Pub Date : 2020-03-01DOI: 10.1109/AERO47225.2020.9172515
P. McGarey, Tien Nguyen, T. Pailevanian, Issa Nensas
Moon Diver is a proposed mission to land and deploy an extreme-terrain, tethered rover for the exploration of Tran-quillitatis Pit, a large vertical cave entrance into the subsurface of Earth's Moon. By leveraging a supportive tether, the Axel rover, developed by NASA's Jet Propulsion Laboratory, would perform a controlled descent into the pit and deploy instruments along the pit wall. The purpose of this mission concept is to study a volcanic secondary crust as a function of depth in order to determine formation processes and chemical makeup. The lifeline of the mission would be the tether, which provides power from, and communication to the top-side lander. Critically, the tether also serves as mechanical support between the suspended rover and the lander, which acts as an anchor. While space tethers have been deployed both in orbit and terrestrially, the use of the proposed tether is unlike any known in the literature; the tether must come into contact with the terrain while under load. With respect to the environment, the tether must also survive abrasion from glassy regolith and volcanic rocks, bending around sharp edges, thermal extremes, and exposure to full spectrum ultra-violet (UV) radiation, all while reliably transferring up to 100 W of power and 1 Mbps of data. Furthermore, since the Axel rover pays out tether from an internal spool, the tether's diameter must be minimized to increase spool capacity, allowing for up to a 300-m traverse while also meeting static and dynamic strength requirements. This paper covers several phases of the tether's initial development, including i) a trade study of structure and materials with consideration for space heritage, ii) selected design justification, and iii) results from tests on prototype tethers looking into mechanical, electrical, and environmental properties, including exposure to rock-regolith abrasion, load profiles at temperature, and degradation due to UV exposure while exposed to vacuum. Finally, we provide insights and lessons learned from lab and field tests, which inform our continued effort to design a tether capable of surviving rugged, lunar conditions.
{"title":"Design and Test of an Electromechanical Rover Tether for the Exploration of Vertical Lunar Pits","authors":"P. McGarey, Tien Nguyen, T. Pailevanian, Issa Nensas","doi":"10.1109/AERO47225.2020.9172515","DOIUrl":"https://doi.org/10.1109/AERO47225.2020.9172515","url":null,"abstract":"Moon Diver is a proposed mission to land and deploy an extreme-terrain, tethered rover for the exploration of Tran-quillitatis Pit, a large vertical cave entrance into the subsurface of Earth's Moon. By leveraging a supportive tether, the Axel rover, developed by NASA's Jet Propulsion Laboratory, would perform a controlled descent into the pit and deploy instruments along the pit wall. The purpose of this mission concept is to study a volcanic secondary crust as a function of depth in order to determine formation processes and chemical makeup. The lifeline of the mission would be the tether, which provides power from, and communication to the top-side lander. Critically, the tether also serves as mechanical support between the suspended rover and the lander, which acts as an anchor. While space tethers have been deployed both in orbit and terrestrially, the use of the proposed tether is unlike any known in the literature; the tether must come into contact with the terrain while under load. With respect to the environment, the tether must also survive abrasion from glassy regolith and volcanic rocks, bending around sharp edges, thermal extremes, and exposure to full spectrum ultra-violet (UV) radiation, all while reliably transferring up to 100 W of power and 1 Mbps of data. Furthermore, since the Axel rover pays out tether from an internal spool, the tether's diameter must be minimized to increase spool capacity, allowing for up to a 300-m traverse while also meeting static and dynamic strength requirements. This paper covers several phases of the tether's initial development, including i) a trade study of structure and materials with consideration for space heritage, ii) selected design justification, and iii) results from tests on prototype tethers looking into mechanical, electrical, and environmental properties, including exposure to rock-regolith abrasion, load profiles at temperature, and degradation due to UV exposure while exposed to vacuum. Finally, we provide insights and lessons learned from lab and field tests, which inform our continued effort to design a tether capable of surviving rugged, lunar conditions.","PeriodicalId":114560,"journal":{"name":"2020 IEEE Aerospace Conference","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134210939","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 : 2020-03-01DOI: 10.1109/AERO47225.2020.9172331
E. Serabyn, T. Kim, K. Liewer, C. Lindensmith, K. Wallace, N. Oborny, M. Bedrossian, S. Rider, J. Nadeau
A promising way to search for microbial life in our solar system's Ocean Worlds is to make use of 3-d microscopes, as these can provide single-image inventories of the complete contents of liquid sample volumes. Two applicable 3d microscopy techniques are digital holographic microscopy and light-field fluorescence microscopy. The former can provide high-resolution imaging information on cellular morphology, structure, index of refraction, and motility, while the latter can identify and locate targeted molecule families, such as lipids and nucleic acids. The combination of this pair of 3-d techniques thus provides a powerful suite of diagnostic tools. We have recently combined both types of microscope into an integrated dual-mode microscope prototype aimed at demonstrating its utility at terrestrial field sites, and the combined instrument has already been taken on an initial foray into the field to assess its performance and shortcomings. Here we describe the design and capabilities of our dual-mode microscope, as well as initial performance measurements obtained during its first field trip to the local seashore.
{"title":"Demonstration of a dual-mode digital-holographic/light-field-fluorescence microscope for extant life searches","authors":"E. Serabyn, T. Kim, K. Liewer, C. Lindensmith, K. Wallace, N. Oborny, M. Bedrossian, S. Rider, J. Nadeau","doi":"10.1109/AERO47225.2020.9172331","DOIUrl":"https://doi.org/10.1109/AERO47225.2020.9172331","url":null,"abstract":"A promising way to search for microbial life in our solar system's Ocean Worlds is to make use of 3-d microscopes, as these can provide single-image inventories of the complete contents of liquid sample volumes. Two applicable 3d microscopy techniques are digital holographic microscopy and light-field fluorescence microscopy. The former can provide high-resolution imaging information on cellular morphology, structure, index of refraction, and motility, while the latter can identify and locate targeted molecule families, such as lipids and nucleic acids. The combination of this pair of 3-d techniques thus provides a powerful suite of diagnostic tools. We have recently combined both types of microscope into an integrated dual-mode microscope prototype aimed at demonstrating its utility at terrestrial field sites, and the combined instrument has already been taken on an initial foray into the field to assess its performance and shortcomings. Here we describe the design and capabilities of our dual-mode microscope, as well as initial performance measurements obtained during its first field trip to the local seashore.","PeriodicalId":114560,"journal":{"name":"2020 IEEE Aerospace Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132850593","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 : 2020-03-01DOI: 10.1109/AERO47225.2020.9172251
M. Werth, Jacob Lucas, Trent Kyono, Ian McQuaid, Justin Fletcher
Images of space objects may have their interpretability assessed with a Space-object National Imagery Interpretability Rating Scale (SNIIRS) score. The rules for such scores are specific, but the process of rating a large number of images can be time-consuming even for a skilled analyst. As this scale is subjective and based on interpretability of resolved features, it is also difficult to provide automated SNIIRS assessments with a simple algorithmic procedure. A Convolutional Neural Network (CNN) may be able to solve this problem, but such an effort requires a large labeled dataset of images. In this paper we will describe the effort to use wave-optics simulations to generate a dataset of SNIIRS-scored images of Low Earth Orbit (LEO) satellites observed from a ground-based optical observatory with varied turbulence conditions. This first iteration of the Scored Images of LEO Objects (SILO) dataset is intended to serve as a foundation for deep learning efforts, similar to how MNIST and ImageNet have been foundational datasets in other machine vision domains. This dataset is already being used in numerous machine learning efforts, including those pertaining to using CNNs to perform image interpretability assessment and to produce higher-resolution image recoveries from degraded image sets. In this paper we also describe some of the other potential uses for this dataset.
{"title":"SILO: A Machine Learning Dataset of Synthetic Ground-Based Observations of LEO Satellites","authors":"M. Werth, Jacob Lucas, Trent Kyono, Ian McQuaid, Justin Fletcher","doi":"10.1109/AERO47225.2020.9172251","DOIUrl":"https://doi.org/10.1109/AERO47225.2020.9172251","url":null,"abstract":"Images of space objects may have their interpretability assessed with a Space-object National Imagery Interpretability Rating Scale (SNIIRS) score. The rules for such scores are specific, but the process of rating a large number of images can be time-consuming even for a skilled analyst. As this scale is subjective and based on interpretability of resolved features, it is also difficult to provide automated SNIIRS assessments with a simple algorithmic procedure. A Convolutional Neural Network (CNN) may be able to solve this problem, but such an effort requires a large labeled dataset of images. In this paper we will describe the effort to use wave-optics simulations to generate a dataset of SNIIRS-scored images of Low Earth Orbit (LEO) satellites observed from a ground-based optical observatory with varied turbulence conditions. This first iteration of the Scored Images of LEO Objects (SILO) dataset is intended to serve as a foundation for deep learning efforts, similar to how MNIST and ImageNet have been foundational datasets in other machine vision domains. This dataset is already being used in numerous machine learning efforts, including those pertaining to using CNNs to perform image interpretability assessment and to produce higher-resolution image recoveries from degraded image sets. In this paper we also describe some of the other potential uses for this dataset.","PeriodicalId":114560,"journal":{"name":"2020 IEEE Aerospace Conference","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132925658","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 : 2020-03-01DOI: 10.1109/AERO47225.2020.9172541
S. Ono, Shohei Namikawa, Kazuya Yoshida
A planetary rover experiences mobility problems, such as excessive slippage and entrapment, on loose terrain known as regolith. To prevent such situations, understanding wheel-soil interaction mechanics is necessary. Thus, this study focuses on the soil deformation beneath a grouser wheel and the wheel traction performance. The soil deformation is analyzed by using particle image velocimetry (PIV) technique, and the wheel traction is measured by a force-torque (FT) sensor. The experimental results present that the soil around a grouser moves to the directions on the front and rear of the wheel when the grouser enters into the soil. After that, the soil flow describes an arc-shaped flow from the front of the wheel towards the rear-end of the wheel caused by the grouser. These results indicate that the grouser wheel causes a different flow of soil than a wheel without grousers. Therefore, a model for the grouser wheel that takes into account the soil deformation must be developed in the future. We also investigate the effects of the normal load of the wheel on the soil deformation. The normal load of the wheel affects the thickness of the soil deformation area rather than the shape of the boundary line of the soil deformation area. In addition, the maximum thickness of the soil deformation area and the velocity of the soil particles increase with an increase of the normal load of the wheel. As for the wheel performance, the increase of the normal load causes an increase of wheel sinkage and traveling traction. From these results, it can be deduced that an increase in the thickness of the soil deformation area leads to an increase in the traction performance of the grouser wheel. In conclusion, this work contributes further to the understanding of wheel-soil interaction and the relationship between wheel performance and soil deformation.
{"title":"Analysis of Soil Deformation and Wheel Traction on Loose Terrain Using PIV","authors":"S. Ono, Shohei Namikawa, Kazuya Yoshida","doi":"10.1109/AERO47225.2020.9172541","DOIUrl":"https://doi.org/10.1109/AERO47225.2020.9172541","url":null,"abstract":"A planetary rover experiences mobility problems, such as excessive slippage and entrapment, on loose terrain known as regolith. To prevent such situations, understanding wheel-soil interaction mechanics is necessary. Thus, this study focuses on the soil deformation beneath a grouser wheel and the wheel traction performance. The soil deformation is analyzed by using particle image velocimetry (PIV) technique, and the wheel traction is measured by a force-torque (FT) sensor. The experimental results present that the soil around a grouser moves to the directions on the front and rear of the wheel when the grouser enters into the soil. After that, the soil flow describes an arc-shaped flow from the front of the wheel towards the rear-end of the wheel caused by the grouser. These results indicate that the grouser wheel causes a different flow of soil than a wheel without grousers. Therefore, a model for the grouser wheel that takes into account the soil deformation must be developed in the future. We also investigate the effects of the normal load of the wheel on the soil deformation. The normal load of the wheel affects the thickness of the soil deformation area rather than the shape of the boundary line of the soil deformation area. In addition, the maximum thickness of the soil deformation area and the velocity of the soil particles increase with an increase of the normal load of the wheel. As for the wheel performance, the increase of the normal load causes an increase of wheel sinkage and traveling traction. From these results, it can be deduced that an increase in the thickness of the soil deformation area leads to an increase in the traction performance of the grouser wheel. In conclusion, this work contributes further to the understanding of wheel-soil interaction and the relationship between wheel performance and soil deformation.","PeriodicalId":114560,"journal":{"name":"2020 IEEE Aerospace Conference","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133627129","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 : 2020-03-01DOI: 10.1109/AERO47225.2020.9172261
Lynn von Kurnatowski, M. Stoffers, M. Weigel, Michael Meinel, Yi Wasser, K. Rack, H. Fiedler
For Space Situational Awareness, the German Aerospace Center (DLR) develops the software system “Back-bone Catalogue of Relational Debris Information” (BACARDI), which allows for keeping track of resident space objects. BACARDI's key features are automated processing services which produce orbit information and products like collision warnings. We present how we applied new methods of software analytics to the BACARDI project. BACARDI is an example of a complex software system with large development effort carried out by a team of various specialists. Our goal is to design and implement an efficient software development process, balancing the explorative character of a research project and operational requirements (i.e. tailored from official standards in the aerospace domain). Therefore, we established a software development process for the project where we focus on software quality. We applied methods to structure, communicate, and utilize the diverse skills, knowledge, and experience in the team concisely and precisely. After one year of practical utilization, we analyzed the process based on the repository data. By analyzing these data, we assess and prove the effects of the introduced process on the development of a software, which is used in the aerospace domain.
{"title":"Scientific Software Engineering: Mining Repositories to gain insights into BACARDI","authors":"Lynn von Kurnatowski, M. Stoffers, M. Weigel, Michael Meinel, Yi Wasser, K. Rack, H. Fiedler","doi":"10.1109/AERO47225.2020.9172261","DOIUrl":"https://doi.org/10.1109/AERO47225.2020.9172261","url":null,"abstract":"For Space Situational Awareness, the German Aerospace Center (DLR) develops the software system “Back-bone Catalogue of Relational Debris Information” (BACARDI), which allows for keeping track of resident space objects. BACARDI's key features are automated processing services which produce orbit information and products like collision warnings. We present how we applied new methods of software analytics to the BACARDI project. BACARDI is an example of a complex software system with large development effort carried out by a team of various specialists. Our goal is to design and implement an efficient software development process, balancing the explorative character of a research project and operational requirements (i.e. tailored from official standards in the aerospace domain). Therefore, we established a software development process for the project where we focus on software quality. We applied methods to structure, communicate, and utilize the diverse skills, knowledge, and experience in the team concisely and precisely. After one year of practical utilization, we analyzed the process based on the repository data. By analyzing these data, we assess and prove the effects of the introduced process on the development of a software, which is used in the aerospace domain.","PeriodicalId":114560,"journal":{"name":"2020 IEEE Aerospace Conference","volume":"38 12","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133686447","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 : 2020-03-01DOI: 10.1109/AERO47225.2020.9172690
D. Jennings, H. Pernicka
The work this paper describes identifies continuous natural relative trajectories near the collinear libration points numerically from the nonlinear CR3BP differential equations by utilizing a shooting method with a two-level differential corrector. The focus is on determining natural formations in the vicinity of the Earth-Moon $mathrm{L}_{2}$ point when using the nonlinear equations of motion of the CR3BP. Upon identifying these relative trajectories analysis is conducted to determine drift rates of the uncontrolled trajectories compared to linearized formations near the collinear libration points. In addition, stationkeeping techniques are applied to determine the required maneuvers and frequencies and to assess $triangle mathcal{V}$ maintenance of the nominal trajectories.
{"title":"Numerical Determination of Natural Spacecraft Formations Near the Collinear Libration Points","authors":"D. Jennings, H. Pernicka","doi":"10.1109/AERO47225.2020.9172690","DOIUrl":"https://doi.org/10.1109/AERO47225.2020.9172690","url":null,"abstract":"The work this paper describes identifies continuous natural relative trajectories near the collinear libration points numerically from the nonlinear CR3BP differential equations by utilizing a shooting method with a two-level differential corrector. The focus is on determining natural formations in the vicinity of the Earth-Moon $mathrm{L}_{2}$ point when using the nonlinear equations of motion of the CR3BP. Upon identifying these relative trajectories analysis is conducted to determine drift rates of the uncontrolled trajectories compared to linearized formations near the collinear libration points. In addition, stationkeeping techniques are applied to determine the required maneuvers and frequencies and to assess $triangle mathcal{V}$ maintenance of the nominal trajectories.","PeriodicalId":114560,"journal":{"name":"2020 IEEE Aerospace Conference","volume":"1100 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133667019","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 : 2020-03-01DOI: 10.1109/AERO47225.2020.9172694
Nils Pachler, J. Luis, Markus Guerster, E. Crawley, B. Cameron
In recent years, communications satellites' payloads have been evolving from static to highly flexible components. Modern satellites are able to provide four orders of magnitude higher throughput than their predecessors forty years ago, going from a few Mbps to several hundreds of Gbps. This enhancement in performance is aligned with an increasing highly-variable demand. In order to dynamically and efficiently manage the satellite's resources, an automatic tool is needed. This work presents an implementation of a new metaheuristic algorithm based on Particle Swarm Optimization (PSO) to solve the joint power and bandwidth allocation problem. We formulate this problem as a multi-objective approach that considers the different constraints of a communication satellite system. The evaluation function corresponds to a full-RF link budget model that accounts for adaptive coding and modulation techniques as well as multiple types of losses. We benchmark the algorithm using a realistic traffic model provided by a satellite communications operator and under time restrictions present in an operational environment. The results show a fast convergence of the PSO algorithm, reaching an admissible solution in seconds. However, the PSO tends to get stuck in local optima and often fails to reach the global optimum. This motivates the creation of a hybrid metaheuristic combining the presented PSO with a Genetic Algorithm (GA). We show that this approach dominates the PSO-only both in terms of power consumption and service rate. Furthermore, we also show that the hybrid implementation outperforms a GA-only algorithm for low run-time executions (10-second executions). The hybrid provides up to an 85% power reduction and up to 10% better service rate in this case.
{"title":"Allocating Power and Bandwidth in Multibeam Satellite Systems using Particle Swarm Optimization","authors":"Nils Pachler, J. Luis, Markus Guerster, E. Crawley, B. Cameron","doi":"10.1109/AERO47225.2020.9172694","DOIUrl":"https://doi.org/10.1109/AERO47225.2020.9172694","url":null,"abstract":"In recent years, communications satellites' payloads have been evolving from static to highly flexible components. Modern satellites are able to provide four orders of magnitude higher throughput than their predecessors forty years ago, going from a few Mbps to several hundreds of Gbps. This enhancement in performance is aligned with an increasing highly-variable demand. In order to dynamically and efficiently manage the satellite's resources, an automatic tool is needed. This work presents an implementation of a new metaheuristic algorithm based on Particle Swarm Optimization (PSO) to solve the joint power and bandwidth allocation problem. We formulate this problem as a multi-objective approach that considers the different constraints of a communication satellite system. The evaluation function corresponds to a full-RF link budget model that accounts for adaptive coding and modulation techniques as well as multiple types of losses. We benchmark the algorithm using a realistic traffic model provided by a satellite communications operator and under time restrictions present in an operational environment. The results show a fast convergence of the PSO algorithm, reaching an admissible solution in seconds. However, the PSO tends to get stuck in local optima and often fails to reach the global optimum. This motivates the creation of a hybrid metaheuristic combining the presented PSO with a Genetic Algorithm (GA). We show that this approach dominates the PSO-only both in terms of power consumption and service rate. Furthermore, we also show that the hybrid implementation outperforms a GA-only algorithm for low run-time executions (10-second executions). The hybrid provides up to an 85% power reduction and up to 10% better service rate in this case.","PeriodicalId":114560,"journal":{"name":"2020 IEEE Aerospace Conference","volume":"114 5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132566336","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 : 2020-03-01DOI: 10.1109/AERO47225.2020.9172360
Thomas B. Cook, Aidan Phillips, Christopher Siak, A. George, B. Grainger
Space experiments in low earth orbit (LEO) are becoming more ambitious and the power electronic systems for these missions are quickly becoming outdated when compared to the power-dense and highly efficient commercial solutions used to power modern processors. In this work, a comparison is presented between several radiation-hardened (rad-hard) and commercial-off-the-shelf (COTS) point-of-load (PoL) converters with a focus on Gallium Nitride (GaN) switching FETS. The converters were designed and evaluated based on their electrical and thermal performance when supplying power to computational loads in a LEO environment. This work is presented in the context of supplying power to a 1U FPGA-based computing platform that features a mix of COTS and rad-hard components, and a modular power system.
{"title":"Evaluation of Point of Load Converters for Space Computational Loads","authors":"Thomas B. Cook, Aidan Phillips, Christopher Siak, A. George, B. Grainger","doi":"10.1109/AERO47225.2020.9172360","DOIUrl":"https://doi.org/10.1109/AERO47225.2020.9172360","url":null,"abstract":"Space experiments in low earth orbit (LEO) are becoming more ambitious and the power electronic systems for these missions are quickly becoming outdated when compared to the power-dense and highly efficient commercial solutions used to power modern processors. In this work, a comparison is presented between several radiation-hardened (rad-hard) and commercial-off-the-shelf (COTS) point-of-load (PoL) converters with a focus on Gallium Nitride (GaN) switching FETS. The converters were designed and evaluated based on their electrical and thermal performance when supplying power to computational loads in a LEO environment. This work is presented in the context of supplying power to a 1U FPGA-based computing platform that features a mix of COTS and rad-hard components, and a modular power system.","PeriodicalId":114560,"journal":{"name":"2020 IEEE Aerospace Conference","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131689536","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 : 2020-03-01DOI: 10.1109/AERO47225.2020.9172309
Stefan R. Martin, P. Douglas Lisman, D. Webb, G. Kuan, H. Philip Stahl, J. Krist, K. Warfield
The National Academies' 2020 Decadal Survey on Astronomy and Astrophysics will provide a broad vision for future science in these disciplines and the Habitable Exoplanet Observatory (HabEx) is one of four major observatory missions extensively studied in preparation for the survey. HabEx is a space telescope with a 4 m diameter primary mirror, carrying a complement of two general astrophysics camera/spectrographs with coverage from the far UV to the near infrared as well as two key instruments for exoplanet science. These exoplanet instruments consist of a high performance coronagraph (that places stringent demands on the overall observatory design and performance) and a remote (tens of megameters distant) formation flying occulter, consisting of a 52 m diameter starshade deployed from a second launch vehicle. This paper discusses the specific features of the observatory that permit high contrast coronagraphy at the 10−10 contrast level and the design considerations for the coronagraph itself. The starshade design is discussed in the context of the current technology development activities being undertaken by NASA to bring starshade readiness up to TRL5.
{"title":"The HabEx Observatory: A Coronagraph and a Starshade for Exoplanet Science","authors":"Stefan R. Martin, P. Douglas Lisman, D. Webb, G. Kuan, H. Philip Stahl, J. Krist, K. Warfield","doi":"10.1109/AERO47225.2020.9172309","DOIUrl":"https://doi.org/10.1109/AERO47225.2020.9172309","url":null,"abstract":"The National Academies' 2020 Decadal Survey on Astronomy and Astrophysics will provide a broad vision for future science in these disciplines and the Habitable Exoplanet Observatory (HabEx) is one of four major observatory missions extensively studied in preparation for the survey. HabEx is a space telescope with a 4 m diameter primary mirror, carrying a complement of two general astrophysics camera/spectrographs with coverage from the far UV to the near infrared as well as two key instruments for exoplanet science. These exoplanet instruments consist of a high performance coronagraph (that places stringent demands on the overall observatory design and performance) and a remote (tens of megameters distant) formation flying occulter, consisting of a 52 m diameter starshade deployed from a second launch vehicle. This paper discusses the specific features of the observatory that permit high contrast coronagraphy at the 10−10 contrast level and the design considerations for the coronagraph itself. The starshade design is discussed in the context of the current technology development activities being undertaken by NASA to bring starshade readiness up to TRL5.","PeriodicalId":114560,"journal":{"name":"2020 IEEE Aerospace Conference","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131861715","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 : 2020-03-01DOI: 10.1109/AERO47225.2020.9172479
Darius Yaghoubi, A. Schnell
As part of a Mars Sample Return (MSR) campaign, two Mars Ascent Vehicle (MAV) configurations have been designed in parallel. Each ascent vehicle configuration has a different propulsion system which ultimately leads to two unique vehicle designs. As part of a Preliminary Architecture Assessment (PAA), these vehicle designs were developed to the same level of maturity in order to inform the selection of one of the vehicles as the point of departure design for the campaign. The selection will be made in November 2019. The initial MSR architecture called for a hybrid-based propulsion MAV. This type of propulsion system calls for a solid wax motor that would utilize liquid MON-25 as an oxidizer. Hybrid rocket propulsion allows for more flexibility than traditional solid or liquid propulsion options, and typically benefits from the advantages of both. A hybrid motor can be throttled and shut down easily, and avoids significant risk in manufacturing and handling. On a theoretical level, hybrid motors perform at a higher specific impulse (Isp) than solid motors. The primary disadvantage of hybrid motors comes from additional complexity and significantly less flight heritage and low Technology Readiness Level (TRL). This paper describes the design of the hybrid propulsion configuration. An additional paper will be published describing the design of the solid propulsion configuration1. The hybrid propulsion configuration MAV was developed in 2019 by NASA Marshall Space Flight Center (MSFC) in association with NASA Jet Propulsion Laboratory (JPL). It features a Single Stage to Orbit (SSTO) design with an SP7A solid wax fuel and MON-25 liquid oxidizer. The liquid portion of the vehicle allows for a Liquid Injection Thrust Vector Controller (LITVC) as well as hypergolic propellant additives for ignition. The vehicle was designed to deliver approximately 0.31kg of Martian geological samples to a circular orbit at Mars of 343km at a 25° inclination. Although hybrid propulsion in general has been used on launch vehicles in the past, the integrated vehicle subsystems that operate in conjunction with these propulsion elements do not typically operate in a Martian environment, which in this application can get as cold as −40°C. The PAA advanced the maturity of these subsystems by performing detailed design and analysis on the vehicle with respect to structures and mechanisms, Guidance/Navigation/Control (GNC) systems, avionics, Reaction Control System (RCS), LITVC, thermal environments, and advanced Computational Fluid Dynamics (CFD). This paper will summarize the results of these studies.
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