{"project":{"acronym":"","projectId":91536,"title":"Modeling Sub-500MHz Space-Borne Radar Signal Propagation in Complex Media","primaryTaxonomyNodes":[{"taxonomyNodeId":10822,"taxonomyRootId":8816,"parentNodeId":10818,"level":3,"code":"TX11.2.4","title":"Science Modeling","definition":"Science modeling uses mathematical models to quantify the physical processes as a function of underlying variables.","exampleTechnologies":"Fortran compatible and interoperable parallel libraries, high performance processor toolset for science modeling, quality metrics for science data, toolset for concurrent data diagnostics and acquisition for science modeling, software infrastructure for sensor webs, planetary contaminant modeling","hasChildren":false,"hasInteriorContent":true}],"startTrl":2,"currentTrl":3,"endTrl":3,"benefits":"The outcomes of this research are expected to markedly aid NASA/ESA mission-related trade and performance studies while stimulating development of comprehensive, robust low-frequency ionospheric mapping and environmental distortion mitigation techniques.","description":"Space-borne radar platforms are becoming increasingly prevalent in current and planned missions by NASA and partner organizations (e.g. the European Space Agency [ESA]) for a number of microwave remote sensing applications in the terrestrial and space domains. Examples of such missions include the Mars Express, Mars Reconnaissance Orbiter (MRO), BIOMASS, JUICE, Global Precipitation Measurement system, CloudSat, and Cassini. Depending upon the specific application, certain frequency ranges are typically deemed more optimal than others. In applications wherein the radar signal must achieve deep penetration through layers such as ice, vegetation, and top-soil, low-frequency radar systems (typically sub-500MHz) such as those of the MRO, Mars Express, JUICE, and BIOMASS are typically favored over higher-frequency alternatives like those used in CloudSat and Cassini due to lower signal loss associated with conductive ground layers. Despite this advantage of low-frequency signals, when using such signals to perform terrestrial and Martian remote sensing operations from space, the ionosphere will distort propagating electromagnetic (EM) fields, with these distortive effects exacerbating as the frequency reduces. Without adaptive, robust distortion prediction and mitigation techniques, the ionosphere will continue posing a barrier to current and future NASA/ESA remote sensing missions seeking to probe deep into ice, vegetation, and ground layers. Furthermore, despite the presence of external data sources such as the Global Positioning System to perform ionospheric mapping, it may be desired to map the ionosphere in real-time using the same low-frequency radar to capture instantaneous snapshots of the ionosphere’s properties during the radar’s flight path to provide more accurate information to bias mitigation algorithms. Therefore, the development of robust, low-frequency ionospheric mapping techniques represents an equally important and complementary pursuit to developing bias correction techniques. Similar issues will assume relevance when sounding extraterrestrial sub-surface environments containing media exhibiting exotic EM properties, potentially hindering the success of underground water and hydrocarbon detection without proper mitigation measures. However, these efforts all hinge upon accurate modeling of the environments EM characteristics to better understand the signal-environment interaction and its dependence upon the specific radar system used, which is the central theme of my proposed research. I will first extend and unify a number of isolated models concerning EM wave propagation in complex media into a comprehensive model that more accurately predicts the received EM fields at the radar platform. I will then implement this model in numerical EM codes to study how the ionosphere and complex sub-surface topologies can be expected to distort low-frequency EM waves propagating through these environments. Numerical results and conclusions on signal distortions incurred, as well as on the performance limits of current ionospheric mapping and sub-surface sounding techniques, as a function of center operating frequency, signal bandwidth, antenna geometry, and environmental topology, are expected to be the final outcomes of this research, which are expected to markedly aid NASA/ESA mission-related trade and performance studies while stimulating development of comprehensive, robust low-frequency ionospheric mapping and environmental distortion mitigation techniques.","startYear":2013,"startMonth":8,"endYear":2016,"endMonth":12,"statusDescription":"Completed","principalInvestigators":[{"contactId":151230,"canUserEdit":false,"firstName":"Fernando","lastName":"Teixeira","fullName":"Fernando Teixeira","fullNameInverted":"Teixeira, Fernando","publicEmail":false,"nacontact":false}],"programDirectors":[{"contactId":84634,"canUserEdit":false,"firstName":"Claudia","lastName":"Meyer","fullName":"Claudia M Meyer","fullNameInverted":"Meyer, Claudia M","middleInitial":"M","primaryEmail":"claudia.m.meyer@nasa.gov","publicEmail":true,"nacontact":false}],"programExecutives":[{"contactId":84634,"canUserEdit":false,"firstName":"Claudia","lastName":"Meyer","fullName":"Claudia M Meyer","fullNameInverted":"Meyer, Claudia M","middleInitial":"M","primaryEmail":"claudia.m.meyer@nasa.gov","publicEmail":true,"nacontact":false}],"programManagers":[{"contactId":183514,"canUserEdit":false,"firstName":"Hung","lastName":"Nguyen","fullName":"Hung D Nguyen","fullNameInverted":"Nguyen, Hung D","middleInitial":"D","primaryEmail":"hung.d.nguyen@nasa.gov","publicEmail":true,"nacontact":false}],"projectManagers":[{"contactId":28299,"canUserEdit":false,"firstName":"Anthony","lastName":"Freeman","fullName":"Anthony Freeman","fullNameInverted":"Freeman, Anthony","primaryEmail":"anthony.freeman@jpl.nasa.gov","publicEmail":true,"nacontact":false}],"coInvestigators":[{"contactId":258592,"canUserEdit":false,"firstName":"Kamalesh","lastName":"Sainath","fullName":"Kamalesh K Sainath","fullNameInverted":"Sainath, Kamalesh K","middleInitial":"K","primaryEmail":"144634@jpl.nasa.gov","publicEmail":true,"nacontact":false}],"website":"https://www.nasa.gov/directorates/spacetech/home/index.html","libraryItems":[],"transitions":[{"transitionId":75701,"projectId":91536,"transitionDate":"2016-12-01","path":"Closed Out","details":"Summary: Investigated electromagnetic (EM) wave propagation, in diverse layered geophysical media, using both analytical models and computational models. Conclusion 1: Judicious choices of complex-plane integration paths, in tandem with suitable coordinate rotations, formula re-castings, etc., indeed can allow for sensor and material-robust fast and accurate numerical modeling of EM sensors in diverse layered media. Conclusion 2: Incorporating effects of material anisotropy and layering are, especially for low- loss geophysical media, critical to better understanding why Interferometric Synthetic Aperture Radar [InSAR] data can rapidly decorrelate and exhibit data-invalidating phase biases even for interferometric baseline lengths well below the normally predicated maximum/”critical” baseline. Computational modeling: Develop algorithms that model EM wave propagation through layered geophysical media in a manner robust to sensor and environment characteristics. Previous algorithms typically fail to produce fast, accurate numerical EM field results for steeply deviated sensors, low radiation frequencies, and highly anisotropic geophysical media. Analytical modeling: Past models do not robustly capture how a SAR’s transmitted EM pulse propagates and scatters from layered anisotropic media, hence cannot predict phase biases and interferometric decorrelations that can occur even for very small InSAR baseline separations. Developed models address this need. ","infoText":"Closed out","infoTextExtra":"","dateText":"December 2016"}],"responsibleMd":{"acronym":"STMD","canUserEdit":false,"city":"","external":false,"linkCount":0,"organizationId":4875,"organizationName":"Space Technology Mission Directorate","organizationType":"NASA_Mission_Directorate","naorganization":false,"organizationTypePretty":"NASA Mission Directorate"},"program":{"acronym":"STRG","active":true,"description":"
\tThe Space Technology Research Grants Program will accelerate the development of "push" technologies to support the future space science and exploration needs of NASA, other government agencies and the commercial space sector. Innovative efforts with high risk and high payoff will be encouraged. The program is composed of two competitively awarded components.
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