STScI, Baltimore, MD02-1 18th May 2006
The JWST Mid-Infrared Instrument: MIRI
Margaret Meixner
MIRI Science Team Member
MIRI instrument support scientist
Based on Slides presented by the MIRI team as noted.
STScI, Baltimore, MD02-2 18th May 2006
MIRI System Flight Components (Goodson & Renouf& Larson)
Plus the following Harnesses that mounted to ISIM:
OM to ICE Harnesses OM to FPE Harnesses Cryo-cooler to FPE Harnesses
Optics Module(including Thermal Strap
Assembly) FSWFPE
ICE
Precooler Compressor
JT Compressor
Cooler Control Electronics
Relay Switch Assembly
“Heat Sink Assy” (Recuperator, valves)
Coldhead Environmental Shield
JT Pre-cooler Recuperator
3-Stage Pulse Tube Pre-cooler Coldhead
RLDA (part of CTA)
OM Stage (6K heat exchanger(s)
Cooler
STScI, Baltimore, MD02-3 18th May 2006
MIRI OBA Struct./Mech. Model tested (Wright/ Glasse)
STScI, Baltimore, MD02-4 18th May 2006
MIRI OM, Cooler and ISIM (Larson)
OMS will mount at the Thermal Strap assembly interface to the OM Primary Structure lower deck component
Figure shows notional Heat Exchanger mounted to TSA thermal interface
Heat exchanger position is well inside MLI support structure and MLI
Cooler refrigerant line treated like harness
One or more standoff brackets designed to accept P-clip or similar conventional attachment (green item in right figure below)
OMS
Refrigerant line support
Notional HSA
Preliminary refrigerant line routing
STScI, Baltimore, MD02-5 18th May 2006
Overview MIRI Cooler TRL-6 Plan (Larson)
Technology to be Demonstrated:Operation of the 6K Cooler system in JWST environment at JWST performance levels
TRL-6 Item Description:Engineering grade Cooler components: Cold Head (remote), field joints, compressor(s), and pre-cooler cold end, with DM drive electronics
Key Items to be Proved:Performance: Base temperature under remote heat load, leak rate, gas purity, cooling efficiency, noise, exported vibrationEnvironment: Cryogenic operating temperatures, applied heat loads, vibration, radiation
Current Status:- Current TRL is 4 to 6 depending on component- Technology development program has proven:
- Remote cooling capability- Cooler compressor(s)
- Cooler vendor selection is complete and on contract
MilestonesPlanned
Completion Date
• Initial remote cooling testing 1/13/06
• Cooler vendor selection 2/28/06
• Cold Head Assembly complete, tested 6/30/06
• Cooler Tower Assembly (field joints) complete and tested (vibration, thermal cycle)
7/14/06
• Compressor Assembly complete, tested 8/25/06
• Achieve TRL-6, system test complete 12/15/06
STScI, Baltimore, MD02-6 18th May 2006
Instrument Functions (Wright)
Multiple Optical Configurations Photometric Imaging over a wide field. Coronagraphy between 10 and 27 m. Low Resolution (R = 100) Slit Spectrosopy of Single Sources (5 – 10
m). Medium Resolution (~ 100 km/sec velocity resolution) Integral Field
Spectroscopy from 5 to 28.5 m.
Diffraction limited image quality. To maximise the sensitivity on point sources. To exploit JWST’s spatial resolution (resolve ~ 1 kpc at all
redshifts).
Optimised Sensitivity
The minimum noise level is bounded by the instrument environment (thermal emission from the sky and telescope), so MIRI must
Have high Photon Conversion Efficiency (Optical Transmission x Detector QE).
Spatial and Spectral Passbands matched to the science targets.
STScI, Baltimore, MD02-7 18th May 2006
Medium Resolution Spectrometer
MIRI Allocation
MIRIM FOV
Imager
4QPM15.5µm
4QPM11.4µm
4QPM10.65µm
Lyot Mask23mLow Resolution
Spectrometer
MIRI Fields of View (Glasse)
STScI, Baltimore, MD02-8 18th May 2006
Imager - Optical Requirements (Wright)
Requirements:
> 2 square arcmin field of view, with a 0.11 arcsecond pixel scale
Image Quality
> 58% of light within first dark ring of model telescope PSF
Strehl ratio > 85 % longward of 5.6 m
Coronagraphy in 4 filter bands (see Design Doc. for details)
R=100 Spectroscopy
Simulated NIR JWST field (Myungshin Im 1998)
1.3 arcmin
1.7 arcminDesign:
STScI, Baltimore, MD02-9 18th May 2006
The MIRI Imager (Glasse)
Focal plane M1
M2
M3
M4
M5
Detector
Cold stop
Filters
270 mm
Coronagraphic masks and a slit for low resolution spectroscopy are mounted in the telescope focal plane.
The filter wheel includes the 10 imaging filters, 4 coronagraphic filter/pupil mask combinations and a prism.
STScI, Baltimore, MD02-10 18th May 2006
MIRI Filters for Direct Imaging (Meixner)
m) m) Comment
R 1.2 broad band
R 7.7 2.2 PAH, broad band
R 10 2.0 Silicate, broad band
R 11.3 0.7 PAH, broad band
R 12.8 2.4 Broad band
R 15 3.0 Broad band
R 18 3.0 Silicate, broad band
R 21 5.0 broad band
R 25.5 4.0 broad band
R 25.5 4.0 redundant filter, risk reduction
ND# neutral dens. for coron. acquis.
Test lens N/A N/A testing
Closed blackened blank
N/A for darks
STScI, Baltimore, MD02-11 18th May 2006
Implementation (Boccaletti)
4 masks in focal plane
monochromatic coronagraphs
ND Lyot diaph.+
23 µm filter
/ = 5)
4Q diaph.+
10.65 m filter
/ = 20)
4Q diaph.+
15.5 m filter
/ = 20)
4Q diaph.+
11.4 m filter
/ = 20)
STScI, Baltimore, MD02-12 18th May 2006
Low Resolution Spectrograph, LRS (Meixner)
LRS 5 0.6
• 5-10 m coverage
• R~100 at 7.5 m
•Double prism in filter wheel
STScI, Baltimore, MD02-13 18th May 2006
Medium Resolution Spectrometer - Format (Wright)
10 arcseconds
Channel 1(4.9 - 7.7 m)
Channel 2(7.4 - 11.8 m)
Channel 3(11.4 - 18.2 m)
Channel 4(17.5 - 28.8 m) Wavelength/Velocity
Each channel’s field of view is sliced, dispersed and detected.
REQUIREMENT - Integral Field Spectroscopy with > 3 arcsec field of view from 5 to 28.5 µm.
STScI, Baltimore, MD02-14 18th May 2006
The MRS concept (Wells)
-4
-3
-2
-1
0
1
2
3
4
-4 -2 0 2 4Field of view across slices (arcsec)
IFU 1A
IFU 1B
IFU 2A
IFU 2B
IFU 1B
IFU 1A
IFU 2A
IFU 2B
Collimator
Collimator
Collimator
Collimator
Camera 1
Camera 2
FPA 1
FPA 2
Grating
Grating
Grating
Grating
LW dichroic
centredichroic
SW dichroic
STScI, Baltimore, MD02-15 18th May 2006
MIRI OBA - Medium Resolution Spectrometer (Glasse)
The Spectrometer has two arms, each with its own FPM.
Each spectrometer arm is further divided into 2 channels.
Two mechanisms present gratings and dichroics which cover the full 5 to 28 micron wavelength range by rotation between three positions.
Channel 3
Channel 4
Channel 1
Channel 2
Focal Plane ModuleDichroic/grating wheel
IFU Image Slicer
STScI, Baltimore, MD02-16 18th May 2006
Spectrometer Eng. Qualification Hardware (Glasse)
A dichroic wheel
An image slicing mirror
STScI, Baltimore, MD02-17 18th May 2006
500
1000
1500
2000
2500
3000
3500
4000
4 6 8 10 12 14 16 18 20 22 24 26 28 30
Requirement
Channel 1A
Channel 1B
Channel 1C
Channel 2A
Channel 2B
Channel 2C
Channel 3A
Channel 3B
Channel 3C
Channel 4A
Channel 4B
Channel 4C
MIRI MRS - Spectral Coverage (Glasse)
Wavelength [m]
Sp
ectr
al R
eso
lvin
g P
ow
er
The MRS covers the 5 to 28 micron range in 12 sub-spectra
FRD 2.5.1.
2How the spectra will appear on the MRS’s
two detectors
STScI, Baltimore, MD02-18 18th May 2006
Pretty Hardware Pictures – Ressler
“Front” side of FPM showing
installed detector assembly.
“Back” side showing connector and
thermal strap attachment point.
STScI, Baltimore, MD02-19 18th May 2006
QE, Ressler
Predicted QE With AR-Coatings
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.0 5.0 10.0 15.0 20.0 25.0 30.0Wavelength (µm)
Predicted Response / Photon
FPM-IC
FPM-LW
FPM-SW
Required
TSA Raw
QE exceeds requirement at all wavelengths < 23 microns. MIRI Science
Team has accepted this performance with the understanding that there will
be a reduced sensitivity margin in the 25.5 micron filter.
STScI, Baltimore, MD02-20 18th May 2006
Nearing TRL 6 Completion
“System/subsystem model or prototype demonstration in a relevant environment (ground or space)”
MIRI Sensor Chip Assemblies (SCAs) or representative models must be proven to be at TRL 6
6 key measurements:
QE Dark Current Read Noise Radiation Immunity Vibration Levels Thermal Cycling
STScI, Baltimore, MD02-21 18th May 2006
Detector Readout Scheme (Ressler)
STScI, Baltimore, MD02-22 18th May 2006
Detector Readout Scheme (Meixner)
STScI, Baltimore, MD02-23 18th May 2006
Sensitivity Requirements (Ressler)
Ultimately bounded by the flux of background radiation from the sky and telescope.
[photon s-1 m-1 arcsec-2] JWST Background
Wavelength [micron]5 10 15 20 25
106
105
104
103
Zodiacal Dust
Sunshield
OTA
STScI, Baltimore, MD02-24 18th May 2006
MIRI Team (Meixner)
MIRI Science Team: George Rieke (U of Az/lead)
US: George Rieke (U of Az/lead), Michael Ressler (JPL/Proj. Sci), Margaret Meixner (STScI), Tom Greene (NASA/Ames)
Europe (members rotate): Gillian Wright (UK ATC/co-lead), Torsten Boeker (ESA), Ewine van Dishoeck (Leiden/Netherlands), Christoffel Waelkens (Leuven/Belgium)
MIRI Engineering Leads:
US: Graham Bothwell (JPL/Project Manager); Greg Goodson (JPL/Systems Engineer), Phil Driggers (Goddard/Instrument Manager)
Europe/ESA: Andrea Marini (ESA/PM), John Thatcher (PM/Astrium), Ian Renouf (Systems Engineer)
MIRI Team at STScI:
Margaret Meixner & Scott Friedman MIRI Instrument Scientists Jerry Kriss: JWST/ISIM lead Vicki Balzano & Michael Robinson: MIRI operations and flight
software support
STScI, Baltimore, MD02-25 18th May 2006
MIRI Milestones (Meixner)
MIRI PDR: March 17&18 2005; passed
Detector TRL 6, June 2006
MIRI CDR: September 2006
Cooler TRL 6, January 2007
JWST launch: >2013 FomalhautMIRI Spitzer