SMOS Payload Performance

Transcription

1 SMOS Payload Performance Manuel Martin-Neira, Michael Brown SM-OS Project European Space Agency Josep Closa EADS-CASA Espacio and contributions from: UPC and DEIMOS SMOS project teams 1/33

2 Contents: - Basic Equations - Payload Performance ests - Performance over emperature - Image Validation - Error Budget - Future Work 2/33

3 3/33 Basic Equations Corbella Equation! " " = q j p i j i j i B pq ij B B k v u V 1 2 ), ( # # 2 2 *,, 1,, 1 ), ( ), ( ), ( 2 2! " #! "! "! " $% $% %! " $ & & & '' ( + r B q j n p i n F F! "! "! " # d d e f v u r v u j o ij ) ( 2 ~ + $ % % & ' ( ( ) * + $

4 Basic Equations Visibility Key Elements NIR V = sys, k G sys, j M Correlations PMS 4/33

5 Basic Equations Imaging (Level-1 Processor) V IDEAL G-Matrix 1.- same antenna patterns 2.- no fringe-washing = IHF { V} % $ 1 B # r 2 2 # " #! F n 2 B 5/33

6 Payload Performance ests he performance test plan of the SMOS payload included: - ests over temperature in the Large Space Simulator (LSS) - Image validation in the Maxwell EMC chamber 6/33

7 Payload Performance ests MIRAS in the Large Space Simulator 7th SMOS Workshop, Frascati, October /33

8 Performance over emperature ( C) NIR and LICEF s emperature Profile in the Large Space Simulator 35 C 35 C 30 nominal redundant nominal redundant C C 10 C hours 20 8/33

9 Performance over emperature V = sys, k G sys, j M NIR Variation over emperature emperature Drift for a 220 K Scene (K/C) 10 C --> 35 C 35 C --> 10 C NIR Unit HO WARM HO WARM AB H AB V BC H BC V CA H CA V Specification < 0.2 K/C ; 0.02 K/C with compensation 9/33

10 Performance over emperature PMS Variation over emperature 10/33

11 Performance over emperature PMS Variation over emperature 11/33

12 Performance over emperature < 0.5 % (1-sigma) V = sys, k G sys, j M 12/33

13 Performance over emperature G Variation over emperature V = sys, k G sys, j M G < 0.3 % pp (worst baseline) LICEF temperatures (same baseline) 13/33

14 Performance over emperature Phase of G and M over emperature Arg {G} = 16 pp V = sys, k G sys, j M 14/33

15 Performance over emperature Peak-to-peak phase variation of G (deg) over temperature Peak-to-peak variations within segments are most of them below 0.5 (worst baseline is 1.5 ) V = sys, k G sys, j M 15/33

16 Performance over emperature LO phase variation tracking (in-orbit calibration) - requires additional noise injection and Fourier or Spline interpolation; - to minimise impact on coverage a new 4-epoch calibration sequence is introduced; 16/33

17 Performance over emperature Frequency of noise injection to calibrate LO phase variations - LSS: sampling!6 the main period is required (i.e. 7.6 min for 45 min period); -hermal model prediction for flight: orbital period dominant, thus 1 noise injection / 16 min; - his frequency BC during the commissioning phase; - A reduction of the original short calibration to once a day would keep coverage loss < 1% 17/33

18 Payload Performance ests MIRAS in the Maxwell EMC Chamber 18/33

19 Image Validation NIR sensitivity Specification /33

20 Image Validation NIR Accuracy (using factory values) NIR antenna temperature using factory values 20/33

21 Image Validation H-V Correlation Offset (Full-pol Mode) Specification 1 21/33

22 Image Validation Correlation Offsets (1 cu = 10 4 ) Specification 22/33

23 Image Validation Relative Phase Recovery (H-pol) 23/33

24 Image Validation Other key results found in Maxwell: - PMS values are stable (gain variation < 0.2% over 12 h); - Correlations are very stable (<0.5 cu over 12 h); - Extremely marginal effects of X-band link (in practice, no effect); - No effects from Star racker (with its shielding); - All measurements show a high degree of consistency; - All LICEFs are very similar -> highly separable in phase (FwF); - Dynamic range is above 5 decades (8000 cu 0.06 cu); 24/33

25 Image Validation Imaging (Level-1 Processor) V IDEAL G-Matrix 1.- same antenna patterns 2.- no fringe-washing = IHF { V} % $ 1 B # r 2 2 # " #! F n 2 B 25/33

26 Image Validation H-pol Modified Brightness emperature = IHF { V} % $ 1 B # r 2 2 # " #! F n 2 26/33

27 Image Validation Amplification Factor % $ 1 B # r 2 2 # " #! F n 2 27/33

28 Image Validation H-pol Brightness emperature 28/33

29 Image Validation H-pol Brightness emperature in AF-FoV 29/33

30 Image Validation H-pol Intermediate Radiometric Resolution 30/33

31 Image Validation H-pol Final Image Radiometric Resolution "3 db beam 4.6 K boresight 2.3 K 31/33

32 Error Budget SRD Requirement System Parameter Specified Value SA-PDR Actual Value From IV (IDEAL reconstruction) R a,b Level-1 SM Radiometric Sensitivity 220 K 3.5 K RMS ( 00 ) 5.8 K RMS ( 32 ) 2.43 K RMS 3.98 K RMS 1.97 K RMS 3.94 K RMS R a,b Level-1 OS Radiometric Sensitivity 150 K 2.5 K RMS ( 00 ) 4.1 K RMS ( 32 ) 1.99 K RMS 3.26 K RMS 1.65 K RMS 3.31 K RMS 32/33

33 Future Work - Further detailed processing of LSS and IV - Validation of the LO calibration sequence - Consolidation of the in-orbit calibration strategy - Detailed validation of L1PP - Empty chamber image of L1PP G-matrix - Introduction of F+Gibbs/SDB Reduction in L1PP - Performance analysis based on L1PP Maxwell images 33/33