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MIRI in a nutshell

Bart Vandenbussche

KU Leuven MIRI team meeting

Leuven, 20 june 2013

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JWST elements

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Integrated Science Instrument Module (ISIM) - Located inside an OTE provided ISIM Enclosure

- Contains 4 Science Instruments (NIRCam, NIRSpec MIRI, FGS / TF)

ISIM Electronics Compartment (IEC)

Spacecraft Bus- Contains traditional “ambient” subsystems

Solar Array

Thermal Region 2- Components maintained at

ambient temperatures on cold

side of the observatory

Thermal Region 1- Components cooled

to cryogenic temperatures

Thermal Region 3 - Components maintained at ambient temperatures

Sunshield (SS)- 5 layers to provide thermal

shielding to allow OTE and ISIM to passively cool to required

cryogenic temperatures

SS Layer 5

SS Layer 1

MomentumTrim-Tab

Optical Telescope Element (OTE)- 6 meter Tri-Mirror Anastigmatic - 18 Segment Primary Mirror

OTE Backplane/ ISIM Enclosure

OTE DeploymentTower

OTE SecondaryMirror

OTE Primary Mirror

Aft Optics Subsystem

STOWED / DEPLOYED configuration

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21.197 m

10.661 m

6.600 m

6.100 m

14.625 m

Deployed Configuration

Stowed Configuration

4.472 m

JWST in the Ariane 5 fairing

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D

XLV

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

-0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4

Launcher Y axis (m)

Lau

nch

er Z

axi

s (m

)

Allowable for JWST per CNES 4/08

Tolerance Request

25° clocking angle

(-0.138m,-0.015m)

(-0.042m,-0.069m)

(-0.100m,-0.096m)

(-0.138m,-0.015m)

(-0.105m, 0.140m) (0.115m, 0.140m)

(0.115m, -0.085m)

(-0.105m, -0.085m)

JWST space and ground segment

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L2 Transfer Trajectory

Ariane 5 UpperStage Injects JWSTInto Direct Transfer

Trajectory

S-Band Tlm Link ( 2Kbps)S-Band Ranging

S-Band Tlm Link ( 2Kbps)S-Band Cmd Link (0.25 Kbps)

S-Band Ranging

Observatory – Upper StageSeparation

Observatory Deployments- Solar Array

- High Gain/ Medium Antennas- Sunshield

- Optical Telescope Element

Communications Coverage ProvidedFor all Critical Events

Deep Space Network

Space Telescope Science InstituteScience & Operations Center

GSFC Flight Dynamics Facility

Ariane 5Launch System

NASA Integrated Services Network

Ariane PPF S5

CommunicationsServices for Launch

(TDRS, ESA, …)

L2 Point

L2 Lissajous Orbit

One 4 Hour Contact with the Ground Every 12 HoursKa-Band Science Link ( Selectable 7, 14, 28 Mbps)

S-Band Tlm Link (Selectable 0.2 - 40 Kbps)S-Band Cmd (Selectable 2 and 16 Kbps)

S-Band RangingObservatory /LV Clocking

Angle

Integrated Science Instruments Module ISIM

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JWST Thermal

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Observatory Core Area- ISIM Electronics Compartment (IEC)

- Sunshield Close-Out- Deployed Tower Assembly

- MIRI Cryo-Cooler Refrigerant Deployed Line Assembly (RLDA)

Sunshield MembraneManagement Subsystem

Backplane Support Frame (BSF)

Cryogenic RadiatorsOTE “BIB”

OTE “Frill”

MIRI Radiative Shield

MIRI subsystems

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JWST instruments

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MIRI

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MIRI overview

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MIRI Imager MIRIM focal plane layout

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MIRIM filters

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Filter name λ(μm) Δλ(μm) Comment

F560W 5.6 1.2 Broad Band

F770W 7.7 2.2

F1000W 10 2 Silicate, Broad Band

F1130W 11.3 0.7 PAH, Broad Band

F1280W 12.8 2.4 Broad Band

F1500W 15 3 Broad Band

F1800W 18 3 Silicate, Broad Band

F2100W 21 5 Broad Band

F2550W 25.5 4 Broad Band

F2550WR 25.5 4 Redundant Filter

FND Neutral Density For Coron. Acquis.

F1065C 10.65 0.53 Phase mask, NH3, silicate

F1140C 11.4 0.57 Phase mask, cont. or PAH

F1550C 15.5 0.78 Phase mask, cont.

F2300C 23 4.6 Focal Plane Mask, Debris Disk

OPAQUE Blackened Blank N/A For Darks

Coronograph

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Imager filter wheel

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Low resolution spectrograph

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MIRIM summary

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Calibration sources

Injected through hole in pupil plane image

Hot filament, non-imaging flux concentrator.

One for MIRIM, one for MRS

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Medium Resolution Spectrometer - MRS

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Spectrometer pre-optics

LT: light trapBF: blocking filter

Dichroics on 2 dichroic wheel assembliesWheel 1: 1a / 1b / 1c

Wheel 2+3: 2a+3a / 2b+3b / 2c+3c

MRS dichroic filtering scheme

System transmissions:

S[1a] = (1 - t[1a]) * t[blocking1]S[1b] = (1 - t[1b]) * t[blocking1]S[1c] = (1 - t[1c]) * t[blocking1]S[2a] = t[1a] * (1 - t[2a]) * t[blocking2]S[2b] = t[1b] * (1 - t[2b]) * t[blocking2]S[2c] = t[1c] * (1 - t[2c]) * t[blocking2]S[3a] = t[1a] * t[2a] * (1 - t[3a])S[3b] = t[1b] * t[2b] * (1 - t[3b])S[3c] = t[1c] * t[2c] * (1 - t[3c])S[4a] = t[1a] * t[2a] * t[3a])S[4b] = t[1b] * t[2b] * t[3b])S[4c] = t[1c] * t[2c] * t[3c])

System transmissions from component dichroic transmission fts measurements

MRS channels

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MRS Anamorphic pre-optics + IFU

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Anamorphic pre-optics (APO)

assymetric magnification square input field to rectangular image on slicer

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IFU

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Spectrometer main optics

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Gratings are on the same wheels as dichroics

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MRS IFU

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MRS focal plane arrays

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MRS cube reconstruction

D2c calibration file: camera (x,y) to (lambda, s/c

MRS field and spatial resolution

Channel Wavelength Pixel Size Slice Width Slices FOV Resolving Power

µm arcsec arcsec # arcsec21 5.0 - 7.7 0.196 0.176 22 3.00 x 3.87 2400 - 37002 7.7 - 11.9 0.196 0.277 16 3.50 x 4.42 2400 - 36003 11.9- 18.3 0.245 0.387 16 5.20 x 6.19 2400 - 36004 18.3 - 28.3 0.273 0.645 12 6.70 x 7.73 2400 - 3600

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MRS summary

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Detectors: Focal Plane Module (FPM)

Raytheon Si:As 1024x1024 BIB detectors

SB305 ROIC

INTEGRATION RAMPS

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2.7 or 27 secnds(fast/slow mode)

(for full frame)

Subarrays

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Time between two frames depends on size subarray

REFERENCE PIXELS

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REFERENCE OUTPUT

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LVL1 VERSUS LVL2

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LVL 1 LVL2

LVL2 STRUCTURE

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LVL2 EXTENSIONS

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