Project FAST- Five hundred meter Aperture Spherical radio Telescope
Project FAST- Five hundred meter Aperture Spherical radio Telescope
Project FAST- Five hundred meter Aperture Spherical radio Telescope
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Neutral hydrogen (HI) surveyCosmic history is written in the characters of weakHI line emission. To read this encyclopaedia, a supersensitive telescope is requiredBlind detection of HI clouds with an interference-freeobserving period of 1h, z~0.7Warm HI shell around AGN, the detection range limitin a moderate integration time, z~35
Kravtsov - Simulation ondark matter distribution in anormal galaxyXuelei Chen –Estimated<strong>FAST</strong> detection sensitivity of1 min & 1 hLine width 30km/s,S/N -106
Duffy et alNumber of galaxiesto be detected perday (18h) using<strong>FAST</strong> 19 beamswith different sanrange---- 6 sec---- 60 sec---- 600 sec---- 6000 sec---- 60000 sec7
<strong>FAST</strong> Pulsar SurveyThere are ~ 6 X 10 4 detectable pulsars inthe Galaxy, half is in <strong>FAST</strong> sky~10 4 pulsars• Rare objectsExotic stars – quark matterPulsar-BH binary….• Stellar evolution before SN• ISM map of unprecedenteddetails8
A ‘master’ of VLBI networkBonn100Chinese station<strong>FAST</strong>VLBA 80 μJyHSA 5.5 μJyHSA+<strong>FAST</strong> 3.1 μJyMuch longer source on timeIf <strong>FAST</strong> joined VSOP-ground VLBIEquivalently a 100 m in space9
Early sciences with <strong>FAST</strong>– bilateral meeting in JBO• HI – small scale deep survey of H-z• Pulsar – BH binary• M31 – extragalactic pulsars• Survey more pulsars in clusters, more about this by Scott• OH masers at z ~ 1• Lines in Orion e.g. C20H10 ? By DiFollow-ups of LOFAR/ASKAP ….Make use of the whole 500maperture by adopting a longlinear feed to achieve ?10
2. General Technical Specification<strong>Spherical</strong> reflector:Radius~300m, <strong>Aperture</strong>~500m, Openingangle 110~120°Illuminated aperture:D ill=300mFocal ratio:f/D =0.467Sky coverage:zenith angle 40°(up to 60°with efficiencyloss) tracking hours 0~6hFrequency:70M ~ 3 GHz(up to 8GHz in future upgrading)Sensitivity (L-Band) :A/T~2000, T~20 KResolution (L-Band) :2.9′Multi-beam (L-Band) :19, beam number of future FPA >100Slewing:
★ S 2★ S 1Optical geometryO12
Opening angle - sky coverageSky coverageZA 30 degZA 40 degZA 60 deg<strong>FAST</strong> ZenithZA 56 degSky coverage<strong>FAST</strong> vs. Arecibo13
Opening angle - sky coverage (cont.)300mZA205m30º 60ºIf FPA technology could form an irregular beam tofully match the desired portionWe can have a large single dish ~ 200m at zenith 60°We are interested to have the Roger’s talk on FPA14
Frequency range0.13 0.327 1.42 3458(GHz)In layout 2000First phaseSecond phaseHI surveying70MHzz~20EoRPulsar300MHzHCOOHCH3OH OH(4) HC5N(4) CH(4) CH4Water hole5.2GHzH2CO(6)VLBI17 LinesSETIS BandC BandX BandSpace science15
ObservatoryObservatory buildingComputing centerDisaster prevention3.Technical plan– critical technologyReceiversReceiversBackendOptical fiberMeasurementsMark stoneLaser total stationPhotogrammetryField busSiteActive ReflectorFeed supportMeasurementsReceiversObservatoryEarth workDrainageExplorationSiteTension monitoringWinchesElementsMain cable netActive ReflectorCablesAB-rotator & StewartCapstanTowerFeed support 16
3.Technical plan– critical technologySiteActive reflectorFeed supportMeasurementsReceiver17
Site Surveying in GuizhouGuiyangLocation: N25.647222ºE106.85583°Site: the Karst region in south Guizhou Province18
Quick Bird Fly Oct. 6, 200519
3.Technical plan– critical technologySiteActive reflectorFeed supportMeasurementsReceiver20
Central part of sphere is close to paraboloid as f/D is properMinimized deviation is 0.67m as f/D ~ 0.467 RMaximum slope of deviation curve gives maximum rate 0.7mm/sdeviation along radial direction (<strong>meter</strong>)1.61.20.80.400.40 20 40 60 80 100 120 140 160distance from center of aperture (<strong>meter</strong>)F=0.467RF=0.477RF=o.450RMain reflector is composed of small element units~ 2000 hexagons of 15m – rms 4mm~ 4600 triangles of 11m – rms 2.2mm21
~2400 winches~4600 panelsAdaptive cable-meshTwo realizationsof main reflectorSolid panel-actuator~2000 panelsandactuators22
3.Technical plan– critical technologySiteActive reflectorFeed supportMeasurementsReceiver23
Feed supportmechanical-electronic-optical integrated design• Focal cap dia<strong>meter</strong> 206m• Cabin in total ~30t• Load on lower plate ~3t• Maximum tracking 11.6mm/s★ S 1• Slewing 400mm/s• Position error
Three main parts of cabin suspension• Cable network - first adjustable system• Stewart - secondary adjustable system• Close loop control25
3.Technical plan– critical technologySiteActive reflectorFeed supportMeasurementsReceiver26
Measurement – precise, quick and in long distanceTask 1: 3-D spatial positions of focus cabin• Large working range up to 300 m• Errors ~1 mm• Sampling rate > 10 HzTask 2: profiles of main reflector• Number of targets ~2400• ~1000 in illuminated area• Accuracy 1~2mm• Sampling interval 10 sec ~ few min27
PhotogrammetrySurveying reflector profile1000 nodes withinilluminated areato be scanned in real-timeperiod ~ 1 min28
3.Technical plan– critical technologySiteActive reflectorFeed supportMeasurementsReceiver29
9 sets of <strong>FAST</strong> receivers NAOC - JBONo Band (GHz) Beams Pol. CryoTsys(K)1 0.07 – 0.14 1 RCPLCP2 0.14 – 0.28 1 RCPLCP3 0.28 – 0.56 1 or multi RCPLCP4 0.56 – 1.02 1 or multi RCPLCP5 0.320 – 0.334 1 RCPLCP6 0.55 – 0.64 1 RCPLCP7 1.15 – 1.72 1 L wide RCPLCP8 1.23 – 1.53 19 LnarrowmultibeamRCPLCP9 2.00 – 3.00 1 RCP/LCPno1000no400no150yes60no200yes60yes25yes25yes25ScienceHigh-z HI(EoR),PSR, VLBI, LinesHigh-z HI(EoR),PSR, VLBI, LinesHigh-z HI(EoR),PSR, VLBI, LinesSpace weather, Low frequency DSNHigh-z HI(EoR),PSR, VLBI, LinesExo-planet scienceHI,PSR,VLBIEarly sciencesHI,PSR,VLBIEarly SciencesHI,PSR,VLBI,SETI,LinesHI and PSR survey, TransientsPTA, DSN, VLBI, SETI30
Receiver -- Schematic DiagramFeed+ polarizerLNA Mixer E/OO/EHIlinePulsarVLBISETImultiReceiverDiagnostics31
4. Feasibility study of critical technologiesFeasibility study of critical technologies started since 1994.More than a <strong>hundred</strong> scientists and engineers from 20 institutionsThe project is ready to move on to actual programming.• Fast sciences• Site surveying• Active main reflector -- Solid panel-actuator design- Adaptive cable-mesh design• Feed support- Cables + stabilizer- Cables + rotation mechanism + stabilizer• Measurement• Receiver32
Exploration in depression site and therock-soil samples from ground33
eaking load experimentcablesnodes34
Prototyping the back-structureof reflector elementSimple, enable mass production, strong weather resistance.10kg/m 2 is a up-limit边 缘 构 件bowstring刚 性 构 件Rear rib: hollow rectangular tube, Z-shaped …Spatial truss backup (costly)35
Prototyping rear ribLess than 1mm curved, gravity – no gravityjoint Adjust screw Bow-stringSingle rear ribSingle rear rib with bow-string36
Spatial truss backup (costly)Deformation 2.5mm by gravityAdjust screwjointExpandedaluminum meshPerforated aluminum sheetSpacial truss back structure37
Prototyping the winches• worm-wheel/ball screw• cycloidal-pin wheel /sliding screw• serial worm wheel/ball screw• cycloidal-pin wheel /worm wheel /sliding screw=830行 程 830拉 伸 长 =1215尾 销 端编 码 器 护 罩编 码 器 出 线 口联 接 法 兰收 缩 长 =385接 近 开 关日 本 减 速 电 机接 近 开 关 护 罩38
Prime focus position controlExperiment on the cable39supporting system, Dec. 2001
Dynamic experiment on Stewart stabilizer, Sept. 200240
NCollaboration with MT and TUDOptimization of cable tension force:Max.: 220KN;Min.: 100KNDesign of counter-weights:travel range reduction: R=2rcounter-weight=[(220+100)/2]*2=320KN(100KN)motor gearbox bearingCapstan drum (R)Counterweightdrum(r)41
1st harmonic (0.182455Hz)2nd harmonic (0.4247Hz)Vibration modes and Bodediagram of suspension cables42
• under the wind 8m/s, 1st adjustmentreaches control accuracy 8mm• as the stabilizer is switched onaccuracy 4mm• spectra - 0.18HzTotal weight of cabin ~ 30treceivers 4Stabilized platform 2actuators 1,5X-Y Frames 4Y- positioner base 4cladding 8Top frame – star truss 4total 27,543
Most precise laser rangerAPIMaximum rangingdistance – 120mTCRA2003: 1+1ppmAPI: 0+5ppmADM-IFM error (mm0.5000.4000.3000.2000.1000.000-0.100-0.200-0.300ADM specaverageADM spec-0.4001.11.0#3449 Tracking ADM intensity-0.5000 10000 20000 30000 40000 50000 60000 70000 80000 90000 100000 110000ADM dis tance (mm)0.9ADM Intensity (V)0.80.70.60.50.40.30.20.1To expand the rangingReshape the beamNew detector – 150VAvalanche breakdown voltage0.00 10000 20000 30000 40000 50000 60000 70000 80000 90000 100000 110000ADM Distance (mm)44
CCD:20Hz;0.5cmDGPS:10Hz;1cmLaser Tracker:1KHz;0.05mmIMU:0.1°Measuring45Total station
Receiver layout• Main focus, -13dB, G/T ~ 2000 m 2 /K• 70MHz - 1GHz,4sets 1-octave band• L – one wide band receiver19 multi-beam receivers• 2 - 3GHz scaled JBO C - band1.23-1.53 GHz multi-beamATA 0.5 – 11GHzLOFAR 120 – 240MHzf - range :1.23-1.53 GHzfeed:19 coaxial hornsf/D: 0.46, less curved than ParkesLNA: HEMT cooledIF:optical fiber cabin - groundBackend:HIPulsarTransientsWSRT 115 – 180MHz46
<strong>FAST</strong> model construction process1. tower2. girder ring3. cementdepression5. actuator4. cable & node
HI was observed using 50mmodel in Sept 2006.48
5. Current state of <strong>FAST</strong> projectTotal budget ~ 688 millions ¥ (600 millions admitted)Budget in feasibility report is ~ 700 millions ¥<strong>Project</strong> time 5.5yrs from foundationBudget pie41%11%5%1%4%10%5%6%10%7%- Main reflector-Earthwork- Feed support- Receivers- Measurement and control- Infrastructures-Design- Observatory and facilities- Site investigation- Unexpected49
Approval appears on SKA webpagehttp://www.skatelescope.org/pages/page_newfront11.htm50
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