Presentation on theme: "In-situ Radar for Asteroid Characterization and Altimetry"— Presentation transcript:
1 In-situ Radar for Asteroid Characterization and Altimetry NASA Asteroid Initiative Idea Synthesis WorkshopLunar and Planetary Institute, Houston, TXSept 30 – Oct 2, 2013In-situ Radar for Asteroid Characterization and AltimetryMark HaynesRadar Science and Engineering (334c)Jet Propulsion Laboratory, California Institute of TechnologyCL#This document has been reviewed and determined not to contain export controlled technical data.(c) 2013 California Institute of Technology. Government sponsorship acknowledged.
2 Overview In-situ Radar for ARM Radar features Integrated sensing systemAvionics toolSecondary scienceRadar featuresSelf-illumination, shadow/dust independentFast, near or far rangeRange, Doppler, physical scatteringRFI subsections2. Asteroid Redirect Mission: b) Integrated sensing system … rendezvous, proximity operations … characterize size, shape, mass and inertia properties, spin state, surface properties, and composition….closed-loop control.3. Asteroid Deflection Demonstration: c) ... sub-surface penetrating imaging...4. Asteroid Capture Mission: d) Asteroid composition, internal structure, and physical integrity will likely be unknown until after rendezvous and capture.5. Crew Systems for Asteroid Exploration: ..., prospect for resources, ...9/30/2013
3 Radar Landscape Past and Current Planetary Radar Missions and Science GoldstoneAreciboAsteroid Radio ScienceGoldstone and AreciboNEOs, planetary science (moon, Venus, Mars satellites)Planetary missions with radarAtmosphere penetrationMagellan, CassiniSoundingMRO / Mars ExpressRosetta-CONCERT radarLanding/RendezvousMSL, previous roversApollo/ShuttleEarth science remote sensingAsteroid missions (no in-situ radar)NEAR-Shoemaker, Dawn, Hayabusa, Osiris-RexCassini (Titan)Magellan (Venus)Mars Reconnaissance Orbiter(SHARAD)Mars Express(MARSIS)Rosetta (CONCERT)No in-situ radar on asteroid missions to date9/30/2013
4 Radar Sounding Map the regolith Internal structureBulk dielectric properties (density)Anchoring redirect thrusterSample and boulder returnImproved asteroid trajectory estimateRadar is only active modality capable of sub-surface imagingScan-line projection or dielectric inversion100 MHz to 2 GHz => 20m to 1m depth3 past/current sounder missionsScan-line projectionReflection MeasurementsShapeIterative Dielectric EstimationElectromagnetic Scattering ModelScan-line projection(anatomy)Measurement pointsRosetta - CONSERTMARSIS and SHARADDielectric inversion(physical properties)Herique, Alain, and Wlodek Kofman. "Definition of the consert/rosetta radar performances." In EGS General Assembly Conference Abstracts, vol. 27, pVoxelized dielectric model9/30/2013
5 Shape reconstruction algorithm TomographyDelay-Doppler TomographyDelay measures rangeIn-situ delay-Doppler asteroid tomography“Goldstone analog”Asteroid size, shape, spin, range to target, relative motionFrequency: 1 to 35 GHz => 1 to 0.1 m resolutionCoarse antenna pointingClose-loop feed back during spacecraft maneuversDifferential Doppler – monitor spin changesGPS-proxyDoppler measures motion (rotation)Delay-Doppler imagesShape - SpinShape reconstruction algorithmBusch, Michael W., et al. "Physical properties of near-Earth Asteroid (33342) 1998 WT24." Icarus (2008):GPS-proxyNew-delay DopplerTable lookup: determine spin and position2) Space craft maneuver1) Change in spin state (deflect thruster)9/30/2013
6 Rendezvous - Altimetry - Targeting Apollo: X-bandAltimetry/Landing radarReduce orbit uncertainty using delay-Doppler echoesPost impact assessmentTargeting and guidanceOn-route tomography to pinpoint impact time and locationLandingGeneral purpose rendezvous radarTry to repurpose the imaging radar for this.Impact: Same can be done optically possibly, LIDAR is outSingle spacecraft impact targeting and guidance> 100k-1M km9/30/2013
7 System Configurations Sounding antennaComm. antennaSystem configurationsSingle antenna: tomography and soundingSounding: separate UHF, VHF, or L-band antennaUse DSN comm. dish: S, X, Ka-bandPower vs. rangeEarth observation radars:Satellite (800 km) ~ 1 kW (peak)Airborne (10 km) ~ 1-20 W (peak)Close range (100 m) ~ mW (peak)On-board vs. ground based processingOn-board: scan-line sounding, altimetry, targeting, tomo.Ground-based: dielectric inversion, tomo.End-to-end system simulationTomo.Scan-linesoundingDielectric inversionOn-board processingGround processing9/30/2013
8 Summary RFI subsections 2. Asteroid Redirect Mission: … integrated sensing system …… rendezvous, proximity operations …… characterize size, shape, mass and inertia properties, spin state, surface properties, and composition ……. closed-loop control …3. Asteroid Deflection Demonstration:... sub-surface penetrating imaging ...4. Asteroid Capture Mission:… composition, internal structure, physical integrity …5. Crew Systems for Asteroid Exploration:..., prospect for resources, ...RendezvousTomographySoundingRendezvousTomographyGPS-proxyAltimetryLandingImpact AssessmentImpact guidanceSounding9/30/2013
9 Thank you Questions Mark Haynes Radar Science and Engineering (334c) Jet Propulsion Laboratory, California Institute of Technology9/30/2013
10 Rough Surface Characterization Synthetic aperture radar (SAR) to characterize rough surface propertiesCorrelation length, rms height, near-surface volume scattering (density estimation)Rough surface parameters used for thermal inertial modelingVolume fraction potentially used to estimate b (momentum multiplication factor for impact redirection)SAR requiresFully polarimetric radar (HH, VV, HV)Shape and attitude knowledgeComplementary to LIDAR rough surface estimationqincRMS heightHVSAR backscatterVolumefraction scattering~ density9/30/2013
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