The Tandem-L Formation

Transcription

1 The Tandem-L Formation G. Krieger, I. Hajnsek, K. Papathanassiou, M. Eineder, M. Younis, F. De Zan, P. Prats, S. Huber, M. Werner, A. Freeman +, P. Rosen +, S. Hensley +, W. Johnson +, L. Veilleux +, B. Grafmueller *, R. Werninghaus, R. Bamler, A. Moreira German Aerospace Center (DLR), * EADS Astrium GmbH, + Jet Propulsion Laboratory

2 Main Mission Objectives: Mapping the Dynamic Earth Biosphere 3-D vegetation monitoring measurement of forest height and structure global inventory of above ground forest biomass vegetation disturbances and biomass changes Geo/Lithosphere deformation measurements understanding earthquake and volcano eruption cycles quantifying the magnitude of events determination and forecasting the probability of events Hydro/Cryosphere observation of ice structure and its changes measurement of soil moisture and surface water changes monitoring of ocean currents and wave field dynamics 2

3 3D Structure Mode Polarimetric SAR Interferometry (Pol-InSAR/single-pass) ~ 30 m Estimation of the vertical structure of volume scatterers: Vertical structure components are resolved by means of their polarimetric signature; The (height) location of the resolved structural components is estimated by interferometric measurements. 3

4 Performance Prediction: 3-D Structure Mode (Pol-InSAR) k z = 0.05 rad/m (h amb = m) k z = 0.2 rad/m (h amb = 31.4 m) k z = 0.1 rad/m (h amb = 62.8 m) Model Model = RVoG RVoG = db/m db/m sys 0.9 sys = 0.9 N look 30 look = 30 multiple acquisitions with different baselines 4

5 Deformation Mode Earthquakes measurement of deformations of mm cm Volcanoes λ/2 12 cm Subsidence Land & Sea Ice systematic multi-temporal acquisitions (image stacks) 5

6 Performance Example: Deformation Mode combined error T T = 8 days days = days days a 10 mm a = 10 mm SNR SNR = db db N look 32 look = 32 Conclusions: SNR temporal decorrelation atmosphere as many looks as possible (high res.) as many data takes as possible SNR not so critical (e.g. coarse quant.) 6

7 Mission and System Requirements measurement of 3-D structures (vegetation) & their evolution monitoring of geo-dynamics (deformation) with high temporal resolution L-band SAR single-pass interferometry (satellite formation) full polarimetry wide-swath and highresolution SAR imaging high downlink capacity (e.g. Ka-band network, geostationary relay, ) 7

8 Mission Concept two complementary imaging modes in alternating operation polarimetric cross-track interferometry differential repeat-pass interferometry 8

9 Mission Concept 9

10 Equator: Horizontal Baselines (Bistatic Mode) h=800 km h=700 km h=600 km k z =0.2 rad/m (h amb = 31.4 m) B h = m k z =0.1 rad/m (h amb = 62.8 m) k z =0.05 rad/m (h amb = m) 10

11 Ascending Node Drift by Different Inclinations (h=700km) Δi 2 km (Δv<2.4 m/s) 1 km (Δv<1.2 m/s) 500 m (Δv<0.6 m/s) ΔΩ 200 m (Δv<0.3 m/s) mission concept with varying baselines by slight inclination shifts 11

12 Baselines at high latitudes (bistatic mode) inclination differences between the orbital planes Δi horizontal baseline vertical component from eccentricity vector differences (limited) radial baseline Δe use of alternating bistatic (monostatic baseline) narrower swaths: optimum positioning vs. incidence 12

13 Tandem benefits for repeat-pass interferometry frozen orbit satellite variable orbit satellite use (zero baseline) looking right looking right DEM from single-pass (L-band!) right-looking series looking right looking left, baseline fixed for 2 repeat-pass cycles uninterrupted rightlooking series interferogram from leftlooking geom. (3D) looking left looking left time series from leftlooking geom. (3D) DEM from single-pass looking right, reduced bandwidth, full swath looking right, large bandwidth, reduced swath conflict resolution with other applications 13

14 Digital Beamforming with Reflector Antennas Digital Control & Processing digital feed array with T/R modules 14

15 Digital Beamforming with Reflector Antennas digital feed array with T/R modules 15

16 Digital Beamforming with Reflector Antennas digital feed array with T/R modules 16

17 Digital Beamforming with Reflector Antennas 17

18 Digital Beamforming with Reflector Antennas Rx Tx + Rx Tx A D DBF / VQ A D Large Large reflector aperture enables: very very high high sensitivity improved range range ambiguity suppression less less losses losses at at swath swath border border efficient implementation of of advanced DBF DBF modes modes 18

19 Multiple Swath Imaging increased simultaneous coverage gaps gaps within within the the wide wide swath swath blind ranges swath echo h=760km A D A D A D A D A D A D A D blind ranges (for fixed PRF) use e.g. 2nd pass to fill in blind ranges 19

20 Multiple Swath Imaging without Gaps slow slow PRF PRF variation: longer longer burst burst lengths lengths improved performance assumes nadir nadir suppression by by DBF DBF blind ranges move across swath! h=750km burst length 20

21 Systematic Shift of Blind Ranges blind ranges 21

22 Large mapping capability TanDEM-X 1 global acquisition / year Tandem-L 2 global acquisitions / week Swath Swath width: width: km km Acquisition Acquisition time: time: 3 min min // Orbit Orbit Day Swath Swath width: width: km km Acquisition Acquisition time: time: min min // Orbit Orbit 22

23 Tandem-L provides an innovative and highly capable SAR instrument that could in principle satisfy all science requirements in a single SAR mode 350 km quad 85 high resolution (~ x 25 m 2 ) - huge data rate: R 1.1*85 MHz * (8+8) bit/sample * 2 channels * 4 beams 12 Gbit/s - huge data volume (mapping of all landmasses: ~ 30% duty cycle) V 12 Gbit/s * 24h * 30% * 2 SAT 78 TByte/day optimize science return for a given data rate & volume priority areas trades (BAQ quantization vs. resolution vs. number of acquisitions) hybrid SAR modes 23

24 Conflicting areas (Vegetation & Deformation) 100m 75m 50m 25m 0m 24

25 Conflicting areas (Vegetation & Deformation) 100m 75m 50m 25m 0m 25

26 Conflicting areas (Vegetation & Deformation) 100m 75m 50m 25m 0m 26

27 Hybrid SAR Modes to resolve contradicting user requirements Tx - Spectrum f high resolution quad pol (Pol-InSAR) low resolution single pol (D-InSAR InSAR) 27

28 Tandem-L Summary Abholzung Aufforstung Waldbiomassenänderung Biosphäre - global monitoring of bio-, geo-, cryo-, and hydrosphere processes with high temporal and spatial resolution Vulkanismus Erdbeben Hangrutschungen Geo/Lithosphäre Eisausdehnung Bodenfeuchte Überschwemmungen Hydro/Cryosphäre - tandem satellite formation for the measurement of 3-D structures and their spatiotemporal evolution - systematic data acquisition strategy with complementary imaging modes - employment of highly innovative radar techniques to improve coverage, resolution, and repetition frequency 28

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30 Backup Slides 30

31 full bandwidth (e.g. 85 MHz) for high resolution fault imaging low bandwidth (e.g MHz) for uninterrupted large scale deformation time series Peripheral Vision wide swath with low to medium resolution Foveal Vision narrow swath with high resolution 31

32 Tandem-L: Further Potentials Digital Terrain Model acquisition of a global DEM that is complementary to the X-band DEM (digital terrain and surface model) Commercial Utilization derivation of advanced higher-level products & synergy with X-band data (Infoterra) Wide Range of Additional Applications (Selection) - measurement of soil moisture and surface roughness - observation of thaw and freeze cycles - determination of ice volume structures and their change - measurement of annual changes in ice mass balance - measurements of sea ice thickness - measurement of ocean currents and wave heights - water level measurements beneath the vegetation - detection of embankment and dike damages - desertification and wetland deterioration - land classification (vegetation, land use, ) - monitoring of land subsidence - observation and prediction of land slides - agriculture (vitality, growth,...) - surveillance of logging and reforestation - detection of forest damages (storm, fire, ) 32

33 Biosphere Geo-/Lithosphere Science Product Forest Height Above Ground Biomass Vertical Forest Structure Coverage all forest areas Product Resolution 50 m (global) 20 m (local) 100 m (global) 50 m (regional) 50 m (global) 20 m (local) Product Accuracy ~ 10 % ~ 20 % (or 20 t/ha) 3 layers Underlying Topography 50 m < 4 m Plate Tectonics Volcanoes all risk areas all land volcanoes 100 m (global) < 20 m (fault) 1 mm/year (after 5 y) m 5 mm/week Landslides risk areas 5 20 m 5 mm/week Subsidence urban areas 5 20 m 1 mm/year Cryo- & Hydrosphere Glacier Flow main glaciers m 5 50 m/year Soil Moisture selected areas 50 m 5 10 % Water Level Change regional 50 m 10 cm Snow Water Equivalent local (exp.) m % Ice Structure Changes local (exp.) 100 m > 1 layer Ocean Currents prio. areas ~ 100 m < 1 m/s All Digital Terrain & Surface Model global ~ 20 m (bare) ~ 50 m (forest) 2 m (bare) 4 m (veg.) 33