# Presentation: 515532

## JWST Project StatusAAAC, October 12, 2005

**John C. Mather**
**JWST Senior Project Scientist**
**NASA GSFC**

## 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

- <date/time>

- 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

- Galaxy
- assembly

- ?

- ?

## The Epoch of Reionization

- Redshift

- Wavelength

- Wavelength

- Wavelength

**Lyman Forest Absorption**

**Black Gunn-Peterson trough**

**Patchy Absorption**

- z<zi

- z~zi

- z>zi

- .

- Neutral IGM

## JWST Science

- The Eagle Nebula as seen by HST

- 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

## 

- 

- 

- 

- 

**mJy**

**R=2000, 1-******
**100 sec**

**Spectra obtained**
**with the JWST MIRI on the nearest **
**systems can **
**provide detailed **
**insights to the **
**minerals in ring **
**particles and the **
**nature of**
**giant planets**

- Simulated Vega Observation

## Model Picture

## JWST Observatory Architecture

**JWST Observatory Architecture**

**Optical Telescope Element (OTE)**
** **Stable over total field-of-regard
-  Beryllium (Be) optics with GFRP/Boron structure
-  Performance verified on the ground

## JWST Orbit about the Sun-Earth L2 and Launch Configuration

## Ball AMSD II Be Mirror in Optical Test

## Primary Mirror Segment Actuations

**Lightweighted **
**Beryllium Mirror **
**Substrate**

**Actuator for radius **
**of curvature adjustment**

**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.

## Detector Technology Development

-  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**

## NIRSpec: ESA & Astrium

- NIRSpec: 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

## NIRSpec Schematic

## SAT Recommendations and Response

## 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

## 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 Equipment**
**Are in Upper and Lower**
**Pressure Tight Enclosure Inside of Shrouds where**
**Cryo Cycle Needed to Fix Problems**

## JSC “Cup Up” Test Configuration

**Telescope Cup Up**
**Gravity offloaded and**
**On Ambient Isolators **
**Connected to Concrete)**

**Auto-Collimating Flats**
**(isolators above connected**
**to 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**

## 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

## 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**