Andrew Bunker (Oxford University, JWST-NIRSpec Instrument Team)
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Transcript of Andrew Bunker (Oxford University, JWST-NIRSpec Instrument Team)
Andy Bunker, Megastructures Meeting, May 2010
Andrew Bunker (Oxford University,JWST-NIRSpec Instrument Team)
The James Webb Space Telescope:Our Megastructure in Outer Space
Andy Bunker, Megastructures Meeting, May 2010
NGST/JWST History• Coordinated NASA, ESA and CSA Studies
since 1997• JWST is consistent with the scientific
program for a “Large Infrared-Optimized Space Telescope”, described in the report “HST and Beyond” (Dressler 1996), and
• the program for the “Next Generation Space Telescope”, which was given top priority by the National Academy of Sciences survey “Astronomy and Astrophysics in the New Millennium” (McKee & Taylor, 2001).
Andy Bunker, Megastructures Meeting, May 2010
NGST/JWST History
1996: ESA invited to participate in NGST studies, 8-m
1998: 2nd NGST Conference held in LiegeAd Hoc Science Working Group (ASWG)
1999: Design Reference Mission completed
2001: ESA NIRSpec and MIRI Studies initiated
2002: NGST renamed JWST, Ariane V Launcher
2003: Telescope reduced to 6.5-m
2005: “Tiger team” re-scope: PSF at 1micron not science driver
2007: Technology Ready
2008: Start of phase C/D (construction)
2014: Launch (Cycle 1 observations begin 2015)
Andy Bunker, Megastructures Meeting, May 2010
Who Was James Webb?
James E. Webb Second NASA administrator, during ApolloEdwin Hubble
Andy Bunker, Megastructures Meeting, May 2010
What is JWST?
• 6.55 m deployable primary
• Diffraction-limited at 2 µm
• Wavelength range 0.6-28 µm
• Passively cooled to <50 K
• Zodiacal-limited below 10 µm
• Sun-Earth L2 orbit
• 4 instruments• 0.6-5 µm wide field camera (NIRCam)• 1-5 µm multiobject spectrometer (NIRSpec)• 5-28 µm camera/spectrometer (MIRI)• 0.8-5 µm guider camera (FGS/TF)
• 5 year lifetime, 10-11 year goal
• 2014 launch
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Andy Bunker, Megastructures Meeting, May 2010
Goddard Space Flight CentreNorthrop GrummanOperations:STScIProject Scientist: John Mather
Andy Bunker, Megastructures Meeting, May 2010
JWST Architecture
Optical Telescope
Element (OTE)
Integrated Science Instrument
Module (ISIM) Element
Spacecraft Bus
Sunshield
Sun
Andy Bunker, Megastructures Meeting, May 2010
ESA Contributions to JWST
• NIRSpec• ESA Provided• Detector & MEMS Arrays from NASA
• MIRI Optics Module• ESA Member State Consortium• Detector & Cooler/Cryostat from NASA
• Ariane V Launcher (ECA)
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(closely similar to HST model…)
Andy Bunker, Megastructures Meeting, May 2010
Telescope
Andy Bunker, Megastructures Meeting, May 2010
Funky PSF?
Image Core
PSF Wings
2 µm
Andy Bunker, Megastructures Meeting, May 2010
Andy Bunker, Megastructures Meeting, May 2010
0
Orbit
~1,500,000 km
~374,000 km
Trajectory correction
maneuver 1 L + 15 hrs
Trajectory correction
maneuver 2 (if required) L + 25 days
L2 orbit achieved
L + 109 days Launch
Telescope deployment
L + 4 days
Observatory first light (ISIM at safe
operating temp) L + 59 days
Initiate ISIM testing and certification
L + 113 days
Sunshield deployment
L + 2 days
Observatory available for
ISIM activities
L + 70 days
L2
Main EngineStart 1264 sec
Main EngineCut-Off 1785 sec
Main EngineStart 21694 sec
Main EngineCut-Off 22084 sec
JWSTseparation39 min
Andy Bunker, Megastructures Meeting, May 2010
Sky "glow" in the near-IRSky "glow" in the near-IR
Andy Bunker, Megastructures Meeting, May 2010
MIRI - mid-infrared instrument 5 < λ < 27 μm
Cryocooler to 7K; Broad-band imaging; 2sq arcmin
R=3000 spectroscopy; also has a coronograph
European Consortium, ESA & JPL (50/50).
Andy Bunker, Megastructures Meeting, May 2010
NIRCAM : 1-5micron imager (U of Arizona)
10 square arcmin, two channels at once
Uses Hawaii-2KRG arrays
FGS-TFI (Fine Guidance Sensor & Tunable Filter Imager), Canadian Space Agency
Can take 1% narrow-band images over 1.6-4.9microns, 5 square arcmin
Andy Bunker, Megastructures Meeting, May 2010
JWST Imaging Sensitivity
1 10Wavelength (µm)
Sunshield Scatter> 10 µm
PSF Grows
Mid-IR DetectorDark Current
Gold Coatings< 0.6 µm
105 s, R ~ 3, S/N=10
11 nJy ~AB = 31.4
Andy Bunker, Megastructures Meeting, May 2010
NIRSpec
• 3 x 3 arcmin FOV
• 1-5 µm coverage
• R~1000, R~100 multiplexed
• >100 sources simultaneously
• Configurable slit width/length
• MEMS array - “build your own slitmask in space”
Andy Bunker, Megastructures Meeting, May 2010
Slide from J. Gardner (NASA)
Andy Bunker, Megastructures Meeting, May 2010
1. The End of the Dark Ages: First Light and Reionization
2. The Assembly of Galaxies
3. The Birth of Stars and Protoplanetary Systems
4. Planetary Systems and the Origins of Life
…scientific objectives and requirements of the James Webb Space Telescope (JWST)
Project. JWST will be a large, cold, infrared-optimized space telescope
designed to enable fundamental breakthroughs in our understanding of
the formation and evolution of galaxies, stars, and planetary systems.
Andy Bunker, Megastructures Meeting, May 2010
Detector Array• 2K4K FPA comprised of two 2K2K
sensor chip assemblies (SCAs)
• =0.6–5.0 µm HgCdTe detectors (Rockwell)
• FPA passively cooled to T=34–37 K
• Key Performance Parameters:• Total noise =6 electrons rms per t=1000 seconds exposure)• QE = >80%
• NIRSpec is detector background limited in nearly all
modes (!)
• Non-stop (“up the ramp”) read and telemetry• 12 s frame time, 1 frame downlink each 50 s
Andy Bunker, Megastructures Meeting, May 2010
The European JWST FamilyNIRSpec: Arribas, Santiago (Madrid)
Bunker, Andrew (Oxford)Charlot, Stephane (IAP)Franx, Marijn (Leiden)Jakobsen, Peter (ESA) - ChairMaiolino, Roberto (Rome)Moseley, Harvey (NASA/GSFC)Rauscher, Bernie (NASA/GSFC)Regan, Mike (STScI)Rix, Hans-Walter (MPIA)Willott, Chris; Crampton, David (HIA)
SWG: Lilly, Simon (ETH)McCaugrean, Mark (ESA)Wright, Gillian (Edinburgh)
MIRI: co-PI: G. WrightWith a large team (Too many to list here…)
Andy Bunker, Megastructures Meeting, May 2010
NIRSpec IST
Andy Bunker, Megastructures Meeting, May 2010
Physical Layout
Andy Bunker, Megastructures Meeting, May 2010
Micro Shutter Array
Active MSA Area3.6’3.4’Mounting FrameDetector ArrayFixed Slits and
IFU Aperture
Direction of Dispersion
4 x 384 x 185 Shutters 9 Square Arcmin of MSA
Area
Single 200 mas x 450 mas slitssurrounded by 50 mas wide bars
>100 objects simultaneously
Andy Bunker, Megastructures Meeting, May 2010
Andy Bunker, Megastructures Meeting, May 2010
MSA Contrast Simulation
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HDF-S Field
Select Objects(Detail)
Andy Bunker, Megastructures Meeting, May 2010
MSA Contrast Simulation
QuickTime™ and aQuickDraw decompressor
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Undispersed image with MSA mask in place
Spoilers!
Configure Slits(Detail)
Andy Bunker, Megastructures Meeting, May 2010
MSA Contrast Simulation
QuickTime™ and aQuickDraw decompressor
are needed to see this picture.
Configure Slits(larger view)
Image Mode with MEMS mask in place
Andy Bunker, Megastructures Meeting, May 2010
MSA Contrast Simulation
QuickTime™ and aQuickDraw decompressor
are needed to see this picture.
Insert Grating and Integrate
Andy Bunker, Megastructures Meeting, May 2010
Why are we bothering?
Want to find the sources which reionized the Universe, and chart
the history of galaxy (mass) assembly & star formation
Lyman-alpha (if it emerges at all pre-Gunn Peterson)
then it will be a good way to find galaxies, but the flux does not
tell us the star formation rate (but EW might provide clues to the
IMF). Pop III???
Looking at longer wavelengths for other diagnositc lines (also get
reddening, metallicity)
Couple with NIRCAM SEDs
Brightest sources: some hope of velocity dispersions
Want overall luminosity functions, EW distributions