace Corporation, assessments were performed using the Sand Chart Tool (SCT) to support these portfolio analyses. SCT was developed to provide insight into the behavior of large portfolios and strategic issues associated with re-plans and execution of the specified content. It can run in two modes: Planning Mode, which applies a temporal stretch algorithm to fit portfolio costs to the budget (by stretching out schedule as necessary), and Evaluation Mode, which performs a probabilistic Monte Carlo analysis to determine the robustness of a given plan after considering cost-growth risks, schedule linkages, and other factors. This paper will 1) look at why affordability analysis is important in managing complex/high-value Agency portfolios, 2) provide a general overview of SCT and the affordability analysis process, and 3) examine recent examples of affordability assessments performed on the ESMD portfolio in support of the Review of HSF Committee.
{"title":"Affordability assessments to support strategic planning and decisions at NASA","authors":"D. Emmons, M. Lobbia, T. Radcliffe, R. Bitten","doi":"10.1109/AERO.2010.5446893","DOIUrl":"https://doi.org/10.1109/AERO.2010.5446893","url":null,"abstract":"NASA's goal to provide a human presence in space while contributing to the knowledge of the science of Earth, other planets, the solar system, and the universe requires a diverse set of scientific and exploration missions.12 Successful development and execution of these portfolios depends upon a sustainable and affordable long-term strategy. To provide a basis for an adequate annual funding profile to fit within NASA's budget, an objective affordability assessment of a mission's technical baseline, associated risks, and cost and schedule is fundamental. For example, NASA's Science Mission Directorate lists close to 100 planned science missions for launch within a 20-year window in the Agency Mission Planning Manifest maintained by the NASA Office of Program Analysis and Evaluation. On the human space flight side, the NASA Exploration Systems Mission Directorate (ESMD) is in the process of trying to develop several multi-billion dollar systems (e.g. Orion capsule, Ares launch vehicle, etc.) in parallel to meet an initial operational capability within the next 10 years. While portfolios such as these might be defined such that the estimated life-cycle costs are covered by the expected budget, there are a variety of factors that might initiate a need to re-plan the portfolio, including budget cuts, new mission content, new Administration direction, different reserves strategies, and cost and schedule overruns. This can be seen in the 2009 Review of U.S. Human Space Flight (HSF) Plans Committee initiated by the White House, which examined the ongoing U.S. human space flight plans and programs, as well as alternatives to the current program of record. Using an affordability analysis process developed by The Aerospace Corporation, assessments were performed using the Sand Chart Tool (SCT) to support these portfolio analyses. SCT was developed to provide insight into the behavior of large portfolios and strategic issues associated with re-plans and execution of the specified content. It can run in two modes: Planning Mode, which applies a temporal stretch algorithm to fit portfolio costs to the budget (by stretching out schedule as necessary), and Evaluation Mode, which performs a probabilistic Monte Carlo analysis to determine the robustness of a given plan after considering cost-growth risks, schedule linkages, and other factors. This paper will 1) look at why affordability analysis is important in managing complex/high-value Agency portfolios, 2) provide a general overview of SCT and the affordability analysis process, and 3) examine recent examples of affordability assessments performed on the ESMD portfolio in support of the Review of HSF Committee.","PeriodicalId":378029,"journal":{"name":"2010 IEEE Aerospace Conference","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132459412","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 : 2010-03-06DOI: 10.1109/AERO.2010.5446678
U. Orguner, Per Skoglar, D. Tornqvist, F. Gustafsson
This paper presents a combined Point Mass Filter (PMF) and Particle Filter (PF), which utilizes the support of the PMF and the high particle density in the PF close to the current estimate. The result is a filter robust to unexpected process events but still with low error covariance. This filter is especially useful for target tracking applications, where target maneuvers suddenly can change unpredictably.
{"title":"Combined point-mass and particle filter for target tracking","authors":"U. Orguner, Per Skoglar, D. Tornqvist, F. Gustafsson","doi":"10.1109/AERO.2010.5446678","DOIUrl":"https://doi.org/10.1109/AERO.2010.5446678","url":null,"abstract":"This paper presents a combined Point Mass Filter (PMF) and Particle Filter (PF), which utilizes the support of the PMF and the high particle density in the PF close to the current estimate. The result is a filter robust to unexpected process events but still with low error covariance. This filter is especially useful for target tracking applications, where target maneuvers suddenly can change unpredictably.","PeriodicalId":378029,"journal":{"name":"2010 IEEE Aerospace Conference","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132518955","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 : 2010-03-06DOI: 10.1109/AERO.2010.5446908
C. Haskins, W. Millard
Demanding mass and power requirements across many low-cost NASA mission sets (Discovery, New Frontiers, Mars Scout, SMEX, MIDEX, and others) place a premium on lightweight, efficient, and versatile radios.1,2 A low power, low mass, modular, multi-band software-defined radio (SDR) has been developed by JHU/APL, under the name Frontier Radio, for use in communications, navigation, radio science, and sensor applications for a variety of NASA missions. The current SDR implementation features communications and Doppler navigation modes, and provides a highly capable platform to build upon for future technology enhancements. Features such as in-band channel assignment, bit rate, modulation format, turnaround ratio, loop bandwidths, and coding formats are reconfigurable in flight. Modularity within the core hardware and firmware platforms enable infusion of new technology with minimal non-recurring engineering (NRE) costs. Current configurations operate within the NASA S, X (under development), and Ka-bands (26 and 32 GHz), though alternate RF slices may be added and/or substituted for other bands or sensor applications. This SDR is currently capable of transmit data rates up to 25 Mbps (and higher with 8/16 PSK/QAM) and receive data rates up to 1.3 Mbps via QPSK, with significantly higher capability under development. Compatibility with NASA's STRS architecture helps promote the use of this SDR throughout the NASA community. Along with its low power (5 W receive mode w/internal ovenized oscillator and 28V bus power) and low mass (1.8/2.1 kg, single/dual band configuration), this SDR offers missions a combination of capabilities and efficiency. The NASA Radiation Belt Storm Probes (RBSP) mission is currently developing a flight implementation of this SDR (S-Band only), with launch planned for the year 2012.
许多低成本NASA任务(Discovery, New Frontiers, Mars Scout, SMEX, MIDEX等)对质量和功率的要求很高，因此需要轻量级、高效和多用途的无线电。JHU/APL开发了一种低功率、低质量、模块化、多波段软件定义无线电(SDR)，名为“前沿无线电”，用于NASA各种任务的通信、导航、无线电科学和传感器应用。目前的SDR实现具有通信和多普勒导航模式，并为未来的技术增强提供了一个强大的平台。诸如带内信道分配、比特率、调制格式、周转率、环路带宽和编码格式等特性都可以在飞行中重新配置。核心硬件和固件平台的模块化能够以最小的非重复工程(NRE)成本注入新技术。目前的配置在NASA S, X(正在开发中)和ka频段(26和32 GHz)内运行，尽管可以添加和/或替代其他频段或传感器应用。该SDR目前能够传输高达25 Mbps的数据速率(通过8/16 PSK/QAM可以更高)，并通过QPSK接收高达1.3 Mbps的数据速率，并且正在开发更高的能力。与NASA的STRS架构的兼容性有助于促进该SDR在整个NASA社区的使用。凭借其低功耗(5w接收模式W /内部烤箱振荡器和28V总线电源)和低质量(1.8/2.1 kg，单/双频配置)，该SDR为任务提供了功能和效率的结合。美国宇航局辐射带风暴探测器(RBSP)任务目前正在开发一种SDR(仅限s波段)的飞行实现，计划于2012年发射。
{"title":"Multi-band software defined radio for spaceborne communications, navigation, radio science, and sensors","authors":"C. Haskins, W. Millard","doi":"10.1109/AERO.2010.5446908","DOIUrl":"https://doi.org/10.1109/AERO.2010.5446908","url":null,"abstract":"Demanding mass and power requirements across many low-cost NASA mission sets (Discovery, New Frontiers, Mars Scout, SMEX, MIDEX, and others) place a premium on lightweight, efficient, and versatile radios.1,2 A low power, low mass, modular, multi-band software-defined radio (SDR) has been developed by JHU/APL, under the name Frontier Radio, for use in communications, navigation, radio science, and sensor applications for a variety of NASA missions. The current SDR implementation features communications and Doppler navigation modes, and provides a highly capable platform to build upon for future technology enhancements. Features such as in-band channel assignment, bit rate, modulation format, turnaround ratio, loop bandwidths, and coding formats are reconfigurable in flight. Modularity within the core hardware and firmware platforms enable infusion of new technology with minimal non-recurring engineering (NRE) costs. Current configurations operate within the NASA S, X (under development), and Ka-bands (26 and 32 GHz), though alternate RF slices may be added and/or substituted for other bands or sensor applications. This SDR is currently capable of transmit data rates up to 25 Mbps (and higher with 8/16 PSK/QAM) and receive data rates up to 1.3 Mbps via QPSK, with significantly higher capability under development. Compatibility with NASA's STRS architecture helps promote the use of this SDR throughout the NASA community. Along with its low power (5 W receive mode w/internal ovenized oscillator and 28V bus power) and low mass (1.8/2.1 kg, single/dual band configuration), this SDR offers missions a combination of capabilities and efficiency. The NASA Radiation Belt Storm Probes (RBSP) mission is currently developing a flight implementation of this SDR (S-Band only), with launch planned for the year 2012.","PeriodicalId":378029,"journal":{"name":"2010 IEEE Aerospace Conference","volume":"16 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133012762","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 : 2010-03-06DOI: 10.1109/AERO.2010.5446984
Melissa A. Jones, J. Elliott, L. Alkalai
The concept of the Lunette geophysical network of landers was conceived from a mission concept study to develop small, low cost landers applicable to a variety of lunar exploration activities including site selection and certification for future human lunar outposts. The original design was intended to launch six landers on an EELV (Evolved Expendable Launch Vehicle) as a secondary payload using the EELV Secondary Payload Adapter (ESPA) ring. A follow-on study of the same Lunette mission concept considered individual landers each having a dedicated solid rocket motor allowing for global-scale distribution for the establishment of geophysical network nodes for global network science. The payload for the geophysical network of landers was selected to be responsive to the science objectives outlined in the Scientific Context for Exploration of the Moon report [1] and the International Lunar Network (ILN) Final Report [2] would have the capability to take critical data continuously during the lunar night without requiring radioisotope power systems. This paper will discuss the systems engineering approach and design trades that allow for the current geophysical network lander concept to emerge from the original ESPA-based concept. 1 2
{"title":"Systems engineering approach and design trades for the Lunette geophysical network lander","authors":"Melissa A. Jones, J. Elliott, L. Alkalai","doi":"10.1109/AERO.2010.5446984","DOIUrl":"https://doi.org/10.1109/AERO.2010.5446984","url":null,"abstract":"The concept of the Lunette geophysical network of landers was conceived from a mission concept study to develop small, low cost landers applicable to a variety of lunar exploration activities including site selection and certification for future human lunar outposts. The original design was intended to launch six landers on an EELV (Evolved Expendable Launch Vehicle) as a secondary payload using the EELV Secondary Payload Adapter (ESPA) ring. A follow-on study of the same Lunette mission concept considered individual landers each having a dedicated solid rocket motor allowing for global-scale distribution for the establishment of geophysical network nodes for global network science. The payload for the geophysical network of landers was selected to be responsive to the science objectives outlined in the Scientific Context for Exploration of the Moon report [1] and the International Lunar Network (ILN) Final Report [2] would have the capability to take critical data continuously during the lunar night without requiring radioisotope power systems. This paper will discuss the systems engineering approach and design trades that allow for the current geophysical network lander concept to emerge from the original ESPA-based concept. 1 2","PeriodicalId":378029,"journal":{"name":"2010 IEEE Aerospace Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130910430","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 : 2010-03-06DOI: 10.1109/AERO.2010.5446728
Akil J. Middleton, S. Paschall, B. Cohanim
The goal of this paper is to describe a first-order performance analysis of a lunar hopper 1,2. A hopper is a vehicle that has both landing and surface mobility capabilities on a single platform. Unlike rovers, which traverse the lunar surface while in contact with the ground, hopping reuses the landing propulsion system to lift back off again and “hop” over the lunar terrain. Hopping, as a form of surface mobility, is a novel concept. As such, analysis must be performed to assess how it would fit with an overall lunar landing system architecture. Two trajectory categories are investigated to perform this assessment: the ballistic hop, where the vehicle launches itself into a ballistic trajectory toward the destination, and the hover hop, in which the vehicle ascends and maintains a constant altitude as it travels toward its desired location. Initially, parametric studies of the ballistic and hover hop are carried out in order to make observations about the performance of each hop. Using this data, it is possible to investigate the fuel-optimal hop trajectory. The delta-V costs for the ballistic and hover hops are compared for hop distances between 500 meters and 5000 meters, and in this range it is found that the ballistic hop and hover traverse have comparable delta-V costs. For the entire hop maneuver, however, the hover hop will always be the more delta-V expensive option due to the ascent and descent phases. Nevertheless, this does not rule out the hover hop as a feasible option due to its operational advantages over the ballistic hop.
{"title":"Small lunar lander/hopper performance analysis","authors":"Akil J. Middleton, S. Paschall, B. Cohanim","doi":"10.1109/AERO.2010.5446728","DOIUrl":"https://doi.org/10.1109/AERO.2010.5446728","url":null,"abstract":"The goal of this paper is to describe a first-order performance analysis of a lunar hopper 1,2. A hopper is a vehicle that has both landing and surface mobility capabilities on a single platform. Unlike rovers, which traverse the lunar surface while in contact with the ground, hopping reuses the landing propulsion system to lift back off again and “hop” over the lunar terrain. Hopping, as a form of surface mobility, is a novel concept. As such, analysis must be performed to assess how it would fit with an overall lunar landing system architecture. Two trajectory categories are investigated to perform this assessment: the ballistic hop, where the vehicle launches itself into a ballistic trajectory toward the destination, and the hover hop, in which the vehicle ascends and maintains a constant altitude as it travels toward its desired location. Initially, parametric studies of the ballistic and hover hop are carried out in order to make observations about the performance of each hop. Using this data, it is possible to investigate the fuel-optimal hop trajectory. The delta-V costs for the ballistic and hover hops are compared for hop distances between 500 meters and 5000 meters, and in this range it is found that the ballistic hop and hover traverse have comparable delta-V costs. For the entire hop maneuver, however, the hover hop will always be the more delta-V expensive option due to the ascent and descent phases. Nevertheless, this does not rule out the hover hop as a feasible option due to its operational advantages over the ballistic hop.","PeriodicalId":378029,"journal":{"name":"2010 IEEE Aerospace Conference","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130983208","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 : 2010-03-06DOI: 10.1109/AERO.2010.5446830
M. Z. Osmanbhoy, S. Runo, P. Mallasch
This paper describes how real-time faults can be automatically detected in Boeing 737 airplanes without significant hardware or software modifications, or potentially expensive system re-certification by employing a novel approach to Airplane Conditioning and Monitoring System (ACMS) usage.1 2
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Pub Date : 2010-03-06DOI: 10.1109/AERO.2010.5446712
Casey J. Pellizzari, Jason D. Schmidt
Phase unwrapping in the presence of branch points using a least mean square error (LMSE) wave-front reconstructor requires the use of a Postprocessing Congruence Operation (PCO) to ensure the unwrapped output is congruent or modulo-2π-equivalent to the wrapped input. 2π discontinuities known as branch cuts in the unwrapped phase are altered by the addition of a constant parameter h to the rotational component when applying the PCO. Selecting a value of h which minimizes the proportion of irradiance in the pupil-plane adjacent to branch cuts is an effective method to maximize performance of adaptive optics (AO) systems in strong turbulence. The optimal value of h varies significantly in open-loop AO or while the loop is closing. Once the loop is closed, optimal values tend to occur near h = 0. This paper proposes two algorithms which utilize this behavior to optimize the PCO and compares them with other unwrappers in closed-loop AO simulations. When compared to other PCO unwrappers, both algorithms reduced the probability of low Strehl ratios, as well as the normalized variance of the Strehl ratio. The second algorithm reduced normalized variance by up to 33 percent. AO systems which depend on steady performance and Strehl ratio values above a minimum threshold serve to benefit from these algorithms when operating in the presence of branch points.
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