mid-infrared instrument (miri) delta-systems requirements review: march 9

Mid-InfraRed Instrument (MIRI) Delta-Systems Requirements

Review: March 9

Margaret Meixner

MIRI support scientist

2MIRI 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.


MIRI has four Science Modes

1. Photometric Imaging

3. Coronagraphy

2. Low Resolution Spectroscopy


MIRI has four Science Modes

4. Integral Field Unit Spectroscopy


MIRI in the System

S/C CTP

MIRI OBA(7 K)

MIRI Dewar (6.65 K @ FPM Strap I/F6.85K @ OBA Strap I/F)

Thermal Straps

T

Thermal Switch

Temperature Transducer

Valve Actuator

S

V

DCE

REGION 1(37 K)

REGION 2(75-300 K)

REGION 3(300 K)Launch-Critical

Discretes /Passive Analog

1553B

ICE

IC&DH

Routine MonitoringDiscretes / Passive Analog

Dewar I/FsUnder review

RS-422 / 1553B (TBD)

V

T

T

T

SpaceWire

MIRIFSW

MIRIFSW(TBD)

FPE

TS


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


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


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.


Board Report Summary – Part II

Group a) 1,3,4,5,9 and 11

1. 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.


Observatory Requirements

JWST-ICD-002001 JWST-ICD-001998

JWST Program PlanJWST-PLAN-000633

Program

System

JWST PerformanceAssurance Requirements

JWST-RQMT-000650

JWST ScienceRequirements Document

JWST-RQMT-002558

Segment

Performance QualityAssurance Plan

JWST-PLAN-002412

Contamination ControlPlan

JWST-PLAN-002028

JWST ObservatorySpecification

JWST-SPEC-002020

Environmental Req’sfor the JWST Observatory

JWST-SPEC-003149

EMC Control PlanJWST-PLAN-002449

WFS&C RequirementsAllocation DocumentJWST-RQMT-002017

Ground SegmentRequirements

JWST-RQMT-001056

JWST SystemVerification Plan

JWST-PLAN-002027

Flight Observatory toGround Segment IRD

JWST-IRD-000696

Observatory to LaunchSegment IRD

JWST-IRD-002000

NIRCam OCD

NIRSpec OCD

FGS OCD

Radiation RequirementsAllocation SpecificationJWST-SPEC-000871

ISIM to OTE and

JWST-ICD-001831

Fault ProtectionRequirements Document

JWST-RQMT-002450

ISIM to OTE and Spacecraft IRD

JWST-IRD-000640

OTE SpecificationJWST-RQMT-002021

SC Requirements DocumentJWST-RQMT-002039

ISIM RequirementsDocument

JWST-RQMT-000835

Element

Spacecraft to OTE ICD

D35231

L1

SR

JWST MissionRequirements

JWST-RQMT-000634MR PA

GS OBS

ISIM

EVRD

WFSCCPPQ

EMC

OL

OLC

FP

FG

FGC

IOS-IR

IOSC

OTESOICSC

BudgetsWFE Rev Q 03-JWST-0405

EfficiencyPointing

D36128

Observatory to GSE IRDD36127 OG

OGC

Observatory I&T PlanJWST-PLAN-002030

JWST Mission OperationsConcept DocumentJWST-OPS-002018 MOC

MIRI OCD


ISIM Requirements

Segment

ISIM to OTE and

JWST-ICD-001831


JWST-IRD-000640

ISIM RequirementsDocument

JWST-RQMT-000835

Element

ISIM IOS-IR

IOSC

Mission Assurance RequirementsFor the JWST Instruments

JWST-RQMT-002363MAR

ISIM to OTE and

JWST-ICD-000728

NIRCam IRDJWST-IRD-000780

INCU

INCC

ISIM to OTE and

JWST-ICD-000729

NIRSpec IRDJWST-IRD-000781

INSU

INSC

ISIM to OTE and

JWST-ICD-000730

MIRI IRDJWST-IRD-000782

IMU

IMC

ISIM to OTE and

JWST-ICD-000727

FGS IRDJWST-IRD-000783

IF

IFC

NIRCam FunctionalRequirements Document

JWST-SPEC-002049NRC

NIRSpec FunctionalRequirements Document

JWST-SPEC-002060NRS

MIRI FunctionalRequirements Document

JWST-SPEC-002063MIR

FGS Instrument Performanceand Functional Requirements

JWST-SPEC-002069FGS

Subsystem

ISIM Flight Software RequirementsJWST-RQMT-002101

IFSW

ISIM Structure RequirementsJWST-RQMT-002087

IST

ICDH RequirementsJWST-RQMT-000743

ICDH

ESA JWST Product AssuranceRequirements Document

ESA-JWST-RQ-64

CSA Performance AssuranceRequirements CSA-TBD

Fault ProtectionRequirements Document

JWST-RQMT-002450FP

PAR

JWST ObservatorySpecification

JWST-SPEC-002020OBS


JWST Requirements Flow Down to MIRI

ISIM to OTE and

JWST-ICD-001831


JWST-IRD-000640

S/C FSW Xxxx-xxx-xxxxxx

Element

Subsystem

ISIM RequirementsJWST-RQMT-000835

ISIMIOS-IR

IOSC

Mission Assurance RequirementsFor the JWST Instruments

JWST-RQMT-002363MAR

ESA JWST Product Assurance

Requirements DocumentESA-JWST-RQ-64

PAR

ISIM FSW JWST-RQMT-002101

IFSW

MIRI FSW RequirementsJPL D-24160

MFSW

MIRI Dewar RequirementsJPL D-25641 DWR

MIRI OBA RequirementsEC MIRI-RS-00001

OBA

MIRI System Requirements(JPL) D-25646

SYS

S/C RequirementsJWST-RQMT-002039

SC

Component

MIRI FunctionalRequirements Document

(JWST-SPEC-002063)JPL D-24158 MIR

MIRI IRDJWST-IRD-000782

IMU

MIRI Mission Assurance Plan

JPL D-25631MAP


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 3-15. Field of View Science Instrument FOV (arc-minutes) MIRI 2.4 x 2.4

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)

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


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


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)


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- 0003 Dewar 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-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.


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



9. Combine options 1, 3 and 4

10. Combine options 1, 3, and 5

240

230

220

210

200

1901086420

Option

single option combination of options


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


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.


Requirement Traceability for Observing Efficiency

{OBS-629} ISIM Efficiency

FRD 3.4.1Setup, 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 524MIRI EfficiencyAfter 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 3.4.3Detector Annealing Efficiency

FRD 3.3.9Instrument Turn-on Time

FRD 2.4.2.3Spectral 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.


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.


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


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.

mid-infrared instrument (miri) delta-systems requirements review: march 9

Documents

miri delta srr

miri principals

science requirements

requirements documentation

requirements flowdown

assumed requirements

entire miri team

miri srr45 rfas