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OUR INSTRUMENT CONSISTS OF THREE SUBSYSTEMS: 1) THE LOW NOISE FRONT END (LNFE)  DEVELOPED FROM THE SOOP-AD (IIP-13) AIRBORNE DEMONSTRATION INSTRUMENT AND REDESIGNED FOR A CUBESAT FORM FACTOR UNDER GSFC INTERNAL FUNDING; 2) THE DIGITAL BACK END (DBE)  A MODIFICATION OF THE CION INSTRUMENT FLYING ON CICERO THAT CAPITALIZES ON THE EXTENSIVE HERITAGE OF THE BLACKJACK AND TRIG GPS RECEIVERS; AND 3) AN ARRAY OF COTS ANTENNAS. LNFE HAS A PATENT-PENDING ARCHITECTURE THAT USES AN INTERNAL CALIBRATION NETWORK BASED UPON OUR EXPERIENCE WITH THE AQUARIUS AND SMAP MISSIONS. IT ALSO IS CAPABLE OF ANTENNA SWAPPING TO SUPPRESS THE EFFECTS OF ANTENNA PHASE AND GAIN IMBALANCES. RF CIRCUITS ARE SHIELDED FROM OUT OF BAND SIGNALS AND SPACECRAFT-GENERATED ELECTROMAGNETIC INTERFERENCE (EMI). DBE EMPLOYS A COMBINATION OF OFF-THE-SHELF HARDWARE WITH A CUSTOM-DESIGNED RF/CLK/HOST BOARD AND WILL BE MODIFIED TO ACCOMMODATE THE RAD-TOLERANT SPACE MICRO CUBESAT SPACE PROCESSOR (CSP) TO MAKE THE INSTRUMENT SUITABLE FOR A FUTURE NASA CLASS D MISSION. FOUR P-BAND DOWN-CONVERTERS AND A HIGH-PERFORMANCE SAMPLING CLOCK ARE USED TO ACQUIRE DATA IN TWO POLARIZATIONS FROM THE TWO ANTENNAS (ZENITH AND NADIR). SUCCESS WITH SNOOPI WILL RETIRE THE CRITICAL RISKS ASSOCIATED WITH A P-BAND SOOP SATELLITE MISSION  AND WE WILL EXIT WITH A TRL-7 INSTRUMENT. THIS INSTRUMENT WILL ENABLE DIRECT MEASUREMENTS OF RZSM AND SWE THAT ARE NOT PRESENTLY POSSIBLE AND WILL ALSO BE ORDERS OF MAGNITUDE LOWER IN SIZE WEIGHT AND POWER (SWAP) THAN COMPARABLE ACTIVE RADARS DUE TO THE RE-UTILIZATION OF POWERFUL ANTHROPOGENIC SIGNALS. COUPLED WITH THE USE OF SMALL  WIDE BEAM ANTENNAS  A P-BAND SOOP MISSION IS AN IDEAL CANDIDATE FOR A LARGE CONSTELLATION OF MICRO-SATELLITES OR HOSTED PAYLOADS. THIS CONSTELLATION COULD BE PROPOSED TO A FUTURE EARTH VENTURE/CONTINUITY OR EARTH SYSTEM EXPLORER PROGRAM.","funder_award_id":"80NSSC18K1524","funder_id":"https://openalex.org/F4320306101","funder_display_name":"National Aeronautics and Space Administration"},{"id":"https://openalex.org/G5952312098","display_name":null,"funder_award_id":"80HQTR18A0024","funder_id":"https://openalex.org/F4320306101","funder_display_name":"National Aeronautics and Space Administration"}],"funders":[{"id":"https://openalex.org/F4320306101","display_name":"National Aeronautics and Space Administration","ror":"https://ror.org/027ka1x80"}],"has_content":{"pdf":false,"grobid_xml":false},"content_urls":null,"referenced_works_count":25,"referenced_works":["https://openalex.org/W2020972932","https://openalex.org/W2027468514","https://openalex.org/W2040957337","https://openalex.org/W2041076557","https://openalex.org/W2044927495","https://openalex.org/W2075056964","https://openalex.org/W2081120066","https://openalex.org/W2106920307","https://openalex.org/W2109362828","https://openalex.org/W2118799063","https://openalex.org/W2128682602","https://openalex.org/W2542479991","https://openalex.org/W2590018691","https://openalex.org/W2612461531","https://openalex.org/W2763763040","https://openalex.org/W2772772654","https://openalex.org/W2787502967","https://openalex.org/W2905871199","https://openalex.org/W2952101268","https://openalex.org/W2972253584","https://openalex.org/W3011432147","https://openalex.org/W3091952031","https://openalex.org/W3156501644","https://openalex.org/W3205533591","https://openalex.org/W6676196961"],"related_works":["https://openalex.org/W2375155232","https://openalex.org/W2391759637","https://openalex.org/W3083266690","https://openalex.org/W3159078558","https://openalex.org/W1524396731","https://openalex.org/W3001875135","https://openalex.org/W2050586028","https://openalex.org/W3148032812","https://openalex.org/W2977254096","https://openalex.org/W2075206456"],"abstract_inverted_index":{"Land-reflected":[0],"signals":[1],"from":[2,39],"a":[3,19,50,56,65,71,109,154,170],"geosynchronous":[4],"communication":[5],"satellite":[6],"broadcasting":[7],"in":[8,14,46,142,164],"P-band":[9,166],"(367.5":[10],"MHz)":[11],"were":[12,37,106],"captured":[13],"low":[15],"Earth":[16],"orbit":[17,73,145],"using":[18,91,108],"simple":[20],"dipole":[21],"antenna.":[22],"A":[23],"delay-Doppler":[24],"map":[25],"(DDM)":[26],"was":[27],"generated":[28,107],"through":[29],"autocorrelation.":[30],"Estimates":[31],"of":[32,42,52,59,77,88,102,111,125,136,157,161,176],"the":[33,40,43,47,78,86,95,115,123,129,134,139,143,158],"specular":[34],"point":[35],"delay":[36],"obtained":[38],"lag":[41],"second":[44,81],"peak":[45],"DDM":[48,82],"with":[49,68],"bias":[51],"239.4":[53],"m":[54,61,63],"and":[55,80,98,138,146,178],"standard":[57],"deviation":[58],"44":[60],"(12":[62],"over":[64],"frozen":[66,96],"lake)":[67],"respect":[69],"to":[70,152,173],"predicted":[72,90],"model.":[74],"Relative":[75],"magnitudes":[76],"first":[79],"peaks":[83],"fell":[84,121],"within":[85,122],"range":[87,110,124],"values":[89,113,127],"dielectric":[92],"models":[93],"for":[94,114,128],"ground":[97],"lake.":[99],"Lastly,":[100],"retrievals":[101],"surface":[103],"reflection":[104],"coefficient":[105],"realistic":[112],"transmitter":[116],"link":[117],"budgetG/T,":[118],"these":[119],"also":[120],"possible":[126],"antenna":[130],"gain":[131],"pattern.":[132],"Given":[133],"lack":[135],"calibration":[137],"large":[140],"uncertainties":[141],"receiver":[144],"attitude,":[147],"this":[148],"agreement":[149],"is":[150],"sufficient":[151],"conclude":[153],"successful":[155],"demonstration":[156],"fundamental":[159],"principle":[160],"single-antenna":[162],"reflectometry":[163,167],"P-band.":[165],"may":[168],"offer":[169],"new":[171],"approach":[172],"remote":[174],"sensing":[175],"sub-canopy":[177],"root-zone":[179],"soil":[180],"moisture.":[181]},"counts_by_year":[{"year":2026,"cited_by_count":1},{"year":2025,"cited_by_count":2},{"year":2024,"cited_by_count":1},{"year":2023,"cited_by_count":1}],"updated_date":"2026-07-29T09:40:50.615796","created_date":"2025-10-10T00:00:00"}