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

2 MIRI Delta Systems Requirements Review 9 March 2004 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 Delta Systems Requirements Review 9 March 2004 MIRI has four Science Modes 1. Photometric Imaging 3. Coronagraphy 2. Low Resolution Spectroscopy

4 MIRI Delta Systems Requirements Review 9 March 2004 MIRI has four Science Modes 4. Integral Field Unit Spectroscopy

5 MIRI Delta Systems Requirements Review 9 March 2004 MIRI in the System S/C CTP MIRI OBA (7 K) MIRI Dewar (6.65 FPM Strap I/F OBA Strap I/F) Thermal Straps T Thermal Switch Temperature Transducer Valve Actuator S V DCE REGION 1 (37 K) REGION 2 ( K) REGION 3 (300 K) Launch-Critical Discretes /Passive Analog 1553B ICE IC&DH Routine Monitoring Discretes / Passive Analog Dewar I/Fs Under review RS-422 / 1553B (TBD) V T T T SpaceWire MIRI FSW MIRI FSW (TBD) FPE T S

6 MIRI Delta Systems Requirements Review 9 March 2004 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 MIRI Delta Systems Requirements Review 9 March 2004 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 MIRI Delta Systems Requirements Review 9 March 2004 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 MIRI Delta Systems Requirements Review 9 March 2004 Board Report Summary – Part II Group a) 1,3,4,5,9 and The flow down from the SciRD to the instrument system and subsystem architecture was spotty 3 Few presenters discussed the derived, flow down of the requirements, instead they presented designs that reflected their approach to meeting the assumed requirements. 4 Consistency of the OBA design approach with the requirements was not made clear to the Board. 5 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 MIRI Delta Systems Requirements Review 9 March 2004 Observatory Requirements

11 MIRI Delta Systems Requirements Review 9 March 2004 ISIM Requirements Segment ISIM to OTE and JWST-ICD ISIM to OTE and Spacecraft IRD JWST-IRD ISIM Requirements Document JWST-RQMT Element ISIM IOS-IR IOSC Mission Assurance Requirements For the JWST Instruments JWST-RQMT MAR ISIM to OTE and JWST-ICD NIRCam IRD JWST-IRD INCU INCC ISIM to OTE and JWST-ICD NIRSpec IRD JWST-IRD INSU INSC ISIM to OTE and JWST-ICD MIRI IRD JWST-IRD IMU IMC ISIM to OTE and JWST-ICD FGS IRD JWST-IRD IF IFC NIRCam Functional Requirements Document JWST-SPEC NRC NIRSpec Functional Requirements Document JWST-SPEC NRS MIRI Functional Requirements Document JWST-SPEC MIR FGS Instrument Performance and Functional Requirements JWST-SPEC FGS Subsystem ISIM Flight Software Requirements JWST-RQMT IFSW ISIM Structure Requirements JWST-RQMT IST ICDH Requirements JWST-RQMT ICDH ESA JWST Product Assurance Requirements Document ESA-JWST-RQ-64 CSA Performance Assurance Requirements CSA-TBD Fault Protection Requirements Document JWST-RQMT FP PAR JWST Observatory Specification JWST-SPEC OBS

12 MIRI Delta Systems Requirements Review 9 March 2004 JWST Requirements Flow Down to MIRI ISIM to OTE and JWST-ICD ISIM to OTE and Spacecraft IRD JWST-IRD S/C FSW Xxxx-xxx-xxxxxx Element Subsystem ISIM Requirements JWST-RQMT ISIM IOS-IR IOSC Mission Assurance Requirements For the JWST Instruments JWST-RQMT MAR ESA JWST Product Assurance Requirements Document ESA-JWST-RQ-64 PAR ISIM FSW JWST-RQMT IFSW MIRI FSW Requirements JPL D MFSW MIRI Dewar Requirements JPL D DWR MIRI OBA Requirements EC MIRI-RS OBA MIRI System Requirements (JPL) D SYS S/C Requirements JWST-RQMT SC Component MIRI Functional Requirements Document (JWST-SPEC ) JPL D MIR MIRI IRD JWST-IRD IMU MIRI Mission Assurance Plan JPL D MAP

13 MIRI Delta Systems Requirements Review 9 March 2004 JWST Requirements Trace to MIRI FRD {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 Field of View Science Instrument FOV (arc-minutes) MIRI 2.4 x 2.4 ISIM-235Field 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) 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) Allocation Minimum unvignetted field of view for imaging and spectroscopy. Rationale MIRI FRD MIRI Allocation

14 MIRI Delta Systems Requirements Review 9 March 2004 Critical Issues List Sensitivity Pupil shear Focus tolerance Image quality - WFE/FWHM Contamination Dewar mass Target acquisition Observing efficiency

15 MIRI Delta Systems Requirements Review 9 March 2004 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 MIRI Delta Systems Requirements Review 9 March 2004 Dewar Mass Requirement Trace Component Allocation 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) Rationale {OBS-637} ISIM Mass ISIM-322 ISIM Mass The mass of the ISIM shall not exceed 1,630 kilograms (TBR). SysRD RS-4.4-SYS- 0003Dewar Mass The MIRI Cryo Dewar shall have a mass allocation of 208 kg, including cryogen, dewar mounting structure and margins. MIRI Allocation The MIRI Region 1 Assembly shall have a mass less than 311 kg, excluding external harnesses. Region 1 Component AllocationsIMU-817 Dewar RS-DWR 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.

17 MIRI Delta Systems Requirements Review 9 March 2004 Options Current baseline estimate is 228kg. Detailed trade studies have shown opportunity for 10-15kg mass reduction 1. Heat redistribution from FPM strap to OA strap 2. Warmer OA interface temperature 3. OBA cooled by ISIM to 40K 4. On pad liquid helium cooling available 5. Warmer end of life detector temperature 6. Combine options 1 and 3 7. Combine options 1 and 4 8. Combine options 1 and 5 9. Combine options 1, 3 and Combine options 1, 3, and 5

18 MIRI Delta Systems Requirements Review 9 March 2004 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 MIRI Delta Systems Requirements Review 9 March 2004 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 MIRI Delta Systems Requirements Review 9 March 2004 Requirement Traceability for Observing Efficiency {OBS-629} ISIM Efficiency FRD Setup, Cleanup and Mode Switching The MIRI operational efficiency shall be greater than 89 (TBR)%…. MIRI Allocation 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 Rationale 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. FRD Detector Annealing Efficiency FRD Instrument Turn-on Time FRD Spectral Calibration Stability …specification within 2 hours (TBR) of the end of a detector annealing procedure. Wavelength calibration shall be required no more often than once per week … … obtain science data within 30 minutes of turn on.

21 MIRI Delta Systems Requirements Review 9 March 2004 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 MIRI Delta Systems Requirements Review 9 March 2004 RFA Categories Legend for Categories for all 97 ( including withdrawn): 1- Flow down from level 1 to FRD/IRD (ISIM lead), include critical issues Flow down to MIRI subsystems (MIRI lead)5 3 - Software programmability2 4 - In process tasks (design advisory)7 5 - Mass management5 6 - Sensitivity models2 7 – Advisory and/or to be completed by PDR25 8 – clarification Various/specific4

23 MIRI Delta Systems Requirements Review 9 March 2004 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.