NIRSpec Status and PDR Results
Jeff Valenti & Mike Regan
2006 March 16
TIPS/JIM
Light Path
PDR Objectives
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Assess compliance with requirements
Assess NIRSpec system specifications
Assess external interface definitions
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Integrated Science Instrument Module
Microshutter Array
Detector Subsystem
Assess predicted NIRSpec performance
Assess cost, schedule, and risk estimates
PDR Format
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Board
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Technical Panels
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Led by ESA with NASA participation
Co-chaired by NASA Independent Review Office
System
Structure, thermal, and mechanisms
Optics
Electrical and software
Product Assurance
Programmatic Panel
PDR Timeline
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Dec 1 Documents delivered
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Dec 2 Kick-off meeting held
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… Panel meetings …
Jan 6 Panel chairs met
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“Review Item Dispositions” submitted
Jan 31-Feb 2 Co-location
 ESA/Industry
 ESA/Instrument Science Team
Feb 9 Panel chairs reported to board
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Feb 15 Board met
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PDR Verdict
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NIRSpec PASSED its PDR!
PDR Major Findings
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Microshutter technology is a risk
Electrostatic discharge is a risk
Create stray light control plan
Include detector in EMC control plan
Cool light sources used in ground tests
Prevent contamination by water
Manage target acquisition interfaces
Test cold after observatory integration
No Schedule Change
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JWST launch date slipped to June 2013
NIRSpec delivery date is unchanged
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Necessary to control ESA costs
Requires timely definition of interfaces
Requires timely delivery of subsystems
NASA funding ISIM to support schedule
Microshutter Update
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Technology demonstration tests
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Lifetime test: <5% shutters fail after 105 cycles
Acoustic test: <1% shutters fail
Vibration test: <1% shutters fail
Radiation test: <1% shutters fail
Open/closed contrast: >2000
EMC/EMI test
Demonstrate ability to plug shutters in lab
Stiction issue
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0.5% shutter stuck open after 105 cycles
Heating to 300 K causes shutter release
Rogue Path Update
Unbaffled telescope
Sky skirts FSM and
illuminates POM
NIRSpec wants 9 mm
increase in FSM mask
NIRCam coronagraph
blocked by >6 mm
Outer edge of
FSM mask
Inner edge of
NIRSpec mask
Q1 Q2
10
Orders of Magnitude in Scale
Q3 Q4
10
4365171
250K Shutters
10
Plate Scale Changes
We must position
targets in shutters
Allocate 5 mas for
plate scale changes
Corresponds to 0.01%
change in focal length
Rephase primary as
often as once a week