UK Space Conference: James Webb Space Telescope (Gillian Wright)

The Successor to Hubble The James Webb Space Telescope

Dr. Gillian Wright, MBE

Science and Technology Facilities CouncilUK-ATC

JWST MIRI European PI

UK Space Conference, Charterhouse School, March 2008

Talk Overview

• Introduction to the JWST Mission and Instruments

• Overview of the JWST MIRI Instrument

• JWST Science

• JWST and MIRI Status


James Webb

• Initiated and secured NASA Astrophysics programme


James Webb Space Telescope

• 6.5m Diameter Primary Mirror

• Infrared Optimised Telescope

• Passively cooled to ~ 40K

• Launch June 2013

• Placed in an L2 orbit

• Mission Lifetime 5-10 years


The JWST Mission• JWST is being built by a

collaboration between NASA, ESA and CSA– Europe has a guaranteed

15% share of the observing time

• It will be the largest space telescope and mission ever launched

• To place such a large telescope in a far away orbit and cool it sufficiently brings unique challenges


Why is JWST an Infrared Telescope ?

To help resolve key outstanding questions about the Universe we now need to:

1. Study further into the early universe than is possible with current telescopes and missions– the ultraviolet and visible light from distant sources is red-shifted into

the infrared part of the spectrum

2. Look deep into regions where stars and planets are forming – Infrared light is less well absorbed by dust and we can see warm dust

directly


JWST Instruments

• JWST is designed to enable broad science investigations by the world-wide astronomical community– Broad- and narrow-band imagery: 0.6–29

μm – Low resolution spectroscopy: 0.6 – 11 μm – Medium resolution integral field

spectroscopy: 5 - 29 μm – Multi-object spectroscopy : 1 – 5 μm and

9.7 sq arc-min FOV– Broad- and narrow band coronagraphic

imagery: 2 – 23 μm

• 4 Instruments provide this capability– Near Infra-Red Camera (NIRCam)– Near Infra-Red Spectrometer (NIRSpec)– Mid-Infra-Red Instrument (MIRI)– Fine Guidance Sensor (FGS)

• The UK has a major role in JWST

NIRCam FGS

NIRSpec MIRI


Stupendous JWST Performance

• JWST offers enormous increase in observational capabilities.– 1,000 x faster than HST in

the near-IR, >10,000 x faster than anything in the mid-IR

• Whenever there is an increase by an order of magnitude or more in observational capability, new discoveries are made

• This gap in performance will never be matched from the ground

The plot shows the relative time gain of JWST compared to a GSMT. 1.0 means an observation with both JWST and GSMT (and Spitzer) will take the same time to reach the same S/N on a point source.( Mountian and Reike 2005)

1 100.01

0.1

1

10

100

1000

10000

100000

Comparative performance of JWST with a 30m GSMT and Spitzer

Tim

e G

ain

(JW

ST /

30m

GSM

T)

Wavelength (microns)

R=5 R=100 R=1,000 R=10,000


MIRI Capability

– Operating wavelength: 5 – 28.5 microns– Field of view: 1.9 x 1.4 arc minutes broad-band imagery w/

coronagraph– R~100 spectroscopy 5 x 0.2 arc sec slit, for 5-10um– R~2000 spectroscopy 3.5 x 3.5 to 7 x 7 arc sec integral field

units

1.3 arcmin

1.7 arcmin


The MIRI Partnership

ESA/ESTEC JWST Project OfficeProdex Office

DSRI Hexapod

PSI Contamination Control Cover

Cryo Harness

INTA MIRI Telescope Simulator (MTS)

CEA ImagerCoronagraph Analysis

LESIA/LAM Coronograph

CSL Input, Optics & Calibration (IOC)Instrument Control Electronics

(ICE)Imager Mirrors

U. of Leuven EGSE Software Support

DIAS Filters

NASA/GSFC JWST Project OfficeSpacecraftISIM

JPL Detector SystemFlight SoftwareCryo-Cooler

MPIA Heidelberg Electrical EngineeringCryo Mechanisms

U. of Köln Low Resolution Spectrometer

Double Prism

ASTRON Spectrometer Main Optics (SMO)

U. Leiden Spectroscopy Analysis

U. of Stockholm Filters and GratingsUK-ATC Principal InvestigatorOptical EngineeringSpectrometer Pre-Optics (SPO)Calibration Sources

Astrium Ltd Project Office & Consortium ManagementPA CoordinationSystem Engineering

U. of Leicester Mechanical EngineeringPrimary StructureMGSE

RAL Thermal Engineering & HardwareAIV Facility and Test/Calibration Lead

STScI Operations U. Arizona DHAS, US PI

The MIRI Partnership was formed because of the enormous science potential of a Mid-IR instrument on JWST


Why is MIRI so challenging ?

Optical System

MIRI FSW

Cooler System

Cooled to 7K, much colder than all the rest of JWST


Key Instrument Design Features

• Lightweighted, all aluminium, homologous, modular optical system

• Supported by thermally isolating carbon fibre hexapod which attaches to ISIM structure.

• Three 1kx1k SiAs detectors.

• 4 Mechanisms – 3 wheels based on ISO design and a contamination control cover

• Light enters from the telescope via the pick-off mirror

• The fields of view of the Imager and the Medium Resolution Integral Field Spectrometer are defined and separated in the IOC

• Imager optics on one side of primary structure, spectrometer on the other

MIRI Imager(incl. Coronagraph &

LRS)

Spectrometer Pre Optics

(SPO)Spectrometer Main Optics

(SMO)

Focal Plane Modules (FPM

Primary Structure

Deck

Input Optics & Calibration

(IOC)

CFRP Hexapod

Spectrometer Main Optics

(SMO)



Interface Connector

Panels(ICP x 3)


JWST Science : Where are the 1st Stars and Galaxies ?

• The host galaxies of luminous quasars at redshifts >6, and the first light objects will both be found in deep near-IR images

• Adding MIRI data for sources found in NIRCam surveys will provide a unique diagnostic for identifying first light sources and reddened ultraluminous galaxies forming quasars

100000

1000000

0 1

Wavelength (microns)

Flux

(nJy

)

first lightolder galaxyquasarfrst lght, filtersolder, filtersquasar, filters

3

30

1 10 5 2

10


JWST Science:How do galaxies evolve ?

• There is a population of very luminous galaxies that are invisible in the Hubble Deep field because they are so dusty

• SCUBA (1996-) surveys confirmed by ISO (1999) and Spitzer (now) surveys have discovered a population of obscured high-redshiftgalaxies that are very luminous

• Mid-IR spectroscopy of these sources will map the history of dust enshrouded star formation in the universe SCUBA and ISOCAM images of HDF


JWST Science :How do Planets Form ?


JWST Science:Planets and Debris disks - the example of Vega

Model

Spitzer (70um)The JWST MIRI View at 24um ?Pictures: Holland, Wyatt, Su, Rieke

• MIRI studies of debris disks will complement and add to work with other new space and ground based instruments the UK is developing.

• MIRI has unique ability to study structure of disks and chemistry of the material

• Warm dust (zodiacal light) ≥ 1% of disks are now known from Spitzer surveys to have warm dust component

SCUBA image (850um) Resonant model

Planet


JWST Science: Our Solar System

• The Kuiper Belt is a relic of the young Solar System– clues to the dynamical and

chemical properties of the early Solar System.

• JWST will have the capability to obtain R=100 spectra of all known KBOs.– water ice, hydrocarbons,

hydration bands, CO, N2, CH4

• 20 and 25 um photometry of all known KBOs.– albedos, and hence radii.

• Main Belt Comets orbit entirely within the asteroid belt– Asteroid belt is possible

source of Earth’s water after end of planet-building phase

• Main belt comets could be the remnant of that water reservoir

• JWST is currently the only planned observatory able to characterize water content of MBCs.


Where are we ?

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019

Concept Development Design, Fabrication, Assembly and Test

FormulationAuthorization

NOW Launch

science operations ...

ICR[i.e., PNAR]

…

MIRI Delivery


Telescope mirrors are one of the key components

17 flight primary mirrors are now in various stages of

grinding/polishing


Sunshade Membrane Testing


Where is MIRI ?The MIRI Verification Model

Spectrometer Pre-Optics, UK-ATC Spectrometer Main Optics, Netherlands

Focal Plane Module, JPLImager, France

Filters, Ireland & Sweden Mechanism Germany

Calibration Source, UK-ATC


Integrated MIRI Verification Modelin Test, RAL, October 2007

● Alignment, gravity release and image quality measurements all indicate that the optical performance is within specifications


MIRI Now• VM cryogenic testing at

7K at RAL

• Flight Model Construction • ALL the flight arrays have just

been selected by MIRI Science Team

FM Structure, U. Leicester


First Light (ground test) Images

Image of pinhole, scale stretched to show diffraction Spectra


Conclusions

• JWST is on schedule for a mid-2013 Launch– All 10 enabling technologies have

been proven in the lab under flight-like conditions

– All instruments undergo integrated tests in 2008. MIRI is 1st to achieve this milestone

• JWST will dominate astronomy as Hubble has done due to its unique capabilities– MIRI will lead to significant and major

discoveries

UK Space Conference: James Webb Space Telescope (Gillian Wright)

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