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JWST Project StatusAAAC, October 12, 2005

John C. MatherJWST Senior Project Scientist

NASA GSFC

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Topics

• Science summary• Mission summary• Technology status• Test plan status• Contamination and Stray Light plan

Top JWST Goal - Find the First Light after the Big

Bang• How and from what were galaxies

assembled?

• What is the history of star birth, heavy element production, and the enrichment of the intergalactic material?

• How were giant black holes created and what is their role in the universe?

• Three instruments to do this: NIRCam (NASA/CSA), NIRSpec (ESA), MIRI (ESA/consortium/NASA), plus FGS-TF (CSA)

as seen by COBE

Galaxies,stars,planets,life

Galaxyassembly

?

?

4SWG Meeting, STScI, September 24 2002

JWJWThe Epoch of Reionization

Redshift

Wavelength Wavelength Wavelength

Lyman Forest Absorption

Black Gunn-Peterson trough

Patchy Absorption

z<zi

z~zi

z>zi

.

Neutral IGM

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National Aeronautics and Space AdministrationGoddard Space Flight Center JWST Science

The Eagle Nebula as seen by HST

The Eagle Nebulaas seen in the infrared

• Birth of stars and protoplanetary systems

• Planetary systems and the origins of life

Galaxies in the UDF

• End of the dark ages: first light and reionization

• The assembly of galaxies

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National Aeronautics and Space AdministrationGoddard Space Flight Center

-sec

mJy

R=2000, 1-100 sec

Spectra obtainedwith the JWST MIRI on the nearest systems can provide detailed insights to the minerals in ring particles and the nature ofgiant planets

Simulated Vega Observation

National Aeronautics and Space AdministrationGoddard Space Flight Center

Model Picture

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JWST Observatory Architecture

Secondary Mirror (SM)• Deployable tripod

for stiffness• 6 DOF to assure

telescope alignment

Optical Telescope Element (OTE)• Stable over total field-of-regard• Beryllium (Be) optics with GFRP/Boron structure

• Performance verified on the ground

Primary Mirror (PM)• 18 (1.315 m) hex segments• Simple semi-rigid WFS&C for phasing

• 6 degree of freedom rigid body• Radius corrections

•Deployable chord fold for thermal uniformity

Tower• Isolates telescope from

spacecraft dynamic noise

ISIM • NIRCam, NIRSpec, MIRI & FGS• Enclosure for FPE• Simple Kinematic interface

Sunshield• Passive cool ISIM/OTE to ~40K• Limits momentum buildup

Spacecraft Bus• Isolates reaction wheel noise

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JWST Orbit about the Sun-Earth L2 and Launch Configuration

(T0) Launch (L + 63 days) Cool

down near steady state; Repeat WFS&C Commissioning

(L + 28 days) Initial WFS&C Commissioning

(L+ 41 min) Solar Array Deployment

(L + 14 hr) High Gain Antenna Deployment

(L + 6 months) Commissioning Complete

(L + 113 days) Initiate Observatory Commissioning

(L + 4 days) OTE Deployment

(L + 2 days) Sunshield Deployment

1 weekinterval

Stowed Observatory in 5meter shroud

(T0) Launch (L + 63 days) Cool

down near steady state; Repeat WFS&C Commissioning

(L + 28 days) Initial WFS&C Commissioning

(L+ 41 min) Solar Array Deployment

(L + 14 hr) High Gain Antenna Deployment

(L + 6 months) Commissioning Complete

(L + 113 days) Initiate Observatory Commissioning

(L + 4 days) OTE Deployment

(L + 2 days) Sunshield Deployment

1 weekinterval1 weekinterval

Stowed Observatory in 5meter shroud

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National Aeronautics and Space AdministrationGoddard Space Flight CenterBall AMSD II Be Mirror in

Optical Test

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Primary Mirror Segment Actuations

Lightweighted Beryllium Mirror Substrate

Actuator for radius of curvature adjustment

Actuators for 6 degrees of freedom rigid body motion, independent of ROC control

Actuator development unit

Observatory optical quality (mid and high spatial frequency) is manufactured into segments

A NIRCam Imaging Module

A dichroic allows simultaneous observing at two wavelengths.

This module’s dual filter wheels include pupils for wavefront sensing.

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National Aeronautics and Space AdministrationGoddard Space Flight CenterDetector Technology Development

NICMOS 256x256

HgCdTe

WFC3 1024x1024 JWST Proto-type 4Kx4K

NICMOS and IRAC arrays have demonstrated the basic detector architecture but with lower performance and smaller formats.

TRL 4 achieved Feb 2002 with JWST performance levels achieved

TRL 5 achieved Feb 2003 with JWST size 2Kx2K devices, mosaicing

Astronomical Image with prototype, Sept. 2003

Flight detectors being manufactured

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National Aeronautics and Space AdministrationGoddard Space Flight CenterNIRSpec: ESA & Astrium

• > 100 Objects Simultaneously• 9 square arcminute FOV

• Implementation:– 3.5’ Large FOV Imaging Spectrograph– 4 x 175 x 384 element Micro-Shutter Array– 2 x 2k x 2k Detector Array– Fixed slits and IFU for backup, contrast– SiC optical bench & optics

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NIRSpec Schematic

Fore optics CollimatorCamera

Micro-Shutter Array Grating/Prism

WheelDetector

ArrayFilter

Wheel

Pick-offOptics

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SAT Recommendations and Response

SAT Recommendation Action Recommended Planned Action(s)

ProCompletion Date

1. Prioritize 1.7-28um Imaging and Spectroscopy

Eliminate low priority modes if they reduce risk and future cost

Planning to eliminate 1.1 micron sensitivity requirement at MRD level. 1 Tunable Filter module in FGS will be eliminated and FGS mass allocation reduced by 80Kg.

Pam SuRTC's by 12/05

2. "Cup Up" testing Pursue planning for "Cup Up" testing and any other I+T savings

"Cup Up" cryo approach has been made the baseline although additional work is needed to fully demonstrate feasibility. A separate trade study is also under way to see if the optical test configuration can be simplified.

Lee FeRTC's by 12/05

3. Eliminate 1um Encircled Energy and modify stability requirement to every 2% photometric accuracy at 2um.

Delete L.1 1um EE Requirement, Rewrite EE Stability

Updated plan is to eliminate the 1um Encircled Energy Requirement altogether. Working with prime contractor on redefinition of stability spec at 2um which could be accompanied by a Field of Regard reduction to keep it cost neutral.

Lee FeiRTC's by 12/05

4. Relaxation of Scattered Light Requirements

Relax particulate requirements to L. 720 (PM) and 630 (SM) - note: need to confirm the eventual relaxation is made consistent with the sensitivity relaxation recommended by the SAT

Team will consider particulate impacts from the Cup Up trade, SSDIF I+T trade, Ariane assessment and will recommend a reduction to the sensitivity and stray light relaxation commensurate with that needed. Will consider particle size distribution and cleaning.

Matt GreRTC's by 4/06

5. Stability Perform Updates Every 7-10 days.

Project is evaluating best approach to mitigating stability risk (see presentation). Updating every 7-10 days will be implemented if appropriate. Recent creep data suggests that structural stability will not require this relaxation. Thermal

Mark RTC's by 12/05

6. AnisotropySignificant relaxation and possible elimination Current plan is to eliminate this requirement altogether.

Lee RTC's by 12/05

7. Mission Life Keep 10 year goal if at all possible No changes to current plan.

Mikdone

Note: Plan is to submit RTC's for requirement changes in December, 2005

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Technology Status

• All technologies to be ready for by Non-Advocate Review (NAR)

• Key technologies:– Mirrors - flight mirror blanks made and being

machined; EDU being polished; operator error (due to an unexpected feature in the machine) at Axsys drilled hole in one blank, no effect on schedule

– Detectors - TRL 5 achieved in 2003, all performance specifications met; some HgCdTe detectors disintegrated, apparently due to insufficient cleaning prior to bonding to BCS (Balanced Composite Substrate); new recipe verified by repeated thermal cycles

– Microshutters - GSFC - recipe found for keeping shutters flat at room temperature and cold; on track with all needed tests

– ASICs - all performance specifications met; final foundry run starting with revised masks

– Cryocooler - will select contractor in January

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Baseline “Cup Down” Tower Configuration at JSC (Before)

Most recent Tower Design shows an Inner Optical Tower supported by a Outer structure with Vibration Isolation at the midplane. Everything shown is in the 20K region (helium connections, etc. not shown) except clean room and lift fixture.

Plan called for 33KW He cooldown capability, 12 KW steady state, major challenges for JSC

JSC currently has 7 KW He capability

Plan required 10 trucks of LN2/day during cooldown

Large Risk on Cooldown Time Assumptions

Clean room

Clean room

Interferometers, Sources,Null Lens and Alignment EquipmentAre in Upper and LowerPressure Tight Enclosure Inside of Shrouds whereCryo Cycle Needed to Fix Problems

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Telescope Cup UpGravity offloaded andOn Ambient Isolators Connected to Concrete)

Auto-Collimating Flats(isolators above connectedto hard points on top of chamber).

Center of Curvature Null and Interferometer Accessible from top

Focal Plane Interferometer and sources accessible from below

JSC “Cup Up” Test Configuration

•Isolators moved outside of shroud/vacuum•Telescope comes in deployed on tracks with minimal time in chamber before pump down

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Contamination Plan

• “Cup Up” test at JSC is not a major contaminant source

• Launch effects are major driver– Ariane meeting planned for this fall– Particle generation by sunshield rubbing during launch?

• We will be able to clean mirrors• Need independent review of all models, assumptions,

methods• Detail required: cleaned mirrors have different

particle size distributions and different BRDF shapes than before cleaning

• Goal is twofold:– Cost-effective particulate contamination plan– Consistency with SAT assumptions regarding sensitivity losses

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Summary

• All review committees endorse JWST plans• Scientific descope recommended by SAT accepted

and being implemented• Cost control and risk reduction approach

endorsed by SAT and IPAO reviews• Replan in progress for new launch date and

budget• Technology progress excellent, will be ready

for NAR