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NIRSpec Status and PDR Results
Jeff Valenti & Mike Regan
2006 March 16
TIPS/JIM
Light Path
PDR Objectives
Assess compliance with requirements Assess NIRSpec system specifications Assess external interface definitions
Integrated Science Instrument Module Microshutter Array Detector Subsystem
Assess predicted NIRSpec performance Assess cost, schedule, and risk estimates
PDR Format
Board Led by ESA with NASA participation Co-chaired by NASA Independent Review Office
Technical Panels System Structure, thermal, and mechanisms Optics Electrical and software Product Assurance
Programmatic Panel
PDR Timeline
Dec 1 Documents delivered Dec 2 Kick-off meeting held … Panel meetings … Jan 6 Panel chairs met
“Review Item Dispositions” submitted Jan 31-Feb 2 Co-location
ESA/Industry ESA/Instrument Science Team
Feb 9 Panel chairs reported to board Feb 15 Board met
PDR Verdict
NIRSpec PASSED its PDR!
PDR Major Findings
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
JWST launch date slipped to June 2013 NIRSpec delivery date is unchanged
Necessary to control ESA costs Requires timely definition of interfaces Requires timely delivery of subsystems NASA funding ISIM to support schedule
Microshutter Update
Technology demonstration tests 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 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
Orders of Magnitude in Scale
10 10
10
4365171250K Shutters
Q1 Q2
Q3 Q4
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