SPIRE-RAL-NOT-000615

Contents List for the SPIRE Design Description Document


1.        INTRODUCTION.. 5

1.1       The SPIRE instrument and its scientific programme. 5

1.2            Purpose of this document 6

1.3            Scope  6

2.        INSTRUMENT OVERVIEW... 7

2.1            Photometer design drivers  7

2.2            Spectrometer design drivers  7

2.2.1                Imaging photometer 10

2.2.1.1            Optical Design and FPU layout 10

2.2.1.2            Detector arrays  11

2.2.1.3            Photometer observing modes  12

2.2.2                Fourier transform spectrometer 13

2.2.2.1            Optical design and FPU layout 13

2.2.2.2            Spectrometer detector arrays  15

2.2.2.3            Spectrometer observing modes  15

2.2.3            3He cooler 16

3.     Instrument System Design. 17

3.1       The SPIRE Instrument as a System   23

3.2            Structural Design and FPU Integration. 27

3.3            Optical Design. 28

3.3.1                Common Optics and Photometer Optics  28

3.3.2                Straylight control 32

3.4            Technical design drivers  32

3.4.1                Thermal design drivers  32

3.4.1.1            Instrument temperature levels  32

3.4.1.2            Cryogenic heat loads  32

3.4.1.3            Temperature stability  33

3.4.2                Optical Design Drivers  33

3.4.2.1            Geometry  33

3.4.2.2            Optical throughput 33

3.4.3                Signal quality  33

3.4.3.1            Microphonics  33

3.4.3.2            EMC   33

3.5            Redundancy Scheme  33

4.        Subsystem Design. 34

4.1            Digital Processing Unit (HSDPU) 34

4.2            Detector Readout and Control Unit (HSDRCU) 34

4.2.1                Detector Control Unit (HSDCU) DKG   34

4.2.2                FPU Control Unit (HSFCU) DKG   35

4.2.2.1            HSSCU   35

4.2.2.2            HSMCU   35

4.3       RF Filters DKG.. 35

4.4            JFET units DKG.. 35

4.5            Bolometric Detector Arrays  35

4.5.1                Principle of semiconductor bolometers  35

4.5.2                SPIRE bolometer performance requirements  35

4.5.3                SPIRE bolometer design and specifications  36

4.5.4                Bolometer readout electronics  36

4.5.5                Feedhorns and bolometer cavities  37

4.6            Mirrors  38

4.7            Filters, beam splitters  38

4.8            Internal calibrators   MJG/PCH.. 38

4.9            Beam Steering Mechanism (BSM) 38

4.10            Spectrometer Mechanism.. 41

4.11     FPU structure  41

4.12        3He Cooler 41

4.13            Thermal staps. 41

4.13.1                2-K to 4-K   41

4.13.2                300 mK   41

4.14     FPU thermometry. 41

4.15            Harness  41

4.16            Shutter 41

5.     Instrument Operating Modes. 42

5.1            Spacecraft pointing  42

5.2            Spacecraft movements during SPIRE observing. 43

5.2.1                Nod  43

5.2.2                Raster 43

5.2.3                Line Scan  44

5.3            Photometer Observatory Functions. 45

5.3.1                Point Source Photometery (POF1 and POF2) 46

5.3.2                Jiggle Mapping (POF3 and POF4) 46

5.3.3                Scan mapping (POF 4 and POF5) 47

5.3.4                Photometer peak-up (POF7) 47

5.3.5                Operation of photometer internal calibrator (POF8) 47

5.4            Spectrometer Observatory Functions. 48

5.4.1                Point source spectrum (SOF1) 48

5.4.2                Fully-sampled spectral map (SOF2) 48

6.     Spire Sensitivity Estimation. 48

7.     Criticality Analysis. 52

8.        References  52

9.     List of Annexes. 54