Download Summary of the JWST Mission and Observatory Systems Requirements Reviews, and

Summary of the JWST Mission and Observatory Systems Requirements Reviews, and Micro-Shutter Array (MSA) Confirmation Review

Jerry Kriss

01/15/2004

TIPS/JIM

SRR Objectives  Confirm that mission-level and observatory requirements meet the project objectives  Confirm observatory-level specifications are sufficient to meet the project objectives  Validate that the mission architecture concept can support the functional, operational, interface and performance requirements  Show that the requirements have been flowed down and are understood at the next level. 01/15/2004

TIPS/JIM

SRR Review Team Dennis Dillman, Chair Steve Graham Alain Berinstain Ted Harper Jacques Louet Colin Jones Steve Scott Alexander Krimchansky Gene Waluschka Sachi Babu Tom McCarthy Mark Fontaine Joe Schepis Peiman Maghami Minh Phan Dr. Mal Niedner

01/15/2004

GSFC System Review Office GSFC Project Management CSA CSA ESA ESA GSFC Chief Engineer GSFC GSFC Optics GSFC Detectors GSFC Thermal GSFC GSFC Electromechanical GSFC GSFC GSFC Space Sciences

TIPS/JIM

JWST Requirements Tree JWST Program Plan JWST-PLAN-000633 L1

Program

Baselined In CM Review Drafts Available Allocation Documents

System FGS SRD

JWST Science Requirements Document JWST-RQMT-002558SR

NIRCam SRD NIRSpec SRD

JWST Mission Requirements JWST-RQMT-000634 MR

JWST Performance Assurance Requirements JWST-RQMT-000650 PA

JWST Mission Operations Concept Document JWST-OPS-002018 MOC FGS OCD

MIRI SRD Budgets WFE Rev Q 03-JWST-0405 Efficiency Pointing

WFS&C Requirements Allocation Document JWST-RQMT-002017 WFS

NIRCam OCD

EMC Control Plan JWST-PLAN-002449

NIRSpec OCD

EMC

Performance Quality Assurance Plan JWST-PLAN-002412

Contamination Control Plan JWST-PLAN-002028

CCP

PQ

MIRI OCD

Segment Flight Observatory to Ground Segment IRD JWST-IRD-000696 FG

Ground Segment Requirements JWST-RQMT-001056

GS

JWST Observatory Specification JWST-SPEC-002020

RD

Launch Segment Specification JWST-SPEC-001999

OL

OBS

JWST-ICD-001998 FGC

Radiation Requirements Allocation Specification JWST-SPEC-000871

Observatory to Launch Segment IRD JWST-IRD-002000

JWST System Verification Plan JWST-PLAN-002027

LS

JWST-ICD-002001

OLC

Environmental Req’s for the JWST Observatory JWST-SPEC-003149 EV

Observatory I&T Plan JWST-PLAN-002030 Observatory to GSE IRD D36127 OG D36128 OGC

Fault Protection Requirements Document JWST-RQMT-002450

FP

Element ISIM Requirements Document JWST-RQMT-000835

ISIM

ISIM to OTE and Spacecraft IRD JWST-IRD-000640 ISIM to OTE and IOS-IR JWST-ICD-001831

01/15/2004

SC Requirements Document JWST-RQMT-002039

SC

IOSC

TIPS/JIM

Spacecraft to OTE ICD D35231 SOIC

OTE Specification JWST-RQMT-002021

OTE

JWST Science Requirements (John Mather presenting)  Four themes: • • • •

First Light Assembly of Galaxies Birth of Star and Planetary Systems Planetary Systems and the Origins of Life

 Level 1 Mission Success Criteria: • • • • • • • •

Density of galaxies Spectra of galaxies Physical and Chemical properties of young stellar objects Observing time---5 yr mission, 1.1e9 s on target Telescope > 25 m2 Strehl ratio > 0.8 at 2 m Encircled energy > 0.74 within 0.15 arc sec at 1 m, stable for > 24 hrs. Thermal environment zodi limited 0.6 -- 10 m

 Example of how Level 1 requirements flow down: 1st-light objects are rare ( large, unvignetted FOV with low distortion. 01/15/2004

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Requirement Changes Since the Delta-MDR  Redesigned sun shield---smaller, better clearances, simpler deployment – but, it could make mission planning more difficult.  Upgrade the power system to accommodate ISIM power needs.

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TIPS/JIM

Requirements Still in Work  Moving targets. Quantitative requirements are TBD, depending on cost.  Sensitivity. New numbers developed, but CCB on hold pending NGST replan contract change.  Mass allocations are TBD pending resolution of the ISIM Electronics Compartment (IEC) study.  Ariane 5 change not yet flowed down (no expected impact).  FOV offsets not yet flowed done (no expected impact).  Reliability. Recent MRD change says goal is 92% for Spacecraft+OTE. Goal for whole observatory is pending.  OTE to ISIM structural interface definition.  X vs. Ka-band study. [Should finish soon in favor of Ka.] 01/15/2004

TIPS/JIM

Key Issues  Concept for locating ISIM electronics in Region 2 is not viable. • FPEs must be within 6m of focal planes, in Region 2 • Adding ICE boxes advantageous • "Saddle-bag" configuration won't work. (Too massive; thermal problems.) Further work underway. (IEC trade study. Will take FPE rqmnts into account.)

 Mass Allocations • Current mass reserves are at 21%. Would like to be at 25%. Biggest problem areas are the IEC accommodation, and the sun shield containment system. • Spacecraft is 250 kg over its allocation • OTE is 405 kg over its allocation • MIRI dewar is 20 kg over its allocation; NIRCam is 7 kg too heavy. 01/15/2004

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(ISIM Region 1)

(ISIM Region 2)

(ISIM Region 3)

01/15/2004

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SRR Summary Results  The board thought that the review was excellent.  ~60 Requests for Action (RFAs) generated.  Major issues in the RFAs: • Request for an Observatory-level TV test. • Request for deployment tests in TV. • Desire to make several of the Mission/Obs rqmnts less vague and more verifiable (e.g., those related to eventdrive ops). • Need to do a better flow down of the efficiency rqmnt and tie it in to data quality and reliability in a more comprehensive way. • Fault handling requires more development. 01/15/2004

TIPS/JIM

Micro-Shutter Array (MSA) Confirmation Review  Held 12/18/03 at GSFC to assess whether the MEMS microshutter array should be the slit-defining mechanism for NIRSpec.  Successes: • Fabricated 128 x 64 arrays (flight will be 384 x 175) • Demonstrated 2-D addressing • Implemented light shields • Performed cryogenic life tests • Measured pixel failure rate at end-of-life • Measured open/closed shutter contrast ratio [2,00010,000 warm; ~200 cold (due to shutter curvature)] • Performed an acoustic test 01/15/2004

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100 m

20 m

01/15/2004

Magnetic Stripes on MSA Frontside

MSA Light Shields

100 m

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MSA Backside

Micro-Shutter Array (MSA) Confirmation Review  Concerns: • • • •

Yield is still low Light shields frequently break off Shutters curve and bend when cooled Life testing does not meet