JWST Project Status AAAC, October 12, 2005

1
JWST Project StatusAAAC, October 12, 2005

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

2
Topics

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

3
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
?
Galaxy assembly
?
Galaxies, stars, planets, life
4
The Epoch of Reionization
Redshift
Neutral IGM
.
zzi
zltzi
zgtzi
Wavelength
Wavelength
Wavelength
Lyman Forest Absorption
Black Gunn-Peterson trough
Patchy Absorption
5
JWST Science

• End of the dark ages first light and
  reionization
• The assembly of galaxies

The Eagle Nebula as seen by HST

• Birth of stars and protoplanetary systems
• Planetary systems and the origins of life

Galaxies in the UDF
6
4
3
2
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
1
R2000, 1-s 100 sec
0
mJy
Simulated Vega Observation
7
Model Picture
8
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

9
JWST Orbit about the Sun-Earth L2 and Launch
Configuration
10
Ball AMSD II Be Mirror in Optical Test
11
Primary Mirror Segment Actuations
Lightweighted Beryllium Mirror Substrate
Observatory optical quality (mid and high
spatial frequency) is manufactured into segments
Actuator for radius of curvature adjustment
12
A NIRCam Imaging Module
A dichroic allows simultaneous observing at two
wavelengths. This modules dual filter wheels
include pupils for wavefront sensing.
13
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

14
NIRSpec ESA Astrium

• gt 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

15
NIRSpec Schematic
16
SAT Recommendations and Response
17
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

18
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
19
JSC Cup Up Test Configuration
Center of Curvature Null and Interferometer
Accessible from top
Auto-Collimating Flats (isolators above
connected to hard points on top of chamber).
Telescope Cup Up Gravity offloaded and On Ambient
Isolators Connected to Concrete)
Focal Plane Interferometer and sources accessible
from below

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

20
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

21
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