1. PACS IQR 13 Jan 2005 IHDR Close-out1 Close-out of IHDR: Concerns / Recommendations A. Poglitsch

2. PACS IQR 13 Jan 2005 IHDR Close-out2 Major Concerns C1: The greatest concern the Board has is regarding the critical status of the DPU. Funding wise the situation is still not settled, however, the Board takes note that corrective actions have been initiated by ASI. … due to the instable funding situation during the past year, the activities at IFSI had been slowed down, and been stopped at its subcontractor, with detrimental effect on resolution of the hardware and software problems encountered and seriously hampering the warm electronics tests at MPE. Funding: de-facto approval, but waiting for signature by ASI. Schedule very tight.

3. PACS IQR 13 Jan 2005 IHDR Close-out3 Major Concerns C2: Regarding funding, the Board notes also with concern that the photoconductor arrays produced by ASTEQ are not yet fully funded. This will threaten the delivery of the FMs if no solution is found on a short timescale. Funding secured for FM + FS

4. PACS IQR 13 Jan 2005 IHDR Close-out4 Major Concerns C3: The representativeness of the CQM is of concern, as it will significantly deviate from the PFM (e.g. for the spectrometer the CREs, for the photometer the grounding, they both will be incomplete). Even with perfect flight-like conditions during the EQM tests it would be difficult to verify sensitivities and to optimise operating parameters. It will also be difficult to utilise the results as predictions for the FM; this is in effect a transfer of risk to the FM programme. Remains serious concern – in addition to the above mentioned problems, DECMEC was in a non- representative, poorly performing state for most of the CQM ILT.

5. PACS IQR 13 Jan 2005 IHDR Close-out5 Major Concerns C4: The Board notes with great concern that the presented ILT schedules, for FM and CQM, have been further compressed to the bare minimum. The Board agrees with PACS that any further compression, at subsystem and instrument system level, would have detrimental impact on the characterisation and the calibration of the instrument as well as on the IMT schedule. The Board sees this aggravated by the fact that also for the detector subsystems, i.e. for the PhFPU and bolometer arrays and also for the photoconductor arrays, the testing is already reduced to the minimum. 2 months of CQM ILT allowed ~1/3 of planned activities. 6 months for FM ILT as scheduled are tight, but not impossible.

6. PACS IQR 13 Jan 2005 IHDR Close-out6 Major Concerns C5: The Board notes that PA/QA at system and subsystem level still lacks the necessary methodology and control. This lack of coherent methodology and control is of particular concern in view of the deliveries of hardware at all levels, concerning the consistency and completeness of the delivery documentation i.e. the EIDP-End Item Data Package. In this respect, the Board welcomes and supports the PACS initiative to hold workshops on that subject to ensure a coherent approach across the consortium. Still not ideal, but significant progress made with EIDP for CQM/AVM delivery

7. PACS IQR 13 Jan 2005 IHDR Close-out7 Major Concerns C6: While most of the interfaces to the spacecraft are now agreed and frozen, the Board is concerned that for the Level 0 interface to the cooler and for the DECMEC there are still open design issues reported, despite the frequent interaction between PACS and Industry. L0 interface remains critical – present implementation by industry does not comply with PACS requirements and must be changed for FM. EQM tests pose risk on PACS FPU! DECMEC interface issues resolved.

8. PACS IQR 13 Jan 2005 IHDR Close-out8 Major Concerns C7: The presentations on the on-board software development gave a good visibility of the status and into the methodology for the DECMEC and the SPU. The status of the DPU, however, is still uncertain. The Board has the concern that the rigor needed for these developments is not being applied to the required level. In addition, the Board is concerned that the system aspects have not been sufficiently taken into account, despite the promising preliminary FDIR analysis. See CAPTEC recommendations which have not been implemented, yet – we are waiting for Project to organise final meeting with involved parties

9. PACS IQR 13 Jan 2005 IHDR Close-out9 Major Concerns C8: With first measurements of the transmission of the dichroic filters presented, the Board notes that the performance does not meet the specification. The Board is concerned that, if this cannot be improved for the FM this leads to reduced science performance and the science return will be compromised. FM filters are presently under construction. We have seen measurements on one modified dichroic sample with encouraging improvement. If both FM dichroics show equivalent performance we should reach requirement.

10. PACS IQR 13 Jan 2005 IHDR Close-out10 Major Concerns C9: Regarding the aspect of documentation and configuration control, the Board notes that the status of the delivered documentation, in particular for the mandatory documents, did not reach the expectations and the level required for this review. In particular the late delivery of some key documents as well as remaining inconsistencies between several documents made the Board’s evaluation of the data package more difficult. The Board understands that while for a number of system level documents the relevant activities to compile and/or update these on the basis of the sub-system level documents had not yet taken place due to higher priority tasks, other documents may have suffered from mishaps in internal configuration control. In this respect, the Board is pleased that PACS fully recognised the problem and that PACS agreed to correct it by the time of the next delivery. We keep trying…

11. PACS IQR 13 Jan 2005 IHDR Close-out11 Other Concerns C10: Given the results of the STM cryo-vibration tests, the decision to remove the CQM cryo-vibration at instrument system level is very risky. Agreed, but totally schedule-driven C11: The Kevlar conditioning and in particular the behaviour of the heat switch in the Cryo Cooler still comprise some mysterious elements, which currently do not seem to be fully appreciated. Much more information on Kevlar conditioning available from BFP tests (see report), but failure of one BFP Cooler / heat switch report late, but no problems during ILT

12. PACS IQR 13 Jan 2005 IHDR Close-out12 Other Concerns C12: The results of the Ge:Ga detector tests show ‘strange’ pixels. This behaviour needs to be understood and the pixel selection process to be mastered, as this affects the scientific performance. Regarding the sharing of tests between MPIA and MPE, the procedures at each site need to be clearly understood and harmonised as necessary. The cause of the ‘strange’ pixels could be identified as poor glue bonds. A new procedure has been developed and verified which will be applied for the FM detectors After a modification to the MPE test cryostat/optics, MPE and MPIA measurements agree quite well

13. PACS IQR 13 Jan 2005 IHDR Close-out13 Other Concerns C13: The effects of ionising radiation are not yet understood, however, tests are planned to address this issue by performing more representative measurements. Depending on the outcome and taking into consideration that since PACS needs to perform onboard data processing/compression there is a worry that this issue could grow into a major concern. First tests at the UCL light ion accelerator gave new insight in radiation effects. Thermal curing of detectors seems unavoidable – modification to detector heating necessary for FM. Impact on o/b data processing minor. Additional test campaign scheduled for more systematic study.

14. PACS IQR 13 Jan 2005 IHDR Close-out14 Other Concerns C14: The onboard error handling is rudimentary – if there is a problem PACS goes into safe mode, while there is no attempt at recovery. This approach can only work if the frequency of errors is very low, but this is not yet based on testing. Failure rate of WE units during ILT alarming. If this does not improve dramatically then PACS error handling is inadequate. With present S/W, FPU can be damaged by regular commands. Required actions will increase load on IFSI team.

15. PACS IQR 13 Jan 2005 IHDR Close-out15 Other Concerns C15: EMC testing on the CQM may not be sufficiently representative to reveal potential EMI problems (e.g. BOLC will utilise an external power supply for the CQM tests). Extensive EMC tests during ILT gave a detailed picture of the EMC status, with most units on internal power supplies. Internal power supplies exceed CE limits – t.b. discussed Measured H-field susceptibility agrees with simulation. IID-A levels not acceptable – serious performance degradation of photometer!

16. PACS IQR 13 Jan 2005 IHDR Close-out16 Board Recommendations R1: DPU Development The situation, funding- and engineering-wise, needs urgent resolution, as the DPU is the crucial element in the forthcoming ILT and EQM campaigns. Available DPU was sufficient for ILT. Burst mode does not work in EQM environment (yet).

17. PACS IQR 13 Jan 2005 IHDR Close-out17 Board Recommendations R2: Instrument Level Tests PACS shall ensure sufficient characterisation at subsystem and instrument level prior to the CQM campaign and ensure schedule consolidation between subsystems and instrument system. Done to the extent possible within given schedule constraints

18. PACS IQR 13 Jan 2005 IHDR Close-out18 Board Recommendations R3: Cryo Qualification PACS, with the relevant FPU subsystem teams, shall identify and, together with ESA, agree on a cryo qualification approach at FPU subsystem level. PhFPU – done Cooler – analysis in progress Ge:Ga detectors – new cryovibration planned FPU structure – new run for better definition of input loads on subunits planned

19. PACS IQR 13 Jan 2005 IHDR Close-out19 Board Recommendations R4: PA and Configuration Control PACS need to ensure that a method is followed by all and close collaboration is followed. We are trying hard

20. PACS IQR 13 Jan 2005 IHDR Close-out20 Board Recommendations R5: BOLC Configuration for FM Since, due to various reasons, for the CQM spacecraft level tests only an external power supply for BOLC will be available, the Board strongly recommends to ensure that for all PFM spacecraft level tests the flight model PSU shall be used. A detailed AIV approach, including testing at unit level and assembly sequence, needs to be elaborated by PACS. FM with PSU shall be available 11/2005 – late, but not too late.

21. PACS IQR 13 Jan 2005 IHDR Close-out21 Board Recommendations R6: Dichroics While it is understood by the Board that the filters for the PACS instrument are produced on a best effort basis, the Board would like to see the necessary design tradeoffs be made for the FMs. Done. Modified recipe reduces resonances without loss of mean transmission. Strong angular dependence of filter characteristics suspected from ILT, confirmed by FTS measurements on individual filters. Will make calibration more difficult and needs to be addressed in FM ILT.

22. PACS IQR 13 Jan 2005 IHDR Close-out22 Board Recommendations R7: Documentation The spreadsheet provided made it easy to navigate in the data package despite being split into several ‘deliveries’. However, it was not always clear whether a given document was ‘current’ or not, this was particularly true for ‘old’ documents, it is recommended that in the spreadsheet a ‘current to date’ column is added in addition to the issue date. It is also recommended that all documents have ‘readable’ file names. Available for IQR