CCD Imaging Spectrometer
|Submitted to:||Submitted by:|
George C. Marshall Space Flight Center
National Aeronautics and Space Administration
Marshall Space Flight Center, AL 35812
Center for Space Research
Massachusetts Institute of Technology
Cambridge, MA 02139
This report covers the period October 1996.
A monthly status review for ACIS was conducted on October 3 at LMA. The AXAF Project Office was represented by Max Rosenthal, Nes Cumings and Tony Lavoie. Due to schedule conflicts, neither Mark Bautz nor Gordon Garmire were able to attend. At the conclusion of this review, a schedule meeting was held with the Project and six delivery options were identified. These options were evaluated by MIT over the following weeks and five of the possibilities have been incorporated into the weekly PERT Chart updates provided to the Project. The next monthly review will be held on November 21 at MIT.
ACIS participated in the weekly AXAF telecons on October 1, 8, 15, 22, and 29. ACIS participated in the FPSI telecons on October 16 and 30. The review that normally would have been held on Oct 2 was cancelled due to the monthly review the next day (see above).
The ACIS schedule is still dominated by the refurbishment of the CCDs which, until now, has been predicated on obtaining flexprints that can undergo the thermal cycling expected on orbit. The good news here is that the thermal problem seems to be solved - one sample from each panel has undergone thermal cycling and to date not one failure has been experienced with the new flexprints and many have completed a 250-cycle test. However, we have had other general quality problems with the new flexprints. As discussed below, the second set of flexprints from Speedy Circuits was found to have a fabrication flaw (cut traces) and only one unit survived incoming inspection at Lincoln Lab. That one unit was successfully installed on a flight CCD, delivered to CSR on September 27, and passed science calibration by mid-October.
Given the cut trace problem with lot 2, Speedy immediately began yet another lot of flexprints. This lot was divided into two subsets (A and B). Lot 3A was completed by the end of September, but all coupons failed at Speedy due to `plating folds', later traced to a change in the drilling speed and feed parameters. Lot 3B was delivered on October 12. This lot also had some 'plating folds' but much less severe than 3A.
One panel was accepted by Lincoln and, upon examination by MSFC, a second panel was accepted in early November. Therefore, a total of about 18 flexprints are considered 'flight quality'. Given this performance, Speedy began the fabrication of lot 4 in late October. In the meantime, the `via-less' flexprints from Speedy Circuits were delivered on October 8. Although these also had some quality issues, a fair number are considered acceptable for flight. For now, these are being held as 'Plan B' since sufficient 'with via' units are available to begin work on the CCDs.
By the end of October, the flexprint issue was well enough in hand to begin the re-flexing of existing CCDs. Unfortunately, another problem struck. The first two flight units to be re-flexed (one calibrated and one not yet calibrated) were lost due to ESD problems. The re-flex operation was halted and a careful audit of the facility and procedures was conducted. By the end of October, it was determined that several problems existed, the most significant of which was probably the lack of humidity in the CCD re-flex and assembly area. Steps were initiated to correct these problems. In this area, TRW has provided the services of an ESD expert who provided verbal advice in early November and will visit the Lincoln facility during the third week of November.
The following is a brief summary of the status of the other ACIS elements:
Since it now appears that the 'ACIS-2C' will be the primary MIT unit for the XRCF activities, calibration began on November 1 of the two CCDs (one FI and one BI) that will be installed in the 'ACIS-2C' for the AXAF calibration runs next spring. This calibration is expected to be completed by Nov 22.
The conformal coating of the DEA Analog Boards was completed on October 31 and these were immediately placed in a thermal vac chamber to complete the 1443 processing.
The DPA printed circuit boards (FEPs and BEPs) completed testing and were being conformally coated at Assurance Technology Corp at the end of October.
The first two sets of the new OBFs were acoustically tested at LMA by mid-October. Two additional sets are still in fabrication and due for delivery in early November.
The DEA Interface and Thermal Control flight boards were sent to Sanders for loading on October 15. Identical engineering units have been fabricated and will be used in the initial assembly of the flight DEA, with substitution being made upon return from LMA in January.
Due primarily to the delays in the receipt of flight quality flexprints and then the ESD problems experienced with the first two attempts to re-flex flight units, the ACIS schedule continued to slip in October. The delivery date of a full ACIS Instrument, fully verified, is now projected to be May 10. As described above, MSFC has defined many options (e.g., use engineering unit Detector Assembly, do T-V test after XRCF, etc.), all of which result in an earlier delivery, but would require a return to MIT for completion of the verification activities.
Due to the uncertainty of the hardware schedule, as discussed above, no additional layoffs were announced in October. However, layoffs made earlier were allowed to go to completion. Marty Furey (structural engineer) officially left the project on October 14, and Jeanne Repec left the project on October 30.
Calibration was completed on four devices: w163c3, w168c2, w158c2 and w158c4r. The last of these is the only calibrated device with a flight-qualified flexprint. Aside from devices designated for use in ACIS 2C, all flight candidate devices have now been calibrated.
Steve Jones made significant progress on analysis software that (almost) automatically extracts gain, resolution and relative detection efficiency summaries from all data available for any specified device.
We completed analysis of the flight analog board evaluation data obtained in August and September. One of 12 boards evaluated (analog board s/n 02) was found to have (just) measurably higher noise than the other 11 (3.0 electrons for s/n 02; 2.6 +-0.15 for the other 11). As expected, the noise on the flight boards is higher than that of the calibration boards; the difference is probably due to housekeeping circuitry on the flight boards. Linearity, as determined by gain differences at 525 and 5900 eV, is excellent: gain changes by no more than 0.2% over this range. Gain variations among the boards are of order 5%, which is comparable to or less than the node-to-node gain variations for a typical CCD.
The XRCF rehearsal with the two-chip ACIS was completed, and plans were finalized for changing the CCDs and electronics. During HRMA calibration, ACIS-2C will contain one front-illuminated CCD (w97c1) and one back-illuminated CCD (w148c4). These CCDs will be calibrated at MIT CSR, with HETE analog electronics, during November.
The ACIS Contamination Monitor (Door Source) flight unit parts are at LMA and MSFC for bake-out and 1238 certification. The External Calibration Source flight unit parts are at LMA for bake-out and 1238 certification.
Two of the Flight BPAs are at LMA for bake-out and 1238 certification. The third unit is being used to assist in flight cable assembly.
The parts of the Proton Shield parts are at LMA for bake-out and 1238 certification.
Drilling the holes for the pins which locate the panels is complete and the panels are on their way to painting. The Flexures have been mounted on the BASD supplied template and the holes for the pins are being drilled.
The flight unit was completed and shipped to LMA for cleaning and baking when an interference was found. The assembly has been returned to MIT. A new cable clamp has been designed and is being machined.
The LMA engineer and technician have been here and have completed the upgrades to the EU DA.
A hoist and Tipper Cart are being cleaned and bagged prior to a fit check of the SIMSim at Lincoln Labs. The EU Radiators have been assembled to the SIM-Sim. The chiller assembly has been tested with the EU DA. The Focal Plane did not reach the low temperature intended. Modifications are planned to the chiller assembly to improve its performance.
The DPA and DEA assembly drawings have been released. Support of the flight assembly continues.
The ACTEL lead failure analysis has been completed. From the data collected from the vibration test and Seal Laboratory, the deflection of the unsupported board caused the leads to break. The flight configuration of the boards are well supported and this failure mechanism should not occur once the boards are fully assembled. To further secure the flight ACTELS, the boards have been reworked to add spotbond to each corner.
On October 31, MIT and LL personnel began a two-day fitcheck at the LL of the major pieces of mechanical GSE to be used for the ACIS TV Test. The MIT crane and lifting fixture were used to lift the LMA-fabricated SIMSIM, with EU radiators, out of its shipping container. The SIMSIM was placed on the MIT tipper cart, rolled to the TV chamber, rotated 90 degrees, and bolted into the chamber. Feedthrough plates on the chamber wall and door were also checked for alignment. The PSMC mounting plate was bolted to the chamber. Some changes will be made to the rails which support the SIMSIM in the chamber. Because of interference with the cold shroud on the chamber door, the ACIS will be positioned further (10") into the chamber than was baselined.
Heaters for the PSMC mounting plate were received and their resistances were verified. The mounting plate was received and will be painted before the TV Test.
Because of concern over the DEA A/D converter latchup problem, a conservative thermal analysis was performed assuming a hotspot within the die of 0.66W concentrated within a silicon box of 15x15x10 microns. The hotspot temperature was calculated at less than 148°C. The component is rated up to 190°C by the manufacturer.
MIT reviewed thermal handouts for the SIM Delta CDA, held at Ball from Oct. 15-17. MIT recommended some changes in the ACIS properties used by Ball in the ISIM thermal model and in the DEA hot limit.
The Z93P white paint baselined for the -Y panel of the DPA exhibited flaking after a prebake at 125°C. MIT recommended, and the ACIS Project approved, repainting the panel with Aeroglaze Z306 black
The DEA Engineering unit is now fully operational.. Simulated x-ray images from all DEA video subsystems have been acquired and analyzed via flight software and the DPA. In addition, the PSMC power system has been totally integrated into the performance evaluation without error.
Flight system integration continues to proceed. Flight 11th and 12th cards are ready for testing. Flight backplane and video subsystems have been conformally coated and are ready for testing. Flight cable assemblies and electronic housing structures are close to completion.
Testing (and retesting) of flight boards is ongoing.
A complete set of DPA boards has been loaded into the flight backplane and we have just started system testing.
Harnesses for in-house testing were completed by Lincoln Laboratory and checked for correctness at MIT.
Supported GSE set up for and testing of the DPA.
No flight software ECOs were generated this month. All changes will be collected into a single ECO that will be reviewed along with the Beta release of the software.
Test tools were updated to reflect the recently published RCTU channel assignments. Peter Ford met with Roger Brissenden (ASC), Tim Crumbley, Steve Purinton, and Allyn Tennant (all MSFC) to review plans for long-term ACIS maintenance.
The Beta version of the Flight Software is due be burned into the flight and engineering boards in mid-November. It will be accompanied by a new release of IP&CL structures and notes. The calibration team has been asked to assist the software engineers in providing default tables to be compiled into the Beta software, i.e.
All BEP and FEP flight software modules continue to be subjected to unit and coverage tests.
High-level testing of flight software in FEP and BEP hardware continues, accompanied by tests using the software simulators.
Ten new software problem reports have been filed, of which 5 have been closed out. A total of 15 problem reports are outstanding. These may be viewed at "http://acis.mit.edu/axaf/spr/".
Since an increasing number of problem reports are related not to the flight software itself but to the processScience test tool, the decision was taken to rewrite that program. The new tool, named psci, is being prototyped and will replace processScience when the Beta version of the flight software is released.
As a result of discussions between MSFC and MIT, Rhonda Schrimsher and Bob Rowe (MSFC) spent two weeks at MIT to familiarize themselves with the ACIS instrument. They will assist MIT in performing software verification tests.
Eight (8) Alerts from NASA/MSFC, were received over the report period. These items are listed below. Each Alert was compared with the available MIT parts lists. One of the Alerts listed below impacts the MIT ACIS design at this time. JANTXV2N2222A from New England Semiconductor Inc., lot-date-code 9522 is used in the DPA and DEA. One hundred fifty (150) parts were purchased and all are accounted for. These parts are being purged from stock, removed from kits, and replaced in assembled flight printed circuit boards.
|ALERT #||MSFC #||Part Number and Manufacturer||Part or Material Name|
|MMC-ET-RA07b-040||6978||MS51832 GENERIC||SCREW THREAD
|NASA PRELIMINARY||6979||55L11-7T LANGLEY||NAFLEX SEALS|
|NASA PART ADVISORY
OPTEK TECHNOLOGY INC.
NEW ENGLAND SEMI. INC
Conducted contamination training for twenty (20) ACIS personnel.
Removed the SIM from the shipping container from LMA and performed incoming visual inspection.
Shipped two Thermal Control/Interface kits to Lockheed Sanders for assembly.
Performed MIT Source Inspection at Harris Semiconductor on Line Receiver Microcircuit, P/N HS1-26C32RH-8.
Received results of six (6) Speedy Circuits and Hi-Rel rigid coupons cross section analysis from GSFC (Diane Kolos), on the Thermal Control/Interface board in the DEA. All six (6) were judged acceptable. Hi-Rel failed all six (6) coupons for delamination between the copper interlayer and the prepreg. This is the second 100% coupon failure from Speedy Circuits on this same printed circuit board. The Speedy Circuits and Hi-Rel cross-sections were then sent to Jim Blanche at MSFC for review. Again, the coupons were judged acceptable by MSFC. The printed circuit boards are now in assembly at Lockheed Sanders.
|Waiver #||Description||LMA/LL/ MIT||Submittal||Approval|
|36-001||printed circuit annular ring||LL||6/28/95||7/26/95|
|36-002||NHB5300.4 (3A-!) Soldering||LMA||11/17/95||1/30/96|
|36-003||NHB5300.4 (3J) Conformal Coating||LMA||11/17/95||1/30/96|
|36-004||NHB5300.4 (3G Cable, Harness, and Wiring NHB5300.4(3H) Crimping and Wirewrap||LMA||11/17/95||1/30/96|
|36-006||NHB5300.4 (3K) Printed Wiring Boards||LMA||11/17/95||1/30/96|
|36-007||3% Reflectance loss on OWS for MSFC-SPEC-1238 testing||MIT||2/8/96||OPEN|
|36-008||AWG26 nickel wire from DA to DEA||MIT||2/7/96||WITHDRAWN|
|36-009||jumper wires to part leads||MIT||7/16/96||8/20/96|
|36-010||Continuity, IR, and DWV test after harness/cable installation||MIT, LL, and LMA||7/16/96||IN PROCESS|
|36-011||RCTU serial interface circuit resistor||MIT||11/7/96||IN PROCESS|
Waiver 36-007 is being revisited by MSFC in light of the decision not to bake-out the optical bench.
Harness/cable assembly drawings were requested by MSFC to support waiver request 36-010. These have been submitted to MSFC.
|36-002||A to D Converter
|36-003||CA Memory Module
|36-004||FB Memory Module
|36-005||Programmable Supply current
Op Amp 36-02304
Only Memory 36-02306
|36-008||Electrical Connectors, PCB
Mount SND Type
|36-009||Electrical Connectors, PCB
Mount KA Type
|36-012||Junction Field Effect Transistor
|36-013||Dual Surface Mount Diode
|36-014||Dual Operational Amplifier
|36-015||8000 Gate Anti-fuse Field
Programmable Gate Array
|36-017A||Charge Coupled Device
|36-018||Microcircuit, Octal Buffer
|36-019||Microcircuit, Octal Bus
Transceiver (Harris HCS245)
Flip-Flop (Harris HCS374)
Line Driver (Harris HS26C31)
Differential Line Receiver
Q-Tech part type
WIMA P/N FKP2 (36-02312)
|36-025||Wire, Electrical, Nickel
Wirecraft P/N E267U9N
|36-027||Wire, Electrical, Nickel
Specialty Cable AWG26
WIMA P/N FKP2 per
CECC 31 800
(3M-20 pin Connector/Header)
|Microcircuit, High Voltage
|Microcircuit, Rad Hard
(Harris P/Ns FRL130R3,
FRL913R3, and FRE9160R3)
|Relay, Latching, DPDT, 5A
|Microcircuit, Logic, HC
|Diode, Rectifier, Schottky
|Transistor, Power Switching
(Lockheed MLP 95215-002)
|Resistor, Precision, Low TC
Miniature (YSI 20020075P5)
Platinum (Rose mount 0118BRA)
|Magnetic Devices -
Transformers and Inductors
(LMA P/N 849AC410952-XXX)
Radiation testing has been completed at Space Electronics Inc. (SEI) on twenty-four (24) device types. Results of these tests are listed below.
|Manufacturer||Part Number||Radiation Test
|Analog Devices||DAC8800BR/883||<2K Rads|
|Com Linear||CLC505A8D||>100K Rads|
|Harris (Chip Supply)||36-02305 (CA 3080)||<100K Rads|
|Analog Devices||OP220AJ/883 (TO-5 can)
|< 20K Rads|
|Texas Instruments||TL082/883B||>100K Rads|
|Analog Devices||REF43BZ/883||>200 K Rads|
|> 100K Rads|
|> 100K Rads|
Devices which have not passed 100K Rads of Co60 testing will be shielded or design work-arounds will be implemented.
Two (2) new flight Optical Blocking Filters (OBFs) have been ordered from Luxel. These are replacements for OBFs which have been damaged through handling during test.
Sent 15 MUAs to MSFC. The status of the MUAs shows that there are 22 waiting review by MSFC and 16 approved MUAs.
Investigated what environmental tests will be performed on the assemblies containing radioactive sources. Sent a fax to H. Hooper at MSFC addressing these tests, so that he can update his hazard report (HR F-05C).
For ACIS SW verification, a test procedure describes what requirements are to be tested. This may result in many test scripts, but for purposes of reporting, we track the completion of all scripts produced as a result of a procedure, as a single entity. MIT has thus far developed 12 of 37 test procedures. During this reporting period, 4 were generated: Packet, Graded, Reset, and Graded-Threshold.
MIT has developed and run on engineering hardware 3 test script sets. During this reporting period, 2 were generated: Window (2D), and Threshold.
Reviewed the replacements for Process Science and other Test Tools
There have been 16 new problem reports identified this reporting period.
There are a total of 65 problem reports identified. Of those:
There has been no activity on the Performance Assurance and Safety (PAS) Plan. The PAS Plan in effect is Revision B.
The DPA panel, originally painted white, was sent to Boyd Coatings for application of black paint. This panel was completed by Boyd, delivered to MIT and was vacuum-baked. All of the DEA and DPA panels are now completed through painting, cleaning, and vacuum baking.
Five FEPs and 3 BEPs have been conformally coated by ATC and they are being vacuum-baked.
The FEP and BEP aluminum frames were cleaned and vacuum-baked.
The support structure was assembled, drilled, pinned, cleaned and sent to Boyd Coatings for painting.
Picked up the 11 Video Boards from Sanders and vacuum-baked them.
Cleaned and vacuum-baked the DPA internal harnesses.
Picked up the three Thermal Interface Beryllium frames from Phoenix Precision. Performed a fitcheck with these frames on the Engineering 11th and 12th boards with no obvious problems. The frames were cleaned and vacuum-baked.
The 11th and 12th engineering boards were cleaned and vacuum baked.
The flight x-ray sources have been returned to MIT from cleaning and 1238 certification by MSFC.
The DEA and DPA Backplanes and the PDU were conformally coated and vacuum-baked.
The tantalum shields were painted, cleaned and vacuum-baked.
Cleaned and vacuum-baked the four external cables.
Cleaned 3 Spectrometer and 2 Imager OBF shipping containers and sent them to Luxel.
Ten wafers from Lot 14 have gone through the scratch glass process and we have obtained 5 grade A chips and 11 grade A-. Under Mark Bautz's direction, we will saw the grade A parts first and package them, rather than using the inventory of 9 sawn A- parts from Lot 6.
Attempts to re-flex flight parts have been impeded by the creation of shorts in the image array, probably due to ESD problems. The weather has turned colder and the relative humidity in the bonding area has reached 16%, which is not conducive to high packaging yields. We are attempting to use portable humidifiers to remedy this situation. We are also conducting an audit of the packaging area for ESD trouble spots and we expect to receive assistance from personnel at TRW. Improvements that are being implemented include the introduction of a static dissipative floor, ESD-safe chairs, calibration and balancing of the air ionizers, and retraining in following good ESD-safe practices.
A shipment of 24 conventional design flexprints from Speedy Circuits has arrived. These are all of the flexprints from two panels designated lot 3B. Five of these flexprints were rejected by the vendor for workmanship problems but were shipped at our request because they were deemed suitable for thermal cycling and sectioning. Cross section results from coupons and two of the non-flight quality flexprints showed that one of the two panels was clearly acceptable while the second panel has burrs in the vias as a result of the drilling operation. These burrs lead to plating folds and voids when the copper plating is deposited. The significance of these defects will have to be evaluated. The better of the panels yielded 10 flexprints for use with the flight detectors. Assembly and precision cleaning of these parts has been completed.
To establish the possible consequences of these plating folds and burrs, two flexprints with the worst looking vias were subjected to 400 rapid thermal cycles. This consists of dunking the detector end of the flexprint into liquid nitrogen followed by rapid heating with a hot air gun. Electrical testing revealed no opens had developed. Cross-sectioning of the samples revealed no cracks or delaminations associated with the plating voids and folds. Thus, it would appear that these defects (at the degree seen on these flexprints) do not impact thermal cycle lifetime.
One flexprint from each of the two panels was loaded with components and mounted to an alumina substrate. Flexprint attachment included the redundant back junction connection described in the last progress report. These samples have started slow thermal cycle testing between -150° and +60°C. They will be characterized periodically as they accumulate 200 thermal cycles. As of the end of October, 46 cycles had been successfully completed with no via or back junction connection failures.
Because of the low yield from the above-mentioned lot, Speedy Circuits fabricated an additional lot (designated lot 4) which yielded 63 acceptable units under the Speedy Circuits criteria. However, coupon sectioning at Lincoln revealed that all of the panels have significant via hole quality problems. These problems are of the same type but much more severe than those seen in the previous lot. Two flexprints from this lot were also subjected to 400 rapid thermal cycles. Once again, electrical testing revealed that no opens had developed. These parts will be sectioned to determine if the vias show any signs of impending failure. Additional work will be needed to establish the suitability of these parts for flight use.
The "vialess" flexprints from Speedy Circuits have arrived. While some of these parts are acceptable for flight use, many have unacceptable defects. The most prevalent problem is cracks running across the gold plated traces at the end of the circuit where wirebonding to the detector is performed. In some cases, this results in an electrical open circuit but, in most cases, there is still continuity across the defect.
Two flexprints from this lot were subjected to 200 rapid thermal cycles. The purpose was to evaluate the Dupont material used in these circuits (rather than Sheldahl as described in last month's report) and to demonstrate the integrity of the back junction connections. Flexprints with cracked traces were used for this test since they are of the lowest value.
Both samples were mounted to alumina substrates to induce the stresses associated with the flexprint/alumina interface during thermal cycling. Electrical testing during and after cycling revealed that the back junction connections survived intact. However, it was noted that several of the traces that initially were conducting, despite having cracks, had become open circuits. This would indicate that flexprints that are free of these defects are suitable for flight use but that no consideration should be given to using flexprints that have any evidence of cracks in the traces. Approximately 18 vialess flexprints are expected to be rated flight quality.
Nine flexprints (one from each panel that supplied parts) are being prepared for slow thermal cycling. Successful completion of 200 thermal cycles is required before these flexprints can be used on flight detectors.
A mock-up of the ACIS detector assembly (all ten detectors) was put together to verify that the "vialess" design would not interfere with the camera housing. A spare electrical connector plate (provided by CSR) was integrated with the detector assembly to verify that existing tooling and procedures would be compatible with the "vialess" flexprints. No integration problems were discovered during this trial. However, the procedure used for application of low thermal emissivity tape on the flexprints was modified to produce better-shaped service loops.
Graphics Research has had additional delays in fabricating convention design flexprints. It is now expected that they will be complete by 5 November 1996. The delay is due to a backlog in their production facility rather than problems with our job. Work continues on their production of the "vialess" style flexprints. These are expected to be complete 15 November, 1996.
At this time we have enough flight-quality flexprints to start assembly of the flight detectors. Additional flexprints, if of good quality, should arrive soon enough to allow assembly to continue uninterrupted. Attention now must be focused on the possible causes for the failure of the two flight devices during flexprint replacement.
We believe the packaging process will resume by mid November, after the ESD issues are resolved.
During this month Change Orders 59 which defined Change Order 41 was received. Based on this action, Change Order 48 is the only outstanding change order to the LMA contract remaining to be defined. Change order 58 was also received. This Change Order changes the program plan due to the delay in the planned delivery of the ACIS Instrument to 3/15/97 and adds several other specific tasks to the contract. Firm proposal preparations were initialed with a proposal submittal planned for 11 November 1996. Work is continuing against this Change Order to enable delivery of the flight ACIS instrument by a promise date of 15 March 1997.
The monthly ACIS NASA/MIT Monthly Status Review and MIT/LMA Technical Interchange meetings were conducted at LMA this month. Both of these activities were planned for early October. Specific emphasis was placed on the need to develop optional instrument integration and test scenarios to assure meeting a schedule that will allow ACIS testing at XRCF.
Major accomplishments for October included completion of cleaning of the Radiator Shipping Container making the Flight Radiators ready for integration, Flight TCS Shades were transported to BASD for NASA-SPEC-1238 bake, refurbishment was completed and testing initiated for VGSE #1, fabrication of an Engineering Unit (EU) Venting Subsystem was initiated, fabrication was completed and testing initiated of the Flight Cabling, PSMC board checkout and initial box assembly was completed, PSMC procurement was completed, and the acoustics testing of the Flight OBFs was resumed. In addition, precision cleaning of MIT Detector Housing parts was initiated, the EU Radiators were shipped to MIT for LL chamber fitcheck, the Engineering Unit Detector Housing was upgraded to the flight configuration at MIT, and LMA supported the Science Instrument Module (SIM) CDA at Ball Aerospace.
The program reviewed inter-company Mission Success Bulletins and GIDEP ALERTS received during the month. None of these ALERTS were judged to be applicable to any of the parts or components being used by LMA on the ACIS program. There have been no items defined during the month that warranted generating a Contractor-Initiated ALERT.
The program continues to focus on flight hardware assembly and testing, with emphasis on performing to the PSMC schedule, and on resolving day to day situations to maintain that schedule. Problems encountered during the month were primarily associated with correction of minor fabrication anomalies identified as a part of normal test and checkout. Schedule critical milestones were met this month so there was no critical path schedule erosion.
Group B and C electrical testing of the 1N6689s and 15CGQ100s was put on hold pending assembly of the flight and spare PSMC Circuit Card Assemblies. Due to the relatively small residual lot sample sizes, after the flight CCAs are assembled, we will likely be able to provide some additional quantities to DPA Labs for the Group B and C testing and obtain improved test statistics.
Expedited procurement of the PSMC machined details was completed this month. All machined details have been received in time for the box mechanical part machining to be completing in time to support box-level assembly and testing of the flight PSMC. Assembly of survival heaters and thermistors to lid #1 has been initiated, with completion expected early in the next reporting period. Lid #1 must be sent through bonding and assembly operations to add survival heaters. Final box level assembly and testing cannot occur without this fully assembled lid. However, considerable preliminary testing can be performed using the "bare" lid.
Because of the late DPA/DEA Power Supply PWB completion (owing to residual delays in receiving the final EEE parts), these boards will not experience a post-conformal coat bakeout prior to flight unit assembly. All PWB assemblies will still receive a pre-conformal coat bakeout, as per initial plans. It is now planned that the DPA/DEA Power Supply PWBs will receive an "open box" prebake prior to formal 1238 bake processing at a point in the schedule that will not cause a delay in the critical path. This prebake will only entail lid removal (with no disturbance to electrical connections) to facilitate contaminant species depletion. A box functional test is planned after reclosing the lid and continuing with nominal flight unit processing.
Other progress includes:
Testing, conformal coating, and prebake of the Detector Housing Thermal Controller (DHTC) are now complete.
Testing, conformal coating, and prebake of the Serial Digital telemetry circuit card assemblies are now complete.
Testing, conformal coating, and prebake of the Vent Valve and Mechanism Controller PWBs are now complete.
Testing, conformal coating, and prebake the IO/EMI assembly are now complete.
Testing and conformal coating of the DEA Power Supply PWB assemblies are complete.
Testing and conformal coating of the DPA Power Supply assemblies are complete.
Testing, conformal coating, and prebake of the Motherboard are complete.
The PSMC test rack, including the RCTU Approximator (RAPP), has completed its flight interface design updates, checkouts, and quality-witnessed certification tests.
Open box testing of the flight PSMC assembly is in process. Box-level performance and functional test procedures for the PSMC have been updated for flight effectivity and forwarded to MIT for review.
PSMC Random Vibration and Thermal Cycling test procedures have been distributed for review and comment within LMA, to MIT, and to MSFC (as applicable).
There are no changes to the MIT load table during this reporting period.
The Detector Housing assembly is currently in storage until it is required by MIT for focal plane installation. Fitchecks were performed on the detector housing with the MIT provided Proton Shields and the DA MLI blanket.
The Engineering Unit Detector Housing was upgraded to the flight configuration this month. All operating/bakeout heaters, thermistors, connectors, and pressure transducers were installed onto the detector. In addition, the CAMSIM Starsys actuator was installed in place of the EU actuator since it is also in the flight configuration. The DH was performance-tested to verify that it was wired up the same as the flight unit. The EU2 PSMC was then used to open and close the door on both the A and B sides. A slight modification to the EU cables was required to get them to the flight configuration to allow operation of the actuators. Bakeout mode and normal operating mode were not verified at this time but will be verified in November.
The EU radiator assembly was delivered to MIT in the flight radiator shipping and storage container. The radiators were used in the fitcheck and tipper cart dry run which was performed at Lincoln Labs. The FU radiator assembly is in storage in the RDL, Class 100 cleanroom. All other TCS hardware except the shades have been 1238 certified and will remain in storage until needed. The shades are due to be 1238 certified at Ball Aerospace in early November.
Stress analysis updates will be performed in November and December with the completion of the fracture analysis to follow. The PSMC Vibration Test procedure was completed and passed on to MIT for review and forward to MSFC. Once the PSMC testing is complete, full attention can be spent on completing the final documentation of all stress and fracture analyses.
The SIMSim was fitchecked with the tipper cart at Lincoln Labs. No problems were encountered. The G-10 spacers (to replace the nylon) are due to be delivered at the end of this month.
Flight OBF acoustic testing started on the new Polyamide filters. Two sets of filters have been received and tested. One spectrometer filter was damaged during change out of the captive screws. It was sent back to Luxel and a replacement filter is being fabricated. Future filters will have all captive screws already installed to minimize handling of the filters and the risk of further damage.
The 200-cycle thermal cycle test was completed on both the Polyamide and Lexan Engineering Unit filters. There were 25 cycles between -61C and +50C, 25 cycles between -76C and +40C, and 150 cycles between -61C and +28C. After the testing was completed, the filters were sent to Luxel for post-test inspections. The post-test inspections showed no changes in the Polyamide filters. However, the Lexan filters did have some changes between pre- and post-test condition. The Imaging Filter had a very large pin window which changed to a very large pin hole. The Spectrometry Filter has an additional very large pin window (possible crack), a large crack at the edge, and a very tiny pin hole that were not present during pre-test inspections.
PTS Weight Summary is shown in Table 1. These values represent the best estimate of LMA-supplied components with an allocation of weight uncertainty. Some modifications have been made to the table as flight components are completed. Uncertainty margins will be reduced as measured data becomes available.
|Assembly||Weight, lb.||Uncertainty, lb.|
|Thermal Control & Isolation||5.4||+0.0|
|Sun & Telescope Shades||16.0||+0.0|
|Power Supply & Mechanisms Controller||32.7 (+.60)**||0.0|
|Cables & Connectors||9.5||+1.5 -0.0|
|Total Basic Weight||103.3||+1.5|
Note: Numbers in bold indicate actual measurements. Numbers in parentheses indicate changes from last month.
** Includes Survival Heaters, Thermistors, connectors, and bracket which are not part of ACIS budget. Mark Kilpatrick's (BECD) worksheet dated 12/8/95 assumed 1 pound for these components. LMA does not have an actual breakdown.
The Flight Venting Subsystem was successfully MSFC-SPEC-1238 certified. Once the flow restrictor performance has been verified with VGSE #2, the venting subsystem will be complete and ready for delivery. Currently this is scheduled for December 6, 1996.
An engineering unit venting subsystem was assembled from EU parts and is undergoing final testing. This EU subsystem will ship the beginning of November after final tests are complete.
VGSE #1 has been tested and is awaiting final assembly of some items for full computability. VGSE#1 is expected to ship the second week of November, in keeping with the priorities of Change Order 58. VGSE#2 work has been postponed while VGSE#1 was in final assembly and test. Once VGSE#1 is finished, VGSE #2 will go through final assembly and test for delivery.
The lifting fixture design, fabrication, and test are complete. The modifications asked for by BASD are in design. The expected design completion date is the middle of next month. The modified assemblies will be manufactured for installation on the lifting fixture sometime in 1997 prior to shipment to BASD.
The systems engineering group continued with the preparation of verification analyses reports, monitoring the systems design for compatibility with interfacing hardware, and engineering specialties support of the flight build activities during the October reporting period. Preparation of verification reports is an ongoing activity. These reports will document verification accomplished by test, analyses, demonstration and/ or inspections. Support of flight hardware fabrication, assembly and test remained the primary focus for Systems Engineering during October.
Update of the GSE to ACIS and Facilities ICD was completed during this reporting period. Revision F of 36-03020.02 ACIS Wire List was initiated. This revision is expected to be released early in the next reporting period.
Systems Engineering and Thermal/Mechanical Engineering supported the ISIM Delta CDA held at Ball Aerospace in Boulder, Colorado, on the 15th through the 17th of October. This was an informative review with a good exchange of information between MSFC personnel and those designing, fabricating and testing flight hardware. Ball Aerospace provided a copy of the ISIM fitcheck videotape prepared for the CDA which helps to understand the intricacies of integration issues and also helps derive answers to those issues.
Development of ACIS System Schematics continued during this reporting period. Because of the emphasis on fabrication and testing of flight hardware, the completion date for this task was rescheduled. This task is now projected for completion in the first quarter of next year.
Compatibility analyses of PSMC electrical interfaces with other ACIS, ISIM and Spacecraft hardware were completed. All identified incompatibilities within ACIS have been corrected. No incompatibilities were identified for ISIM or Spacecraft interfaces.
An LMA internal PIE Mission Success Review of the Thermal Control Subsystem was successfully completed. This review resulted in one minor action item and no open items were identified. The action item related to a particle emission question from the drilled venting holes in edge bonding materials of shades and radiators. A response to this action is pending. The Thermal Control Subsystem is ready for integration at the next higher level, and is certified to be compliant with its requirements. The next Mission Success PIE review is of the venting Subsystem and is scheduled to occur in December.
System-level overview and support of program scheduling and update of the ground processing flows for testing of ACIS instrument flight hardware continued throughout this reporting period. The ACIS component and system-level test flows are continuing to be maintained. A final update of the ACIS Verification Requirements and Specification Document SVR02 was not completed as expected and is now scheduled for completion during the next performance period. On-project reviews were supported and a liaison with MIT and NASA/MSFC for review, comment incorporation, and approval of formal verification test procedures was maintained.
Review of program activities and scheduling of the PTS and ACIS verification events continued throughout October. This activity, along with satisfactorily completing scheduled events, will confirm that the ACIS instrument meets requirements and will be ready for delivery to NASA/MSFC when needed.
Prebake and coordination of contamination control and MSFC-SPEC-1238 bakeout activities continued throughout this reporting period. This included monitoring drawing notes and processes to identify specific points in the manufacturing flows for vacuum baking of hardware. The telescope and sun shades were sent to Ball Aerospace for MSFC-SPEC-1238 certification during this reporting period. The chamber at Ball Aerospace required empty-chamber re-certification before the shades could be baked. The MSFC-SPEC-1238 certification is expected to be completed by mid-November.
Tests for interface compatibility between the PSMC and the RCTU were started during the September reporting period and the results were presented in last month's report. Attempts to checkout the Serial Digital telemetry and the Active and Passive Analog telemetry interfaces at that time were fraught with difficulties. These remaining untested interfaces are now scheduled to be performed during the next reporting period.
Component-level testing of the PSMC to RCTU Serial Digital Telemetry interfaces have not been completed. Further testing is planned to occur during the next reporting period.
The on-project review of the EU#2 EMI test report was completed during the previous reporting period. Incorporation of comments and release to the program did not occur as expected during this reporting period because of the focus on flight hardware fabrication and testing.
Planning efforts continued for the upcoming ACIS Instrument EMI/EMC testing. Currently, these tests are planned to commence in December of this year. The tests are expected to take 14 days to complete on 24-hour-a-day basis. Based on telephone and face-to-face conversations with MSFC personnel during this reporting period, the need to add an ESD radiated susceptibility test with the detector housing door open has been confirmed. Planning and definition of an acceptable test method for this test will occur during the next reporting period.
System Safety continued to support and monitor the program during this reporting period. Specific emphasis was placed on document/procedures review in support of upcoming system-level testing at LMA.
PMP engineering provided drawing review and redlines in support of drawings release, attended tabletop and drawing signature reviews, and continued tracking parts, materials and processes identification on MIT drawings.
The preparation and submittal of Program MUAs and support of MSFC-SPEC-1443 testing continued through this period. The last MUA for ACIS (MUA 003) will be submitted during the next reporting period. Because the MSFC-SPEC-1443 testing is not complete, not all MUAs submitted are approved; this effort did not finish as expected during this reporting period. This effort is now expected to continue at a low level through the December reporting period.
Working off additional comments received from MSFC about the ACIS FMEA was started via telecon with MIT. The additional comments are considered to be minor in nature and will be answered during the next reporting period.
The Power Summary Tables that summarize our current understanding of the power requirements have not changed since the June 1996 progress report. Therefore, these tables have been deleted from this report. For current Power Summary date refer to Progress Reports for June or July 1996.
Electrical power requirements (Watts) are summarized in the following table:
|Peak power distribution
in Standby Mode
|Peak power distribution
in Max. Operating Mode
|Peak power distribution
in Bakeout Mode
|Peak power distribution in
Normal Operating Mode*
Note: Normal operating mode refers to the ACIS operating with six analog chains at full power, six front-end processors at full power, one back-end processor at full power and the focal plane temperature being maintained at -120°C.