Mid-InfraRed Instrument (MIRI) Delta-Systems Requirements Review: March 9

1. Mid-InfraRed Instrument (MIRI) Delta-Systems Requirements Review: March 9 Margaret Meixner MIRI support scientist

2. Result of MIRI delta-SRR MIRI project successfully completed the delta System Requirements Review. The review board was very complementary of the extensive preparation of the requirements documentation and the systematic documentation of the flow down of the requirements. The hard work of the entire MIRI Team was acknowledged and commended.

3. MIRI has four Science Modes 1. Photometric Imaging 3. Coronagraphy 2. Low Resolution Spectroscopy

4. MIRI has four Science Modes 4. Integral Field Unit Spectroscopy

5. S/C CTP IC&DH FPE Thermal Switch Temperature Transducer Valve Actuator S ICE T V MIRI in the System REGION 1(37 K) REGION 2 (75-300 K) REGION 3 (300 K) Launch-CriticalDiscretes /Passive Analog Dewar I/Fs Under review Routine Monitoring Discretes / Passive Analog T V T MIRI FSW(TBD) DCE RS-422 / 1553B (TBD) T S T Thermal Straps MIRI Dewar(6.65 K @ FPM Strap I/F 6.85K @ OBA Strap I/F) SpaceWire 1553B MIRI FSW MIRI OBA (7 K)

6. System Requirement Review • Held on Nov 4 and 5, 2003 at JPL • First Instrument SRR on JWST. The higher level flow downs were not complete • Was held before ISIM and Observatory SRRs • Board requested delta SRR to address issues raised in the board report • Received 97 RFAs

7. After MIRI SRR • 45 RFAs were reassigned internally • NIRCam successfully completed their SRR • MIRI prepared plan for addressing the Board comments • Observatory Successfully completed their SRR • ISIM SRR scheduled for March 16 • MIRI delta SRR scheduled for March 9 • Established the content and the format for delta SRR in consultation with the review board • Delta SRR package distributed on Feb 24

8. Review Board Report Summary – Part I • The working relationships between the MIRI principals, JPL and ESA, appear to be excellent • The science requirements in particular appear to be clearly understood • The MIRI team provided a clear depiction of open issues affecting the instrument system. • It was observed that the MIRI team, which is spread over the globe with multiple centers and institutional participants, is obviously fully operational and is filled with an enthusiastic spirit. • The MIRI team has a clear definition of the instrument design at this early stage of the project. • The MIRI project has an excellent, very capable team. • There appears to be an excellent understanding and flowdown of the science requirements. There was clearly a thorough knowledge of the source of the science requirements and how the requirements flowdown to the subsystems.

9. Board Report Summary – Part II Group a) 1,3,4,5,9 and 11 • The flow down from the SciRD to the instrument system and subsystem architecture was spotty • Few presenters discussed the derived, flow down of the requirements, instead they presented designs that reflected their approach to meeting the assumed requirements. • Consistency of the OBA design approach with the requirements was not made clear to the Board. • Uncertainties plague the definition of the requirements. The JWST project made changes in its requirements documentation, the System IRD, which was not available to the MIRI team in time to be incorporated in the material presented at the MIRI SRR. This situation impacted the ability of the MIRI Team to convince the Board that it had a clear grasp of the requirements and the impact of the requirements on the system design.

10. JWST Program Plan JWST-PLAN-000633 L1 Program System JWST Performance Assurance Requirements JWST-RQMT-000650 JWST Science Requirements Document JWST-RQMT-002558 JWST Mission Requirements JWST-RQMT-000634 JWST Mission Operations Concept Document JWST-OPS-002018 SR MR MOC PA FGS OCD WFS&C Requirements Allocation Document JWST-RQMT-002017 Contamination Control Plan JWST-PLAN-002028 Performance Quality Assurance Plan JWST-PLAN-002412 EMC Control Plan JWST-PLAN-002449 NIRCam OCD Budgets WFE Rev Q 03-JWST-0405 Efficiency Pointing NIRSpec OCD WFS EMC CCP PQ MIRI OCD Segment JWST Observatory Specification JWST-SPEC-002020 Ground Segment Requirements JWST-RQMT-001056 Flight Observatory to Ground Segment IRD JWST-IRD-000696 Observatory to Launch Segment IRD JWST-IRD-002000 JWST System Verification Plan JWST-PLAN-002027 JWST-ICD-001998 FG JWST-ICD-002001 OL GS OBS FGC OLC Environmental Req’s for the JWST Observatory JWST-SPEC-003149 Radiation Requirements Allocation Specification JWST-SPEC-000871 Observatory I&T Plan JWST-PLAN-002030 EV RD Fault Protection Requirements Document JWST-RQMT-002450 Observatory to GSE IRD D36127 D36128 OG FP OGC Element ISIM Requirements Document JWST-RQMT-000835 ISIM to OTE and Spacecraft IRD JWST-IRD-000640 OTE Specification JWST-RQMT-002021 Spacecraft to OTE ICD D35231 SC Requirements Document JWST-RQMT-002039 SOIC OTE SC IOS-IR ISIM ISIM to OTE and JWST-ICD-001831 IOSC Observatory Requirements

11. JWST Observatory Specification JWST-SPEC-002020 Fault Protection Requirements Document JWST-RQMT-002450 OBS FP Segment Element Mission Assurance Requirements For the JWST Instruments JWST-RQMT-002363 ISIM to OTE and Spacecraft IRD JWST-IRD-000640 ISIM Requirements Document JWST-RQMT-000835 MAR ESA JWST Product Assurance Requirements Document ESA-JWST-RQ-64 IOS-IR ISIM to OTE and JWST-ICD-001831 ISIM IOSC PAR CSA Performance Assurance Requirements CSA-TBD NIRCam IRD JWST-IRD-000780 NIRSpec IRD JWST-IRD-000781 MIRI IRD JWST-IRD-000782 FGS IRD JWST-IRD-000783 INCU INSU IMU IF ISIM to OTE and JWST-ICD-000728 ISIM to OTE and JWST-ICD-000729 ISIM to OTE and JWST-ICD-000730 ISIM to OTE and JWST-ICD-000727 INCC INSC IMC IFC Subsystem NIRCam Functional Requirements Document JWST-SPEC-002049 NIRSpec Functional Requirements Document JWST-SPEC-002060 FGS Instrument Performance and Functional Requirements JWST-SPEC-002069 MIRI Functional Requirements Document JWST-SPEC-002063 NRC NRS MIR FGS ISIM Structure Requirements JWST-RQMT-002087 ISIM Flight Software Requirements JWST-RQMT-002101 ICDH Requirements JWST-RQMT-000743 IFSW IST ICDH ISIM Requirements

12. Element ISIM to OTE and Spacecraft IRD JWST-IRD-000640 S/C Requirements JWST-RQMT-002039 ISIM Requirements JWST-RQMT-000835 Mission Assurance Requirements For the JWST Instruments JWST-RQMT-002363 ISIM FSW JWST-RQMT-002101 SC IOS-IR IFSW ISIM to OTE and JWST-ICD-001831 MAR ISIM S/C FSW Xxxx-xxx-xxxxxx IOSC Subsystem MIRI IRD JWST-IRD-000782 MIRI Functional Requirements Document (JWST-SPEC-002063) JPL D-24158 ESA JWST Product Assurance Requirements Document ESA-JWST-RQ-64 MIRI Mission Assurance Plan JPL D-25631 Component IMU MIR MAP PAR MIRI Dewar Requirements JPL D-25641 DWR MIRI FSW Requirements JPL D-24160 MIRI System Requirements (JPL) D-25646 MFSW SYS MIRI OBA Requirements EC MIRI-RS-00001 OBA JWST Requirements Flow Down to MIRI

13. ISIM-520 MIRI Field of View The minimum effective science field of view for the MIRI modules is 3.5 (TBR) sq arc min. (1.87 x 1.87 arc-min) MIRI FRD JWST Requirements Trace to MIRI FRD Rationale {OBS-552} The science instruments and FGS guider channels minimum unvignetted field of views in the OTE focal plane shall be equal to, or greater than the values shown in the table below. Table 3-15. Field of View Science Instrument FOV (arc-minutes) MIRI 2.4 x 2.4 • Minimum unvignetted field of view for imaging and spectroscopy. ISIM-235 Field of View The science instruments and FGS guider channels minimum unvignetted field of views in the OTE focal plane shall be equal to, or greater than the values shown in the table below. MIRI is 3.5 square arc-minutes. (1.87 x 1.87 arc-min) Allocation MIRI Allocation

14. Critical Issues List • Sensitivity • Pupil shear • Focus tolerance • Image quality - WFE/FWHM • Contamination • Dewar mass • Target acquisition • Observing efficiency

15. Dewar Mass • Requirement: The MIRI Cryo Dewar shall have a mass allocation of 208 kg, including cryogen, dewar mounting structure and margins. (RS-4.4-SYS- 0003) • Issue: The estimated mass of a Dewar that meets the Dewar performance requirements is greater than the allocation (228kg versus the 208kg allocation). • 5 year Operational lifetime after cool down and commissioning (FRD 3.5.2) • Instrument heat lift of 60mW (RS-4.5-SYS-0005)

16. IMU-817 Region 1 Component Allocations {OBS-637} ISIM Mass The MIRI Region 1 Assembly shall have a mass less than 311 kg, excluding external harnesses. Dewar RS-DWR-4.2-0012 Mass Mass: The total mass of the dewar including its supports to the ISIM at launch, including the margins as specified below shall not exceed 197.6kg. SysRD RS-4.4-SYS- 0003 Dewar Mass The MIRI Cryo Dewar shall have a mass allocation of 208 kg, including cryogen, dewar mounting structure and margins. Dewar Mass Requirement Trace Rationale • ISIM set the total mass allocation for MIRI for each region of the ISIM in the MIRI-ISIM IRD • The MIRI Requirements Document allocated the Region 1 mass of MIRI. 103kg were allocated to the OBA and 208kg to the Dewar. • Balance of the dewar mass is kept as system margin in the MIRI System Requirements Document (RS-4.4-SYS-0001) ISIM Mass ISIM-322 The mass of the ISIM shall not exceed 1,630 kilograms (TBR). MIRI Allocation Component Allocation

17. Options Current baseline estimate is 228kg. Detailed trade studies have shown opportunity for 10-15kg mass reduction Heat redistribution from FPM strap to OA strap Warmer OA interface temperature OBA cooled by ISIM to 40K On pad liquid helium cooling available Warmer end of life detector temperature Combine options 1 and 3 Combine options 1 and 4 Combine options 1 and 5 Combine options 1, 3 and 4 Combine options 1, 3, and 5

18. Status • Dewar RFP ready for release(March 2004) • Will get Dewar vendor on board by May • Options and trades will be settled once we have Dewar vendor on board to validate the mass estimates and options. • Based on vendor assessment we will revisit the Mass availability from ISIM • Trades: • Heat redistribution from FPM strap to OM strap • Has been accepted as new baseline. • Warmer OA interface temperature • Will be assessed, based on vendor response. • OBA cooled by ISIM to 40K • Under review with ISIM ICD team • On pad liquid helium cooling available • Visit to Ariane Space in April • Warmer end of life detector temperature • 0.2K increase to the detector operating temperature has been accepted. • Combine cases • Can combine cases 1 and 5 (14kg net savings) • Additional cases will be combined if net system savings found. Decision by May .

19. Target Acquisition Status • High Level requirements to support target acquisition will be worked out by MIRI PDR. • The target acquisition software will be written by the ISIM FSW group to requirements specified by the MIRI science team. • A working group is being established by the Project to work the details of target acquisition requirements with all instrument teams represented. Ray Kutina (STScI) will lead the working group. Meetings will start by the end of March. • Algorithms for centroiding will also be worked out by this group. • The IC&DH software implementation of target acquisition is scheduled for fall of ‘05, so there is some time to work out the IC&DH details.

20. {OBS-629} ISIM Efficiency Requirement Traceability for Observing Efficiency Rationale • MIRI Operations Concept Document, section 6, outlines a Month in the Life of MIRI, which is a very top level, very approximate operational scenario to estimate the time for MIRI operations. This operational scenario assumes a heavy weight on long exposures. We derived a 92% efficiency, however, given the uncertainty in operational scenario, we add margin and list a 89% efficiency for MIRI. • Telescope slews and similar operations are not counted against the MIRI operational efficiency ISIM 524 MIRI Efficiency After commissioning, the ratio of prime exposure time on scientific targets to total elapsed time, for the MIRI instrument, shall be greater than 95% (TBR) over a 5-year mission. MIRI Allocation FRD 3.4.3 FRD 2.4.2.3 FRD 3.4.1 Detector Annealing Efficiency Spectral Calibration Stability Setup, Cleanup and Mode Switching Wavelength calibration shall be required no more often than once per week … …specification within 2 hours (TBR) of the end of a detector annealing procedure. The MIRI operational efficiency shall be greater than 89 (TBR)%…. FRD 3.3.9 Instrument Turn-on Time … obtain science data within 30 minutes of turn on.

21. Observing Efficiency Status • The observing efficiency budget has been recognized as a project wide open issue and will be re-evaluated based on meetings of the observing efficiency working group led by Lionel Mitchell (GSFC). • Mitchell led a technical interface meeting on Friday, Feb. 27 to discuss observing efficiency with a project wide working group, including representatives from the project, OTE, space craft, ISIM, instrument teams and SOC. This meeting was an information exchange in which the instrument teams discussed the assumptions made for observing efficiency estimates. • The efficiency requirements are being re-cast in terms of overheads for the ISIM and SI subsystems. Due March 15, MIRI is working on an overhead time request for its operations. • This work, which began last October with the OTE and S/C will be continued with incorporation of an operational scenario based on a design reference mission (DRM) that is being developed at STScI with expectation of completion in the summer. • The observing efficiency working group is looking at operations assumptions and not instrument design.

22. RFA Categories Legend for Categories for all 97 ( including withdrawn): 1- Flow down from level 1 to FRD/IRD (ISIM lead), include critical issues 23 2 - Flow down to MIRI subsystems (MIRI lead) 5 3 - Software programmability 2 4 - In process tasks (design advisory) 7 5 - Mass management 5 6 - Sensitivity models 2 7 – Advisory and/or to be completed by PDR 25 8 – clarification 12 9 - Various/specific 4

23. Summary • JWST has completed requirements flow down to MIRI Instrument • MIRI requirements documents are in place • Project has excellent flow down and tracking process • All of the critical issues are being addressed; many have been closed out. • Most of the RFAs have been addressed. The remaining will be tracked to MIRI PDR.