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 September 1996.
There was no monthly status review for ACIS in September. As reported last month, the previous review had been on August 20; the subsequent review was conducted on October 3 at LMA. However, ACIS did participate in the AXAF Quarterly Review at MSFC on September 12 with both the Project Manager and the Principle Investigator in attendance. Additional meetings were held with the AXAF Project Office that morning concerning OBF testing for contamination and a general schedule review late in the afternoon
The ACIS schedule is still dominated by the refurbishment of the CCDs, which is turn is predicated on obtaining flexprints that can undergo the thermal cycling expected on orbit. As discussed below, the second set of flexprints from Speedy Circuits were found to have a fabrication flaw and only one unit survived incoming inspection at Lincoln Lab. This one unit was successfully installed on a flight CCD and delivered to CSR on September 27.
As reported last month, lot 2 flexprints from Speedy Circuits had about 18 units available as flight candidates. However, at about 150 cycles one of the flexprints failed. An analysis of the failed unit showed that a trace was open (not a failed via). The failure was the result of the Speedy Circuit technician cutting off the "pouch" (which protects the flexible portion of the rigid-flex during the final drilling and plating operations on the rigid ends of the flexprint) with a scalpel. Further careful inspection of the `flight' units showed this failure mode on 17 of the 18 candidates. Hence, only one unit survived to be installed on a flight CCD. However, on the positive side, by the end of September, no vias had failed with about 200 cycles on four of the lot 2 samples and smaller numbers on several other lot samples. Clearly, the re-design of the flexprints has overcome the problem with failures of the vias during thermal cycling.
Given the cut trace problem described above, Speedy immediately began yet another lot of flexprints. This lot was divided into two subsets (A and B). Lot 3A was completed be 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 is due for delivery in the second week of October.
In the meantime, Speedy Circuits seems to have overcome materials problems with the fabrication of the `via-less' flexprints. A fourth lot was in preparation and also due for delivery in early October. A prototype unit had undergone approximately 250 cycles at Lincoln by the end of September.
As reported above, the only flight flexprint from lot 2 was installed on a CCD, delivered to CSR, and is in calibration. To date, the unit appears to be as good a flight quality as any received in the spring. In addition, with the exception of two CCDs at Lincoln, all old flight CCDs have been calibrated at CSR and are awaiting new flexprints.
The following is a brief summary of the status of the other ACIS elements:
(a) A test was performed on a non-flight CCD flexed with a prototype `via-less' flexprint. This test was successful. The `via-less' design is acceptable to the science team.
(b) The DEA Analog Boards are still at Lockheed Sanders for conformal coating. Six units (out of 12) have been completed but the results are only marginally acceptable. A review was held at Sanders and it was found that no thinner had been used in the process. This resulted in a large number of `bubbles'. MIT had sent thinner to Sanders but it was mislaid. New thinner has been obtained and a test board coated successfully.
(c) The DPA printed circuit boards completed testing in September. The three BEPs were successful. However out of the eight FEPs, one had a failed `Mongoose' processor and two others had a one-time intermittent. The microprocessor has been removed (with much difficulty due to the thermal epoxy) and an engineering mongoose installed - the board then passed an electrical test. The units with an intermittent problem were each sent through six thermal cycles, but the intermittent did not re-appear. Plans were immediately put in place to load another four FEPs, and a random vibration test was conducted on one of the intermittent boards on September 30.
(d) The first set of the new OBFs was completed at Luxel and shipped to LMA for acoustics tests. This testing is scheduled for the first two weeks in October.
(e) The second lot of Rev B PCBs for the DEA Interface and Thermal Control were completed in September, but High Rel rejected these for the same reason as the first. Speedy Circuits challenged this rejection, and MIT contracted with GSFC/UNISYS to review all the coupons from this second lot. The Speedy Circuits and High Rel cross-sections were accumulated and sent to GSFC by the end of the month. In early October, we received a preliminary report that the coupons were acceptable as far as GSFC was concerned.
Due primarily to the delays in the receipt of flight quality flexprints, the ACIS schedule took a significant slip in September. Under the existing project plan, the ACIS delivery to XRCF slipped to mid April. However, MIT has proposed that the thermal vacuum test of the ACIS hardware be postponed to after XRCF. If this plan, is accepted by MSFC, the ACIS delivery to XRCF can still meet the March 15 need date.
Due to the uncertainty of the hardware schedule, as discussed above, no additional lay-offs were announced in September. However, lay-offs made earlier were allowed to go to completion. Three software engineers left the project on September 30, along with one of the contractor draftsmen. In addition, Bob Renshaw left the ACIS project on September 15, upon return from the last mockup TIM at BASD in early September. Due to the generation of a new set of translation table parameters by BASD/COI on September 19, and at the request of MSFC, the lay-off of Marty Furey was delayed from September 30 to October 14 (the last day legally possible).
Four CCDs were received; three of these had had Flextech flexprints replaced with Speedy Circuits flexprints of the standard design. Two of the latter three, w129c2r and w205c2r, had been previously calibrated at CSR, but were mechanically damaged during the "re-flexing" operation. The mechanical damage induced additional "dark current" in these devices, probably due to light emission near the damaged silicon surface. It was therefore not possible to determine accurately whether or not the re-flexing process changed the quantum efficiency of these devices. The third device to have been delivered after reflexing with the standard Speedy Circuits flexprint, w158c4r, had been screened but not calibrated at CSR before reflexing. This device functions well after reflexing. The reflexing operation appears to have caused only small (< 5%) changes in gain, and little or no change in noise. The standard calibration was begun on w158c4r. We have not yet received a well-functioning, previously calibrated, re-flexed device. This makes it impossible to determine completely the requirements for calibration of re-flexed devices.
Calibration resumed following last month's facility upgrades. We began calibration of four devices: w163c3, w168c2, w158c2 and w158c4r.
We supported calibration rehearsal with ACIS 2-chip (ACIS 2C) at the XRCF. What was intended to be the final ambient-pressure check of ACIS2C in the XRCF Instrument Chamber showed the instrument to be non-functional. A week of intensive effort, in which three of the four major ACIS2C subsystems were repaired or replaced (driver box, analog electronics and both CCDs) rendered the instrument functional. We also provided continuous support and coordination during the X-ray measurement phase of the calibration rehearsal. The only significant functional problem with ACIS2C during this phase concerned the liquid nitrogen supply system.
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.
Machining of the EMI gasket grooves in the Flight Unit +Y and -Y Panels is complete. This was much more difficult than anticipated.
The flight unit is being assembled.
The unit has been used for electrical testing with the DEA and DPA. It will be cooled by a chiller (see below). It will be up-graded to a more flight like configuration (heaters, thermistors and connectors) in late October.
A hoist has been modified and is being used with ACIS. The Tipper Cart has completed proof testing. Some minor enhancements are planned prior to a fit check of the SIM-Sim at Lincoln Labs. The SIM-Sim, built by LMA, has been received and looks very good. A chiller assembly has been built to cool the DA focal plane to permit better testing with the electronics. Initial tests indicate that it will work very well.
All printed wiring board designs are complete. During the workmanship vibration test of an FEP, the leads on two sides of both ACTELS fractured. The cause is under investigation.
The DPA internal cables, DEA internal cables and support structure cables have been drawn and released.
The PSMC mounting plate for the ACIS TV Test was designed to provide sufficient high-emittance area (Z306 black paint) for cold bias. Temperature control for the PSMC during the Test will be provided by a heater on the PSMC mounting plate and the survival heater on the top panel of the PSMC. The mounting plate heater was ordered and received from Minco in September.
The latest ISIM boundary conditions to be presented in the Delta CDA were received via TRW memo dated 8/29/96 and evaluated by MIT. They are more benign for DEA and DPA, hotter in the hot case for PSMC. MIT/LMA thermal engineers decided that the hotter environment indicates that the PSMC qualification temperature should be raised from 40°C to 46°C.
Measurements were made at the LL of the IR emittance of 2 DPA black panels, one before bakeout and one after bakeout at 120°C. Results show insignificant differences between the two, and good correlation with predicted values (prediction of > 0.84 vs. measurement of 0.86) for the Z306 black paint.
Review of the SIMSIM drawings by LMA revealed that 96 nylon spacers were specified. Because nylon can outgas at unacceptable levels, MIT requested that LMA order replacement spacers. LMA has ordered G10 spacers which are due to arrive in October.
An analysis was performed to assess the thermal impact to chip resistors and transistors on the DEA board during a fault condition with excess heat in those components.
The SIMSIM was received from LMA. Its thermal coatings and heaters were inspected visually and appeared satisfactory.
MIT participated in the Thermal TOP Telecon held on 9/12.
For this reporting period. the DEA engineering system continues to undergo intergration and performance evaluations. This process involves the full data and command handshaking with the DPA as well as the PSMC. Further, the test and evaluations are performed with the engineering unit RCTU and is driven by flight software.
Some flight unit conformally coated video cards have been completed. The flight backplane is also conformally coated. Flight system intergration will begin shortly.
The testing of flight BEPs and FEPs has been completed. Due to the intermittents appearing on two FEPs (see last month's status report), several FEPs were temperature cycled while running diagnostics. Neither failed as the ambient was varied from -40°C to +70°C several times. Still searching for the intermittent, one FEP was vibrated. This vibration test did turn up a problem: multiple leads on the two Actel ICs cracked quite obviously. An investigation regarding the cause of this failure, and whether it is related to the original intermittent opens, is ongoing.
The engineering DPA has been integrated with the Gulton RCTU emulator. Serial commands and telemetry both appear to function as planned.
The FEP power switch has been modified to ramp up in a slower and more consistent manner. This was done to correct a marginal incompatibility between the DPA and the PSMC.
Work on the DPA system level diagnostics continues. Most BEP tests run via the RCTU emulator now, and FEP tests are being adapted to run via a BEP resident monitor.
Wire lists for the PSMC-to-(L)RCTU thermal vacuum test harnesses have been updated. Wire list for the Data Logger harness is in progress.
Continued supporting integration tests of the modified RCTU engineering unit with the DPA and the PSMC.
Developed decommutation software for AXAF telemetry frames. This version only extracts the ACIS telemetry packet stream from the AXAF frames; it does not produce engineering or time stamp packets. Also developed a utility that produces a formatted, hexadecimal listing of AXAF minor frames. Began developing code that reads the telemetry format description file that the CTUE uses to construct AXAF telemetry frames. This code will contribute to decommutating the engineering telemetry items.
Supported the checkout of the RCTU Engineering Model and the PSMC. During this it was discovered that TRW did not have a complete list of ACIS high level pulse commands. Re-sent the complete command, telemetry and structure information to TRW.
Discovered that the CTUE was not transmitting minor frame 0 to the ACIS EGSE workstation. Also realized that the CTUE software is hard coded to place IRIG-B time stamp into the locations that were to have been science header, which has been deleted. Participated in a telecon that resulted in designating the former science header area as an additional engineering telemetry field. It was assumed that it could be devoted to science data, but the inability to reprogram the CTUE makes this difficult to implement.
Reviewed ECOs relating to the following modules:
The sequence checker has been tested against a wide variety of timed- exposure and continuously clocked PRAM and SRAM loads.
Published revision 02 of the Software Test Tools Document (MIT 36-55001). Updated IP&CL Structures and Release Notes to reflect ECO-736.
Updated flight software and UNIX simulator code to reflect ECO 36-736. Added DEA sequence checking to the BEP. Added BEP hardware serial commands and PSMC high-level pulse commands to buildCmds, the ACIS command generator program.
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. The FEPs are reading pixel data from the image loaders, the MIT RCTU emulators are communicating with the BEPs and with Sun SPARCstations without any trouble. In one test, a BEP successfully commanded 6 DEAs and 6 FEPs to execute a timed-exposure science run. Testing also continues with the UNIX software that simulates BEP and FEP.
15 new software problem reports have been filed, and most have been closed out. A total of 10 problem reports are outstanding. These may be viewed at "http://acis.mit.edu/axaf/spr/". All software test tools have been updated to reflect the changes in ECO 36-736.
Having completed their tasks, Ann Davis, Rita Somigliana, and Dan Hanlon left the Project at the end of this reporting period.
As a result of discussions between MSFC and MIT, Rhonda Schrimsher (MSFC) spent a week at MIT to familiarize herself with the ACIS instrument. She and Bob Rowe (MSFC) will assist MIT in performing software verification tests.
Alerts : Ten (10) 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. None of the Alerts listed below impact the MIT ACIS design at this time.
|ALERT #||MSFC #||Part Number and Manufacturer||Part or Material Name|
HYBRID MOLDED, ER
|H6-A-96-01||6970||MIL-C-83513/03 & /04
THOMAS & BETTS INC.
|MICROCIR UIT, |
PCM CODE C
Removed the SIM from the shipping container from LMA for visual inspection .
Generated the following 6 kits:
|(a) FEP Flight||(36-30302)||4 kit Ser #10, #11, #12, & #13 .|
|(b) Thermal Control Board (A)||Eng (36-20202)||1 kit Ser #4|
|(c) Thermal Control Board (B)||Eng (36-20262)||1 kit Ser #4|
Updated the following complete kits:
|(a) Thermal Control Board (A)||Flt (36-20202)||2 kits Ser #1 & #2|
|(b) Thermal Control Board (B)||Flt (36-20262)||2 kits Ser #1 & #2|
Two (2) transistor part types have been sent to ATC for 100% screening of PIND and XRAY. In addition, a sample DPA will be performed on each part type.
Received results of six (6) Speedy Circuits rigid coupons from HI-REL cross section analysis on the Thermal Control/Interface board in the DEA. All six (6) coupons failed 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 sent to Diane Kolos at GSFC for referee. After the GSFC review, cross sections will be sent to Jim Blanche at MSFC for review.
|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|
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 were recently completed by MIT and 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, Rad Hard
|Relay, Latching, DPDT, 5A||4/4/96||4/22/96|
|Microcircuit, Logic, HC||4/4/96||4/22/96*|
|Diode, Rectifier, Schottky||4/4/96||4/22/96*|
|Transistor, Power Switching||4/4/96||4/22/96*|
|Resistor, Precision, Low TC||4/4/96||4/22/96|
|Magnetic Devices -
Transformers and Inductors
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.
Four new flight Optical Blocking Filters (OBFs) have been ordered from Luxel. The first set was shipped on 9/30/96 and two (2) more sets will be shipped by 10/4/96. The fourth set will be shipped on 10/ 11/96. The new OBFs will be polyimid instead of lexan.
Sent 6 Material Usage Agreements (MUAs) to MSFC.
TRW HR G16 which involves the LMA MGSE was updated and sent to John Elliott of TRW by B. Bond of LMA.
The MIT license to handle radioactive sources does not include Cm244. Have asked for a new license so that it can be sent to MSFC. (4th month this is a problem)
The following items were produced or worked on during the reporting period:
Developed 1 additional test procedure (Threshold) and 1 test script (BadPixel)
Modified software test environment tools to run with the changing hardware/software environment.
There were 16 new Software Problems Reports generated.
There has been no activity on the Performance Assurance and Safety (PAS) Plan. The PAS Plan in effect is revision B.
Ten beryllium frames were cleaned and vacuum baked.
Cleaned the completed DPA internal harnesses and they were put into the vacuum chamber on Friday 9-27.
The completed internal DEA harnesses were cleaned and vacuum baked.
Performed the MRB rework on two Flight Back planes and one Flight BEP. Epon 829 with Versamaid 140 epoxy was applied to the delaminated, damaged areas and then the PWAs were placed into a vacuum chamber.
The black expando sleeving, that contaminated the pre-bake chamber, was placed into a vacuum chamber, with a TQCM, to determine if the sleeving was acceptable after the pre-bake. The sleeving was found to be acceptable with the TQCM, at 10°C, measuring 9 Hz over an 18 hour period.
Various miscellaneous brackets were cleaned.
The aluminum shields, 36-30201.0402 were reworked per ECO 36-635.
Eight sets of connectors, 4 different types, for the possible rekit of the FEPs, were cleaned and vacuum baked.
Started to clean all the hardware in bench stock for kiting into the DEA and DPA final assembly.
Six polyethylene proton shields were returned to MIT for rework. The rework was completed and the shields were sent back to LMA for cleaning and 1238 certification.
Placed one conformal coated Flight Video board into the ATC chamber, to determine if pump down time would be longer with the number of bubbles in the conformal coat. The vacuum chamber only took an extra hour to pump down.
Built new cleanroom area for cleaning material.
Problems in obtaining high quality flexprints continue to dominate the
The replacement flexprints received August 12,1996 have been subjected to qualification level thermal cycling from -150°C to +60°C and several problems have appeared. Nine samples from two lots were prepared. After 57 cycles one sample had its back junction connection open up. This connection is made by bonding an exposed via on the bottom of the flexprint to a gold trace on the alumina substrate using electrically conducting epoxy. A failure analysis indicates that the open most likely occurred due to delamination of the epoxy from the gold trace on the alumina substrate. The flexprint via was intact and conducting to the appropriate trace on the flexprint circuit.
Because of this failure, a modification to the flexprint mounting procedure has been made. A redundant electrical path for the back junction connection has been added to guard against this failure mode. A small gold wire is now passed through the via and underneath the flexprint. One end is bonded directly to the alumina's gold trace and the other end is bonded to the top surface of the back junction via.
Two samples of this design have been prepared and subjected to 200 rapid thermal cycles (dunk in liquid nitrogen/air bake with hot air gun). Both back junctions were intact after this testing. In addition, 26 samples representing the bonding performed at both ends of the gold wire were subjected to this same testing without incident.
A second problem that was revealed by the slow thermal cycle testing has been attributed to workmanship defects. After 146 thermal cycles an open developed in one sample. Failure analysis indicates that it was caused by inadvertent damage from a trimming operation at initial fabrication. The flexible portion of each flexprint is covered with a protective layer (called an envelope) of Kapton that spans between the two rigid ends during all of the plating operations. Prior to final inspection and shipment, the vendor removes this envelope by use of a knife. Unfortunately, the cut extended through the envelope, through the outer layer of Kapton protecting the copper traces, and into the copper traces. Thermal cycling caused this partially cut trace to fail.
Subsequent inspections of the 18 candidate flight parts revealed that 17 parts had at least a score mark partially through the outer layer of the flexible portion. Any mark made by the trimming operation was considered cause for rejection of that part. Changes have been made at the vendor to prevent this defect from occurring again. The one defect-free part was successfully integrated with a flight quality detector.
The completion of more than 200 thermal cycles 0n 4-5 test units verifies that the change from acrylic to polyimide adhesives results in vias that can survive our thermal requirements. Not one via has failed to date whereas the previous materials had many vias failing in less than 20 thermal cycles. This testing has highlighted the need for high quality components so as to avoid introducing new failure modes. Our efforts t o obtain a good supply of defect-free circuits has focused on testing, failure analysis and frequent communications with the vendor.
As reported last month, Speedy Circuits had begun an additional lot of flexprints to make up for the low yield. This lot consists of 12 panels with each panel having 12 parts. Delivery was originally expected Sept. 26, 1996. However, the first 9 panels (moving together as a sub-lot) were rejected by Speedy Circuits when routine coupon inspection revealed copper plating folds. The remaining three panels will be fabricated with changes to the process to eliminate this problem. These parts are expected to be shipped October 9, 1996.
Slow thermal cycling has continued on a prototype of the alternate design flexprint which has the vias moved to the warm end of the flexprint (described in previous progress report and referred to as "vialess"). This test is intended to verify the flexprint to alumina attachment process and has completed 248 of the required 200 cycles to date.
Speedy Circuits has had continued difficulties fabricating the alternate design having all of the vias in the warm end of the flexprint. Testing by Speedy Circuits has revealed that the copper-Kapton adhesion strength of the Sheldahl material is insufficient for our application. They have switched to a Dupont material which is constructed with a different technology but is a one-for-one replacement for the Sheldahl material previously used. Flexprints using the Dupont material are expected to be delivered October 7, 1996.
Graphics Research has been awarded contracts for both styles of flexprints. The conventional design was originally expected to be complete by October 8, 1996 but is now expected to be complete October 18, 1996. The delay is due to a backlog in their production facility rather than technical problems with our job.
Several devices have received new flexprints and have been returned to campus for additional measurements and testing:
|158C4||this device was originally screened at CSR with the Flex Tech flexprints, but was not fully calibrated. We have replaced this flexprint with a flight-quality Speedy Circuits flex, and it looks good after testing at Lincoln. The device is under test at CSR, and the Sector D output is NOT the noisiest, as we would have expected from Flex tech parts.|
|205C2||this device was earlier calibrated at CSR. It was damaged during re-flexing with a non-flight standard Speedy flex. (The objective of this experiment was to learn the extent of recalibration which would be required when refurbishing previously calibrated parts with new flexprints). Static and dynamic testing after re-flexing indicated problems, with sector C saturated and sector D dead. However, it was sent to CSR anyway with the hope that since Sectors A and B were still operational the original calibration could be rechecked. CSR found that the damage was too extensive for a test of the calibration change during reflexing to be valid.|
|205C4||this is a non-flight device which developed shorts and bright columns in sector D after sawing. The goal of this experiment was to test the vialess design flexprint. After reflexing with a non-flight vialess flexprint, dynamic testing indicated many bright saturated columns in sector C, and sectors B and D had bright but non-saturated columns. Sent to CSR for further evaluation. Higher clock pickup was seen, but the noise was brought to acceptable levels by changing voltage levels of device operation.|
During this month Change Order 56 was received which definitized Change Order 46. Based on this action, only Change Orders 41 and 48 to the LMA contract remain to be definitized. The change in the program plans due to the delay in the planned delivery of the ACIS Instrument and several other specific task that will add scope to the contract were coordinated and a Statement of Work was prepared by MIT. An engineering estimate to perform these activities was requested by MIT and provide by LMA. It is anticipated that the change order will be initiated in early October 1996 to authorize the work defined. However, work is going forward to enable delivery of the flight ACIS instrument by a promise date of 15 March 1997.
There was no monthly ACIS NASA/MIT Monthly Status Review nor MIT/ LMA Technical Interchange meeting conducted this month. Both of these activities are planned for early October.
Major accomplishments for September included completion and shipment of the SIMsim and shipping container to MIT; completion of printed wiring board assembly for all of the PSMC flight boards and completion of board testing for all but two board types; completion of the 1238 Certification bake of the flight Detector Assembly and Venting Subsystem; completion of the acoustics test of engineering units of the new polyamide OBFs; an FMD valve tree was provided to MIT to enable safe pump down and repressurization of the EU Detector Assembly at MIT/CSR; completed dye penetrant inspection of MIT flight standoffs, and completed a fit check of the proton shields on the Flight Detector housing. In addition, support was provided by LMA to the ACIS Mockup fit check on the SIM mockup at Ball Aerospace and LMA supported the integration test and checkout of the RCTU with the EU#2 PSMC at MIT/CSR.
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 fabrication 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 the result of difficulty in getting flight parts from outside vendors to enable timely completion of the flight hardware. To assure the timely receipt of these parts on program, a senior member of the LMA ACIS staff has been tracking each outstanding part, expediting dock to stock, taking steps to expedite delivery of the parts to the program and facilitating assembly of the parts into the flight hardware.
Group A electrical screening of the 15CGQ100s was completed and these parts were assembled into the remaining PSMC flight PWBs.
Expedited procurement of the PSMC machined details is progressing in a manner that supports projected flight PSMC assembly dates. Several machined details have already been received, including the front connector panel which has been assembled into motherboard assembly. All remaining machined details are expected in the next reporting period.
In spite of the progress made this month, the box mechanical part machining activities may still represent the schedule limiting element enabling box-level assembly and testing of the fight PSMC. Lid #1 is needed to send through bonding and assembly operations to add survival heaters. Final box level assembly and testing can not occur without the fully assembled lid, although considerable preliminary testing can be performed using the "bare" lid. This continues to represent a concern as of the end of this reporting period.
Delays in receiving the final EEE parts have delayed final assembly, test, conformal coating, and bake out of the flight PWBs planned for earliest completion. This has caused all of the flight electronics to complete board-level activities at approximately the same time, rather than a waterfalled completion schedule.
Because of the late DPA/DEA Power Supply PWB completion, these boards will not experience a post conformal coat bake out prior to flight unit assembly. All PWB assemblies will still receive a pre-conformal coat bake out, 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 of the Detector Housing Thermal Controller (DHTC) is now complete and the unit is in prebake.
The Serial Digital telemetry circuit card assemblies are completely tested and conformal coated.
Testing of the Vent Valve and Mechanism Controller PWBs is now complete and in prebake.
The IO/EMI assembly is complete, fully tested, and in prebake.
The DEA Power Supply PWB assembly is complete, with testing in progress.
The DPA Power Supply PWBs were received, assembly is complete, with testing in progress.
The Motherboard was received, assembled to the front panel, checked out and is ready for prebake.
The PSMC test rack, including the RCTU Approximator (RAPP) has nearly completed its flight interface design updates, checkouts, and quality witnessed certification tests.
There are no changes to the MIT load table during this reporting period.
The completed piece part radiation test data is now being folded into final radiation analysis verification reports.
The final machining and match drilling of the shims is complete and the shims have been sent for precision cleaning. The detector housing was precision cleaned for the final time and met the 100A requirements inside the camera body. The 1238 pre-bake and certification bake was also completed and the assembly is currently in storage until it is required by MIT for focal plane installation.
A radiator shipping container was completed for the warm/cold radiator assembly. All TCS hardware except the shades has been 1238 certified and will remain in storage until needed. The shades are due to be 1238 certified at Ball in late October.
No progress to report.
An update to the dynamic analysis was completed this month. Stress analysis updates will occur in October and November with the completion of the fracture analysis in December. With most of the hardware fabrication and testing now complete, full attention has been concentrated on completing the final documentation of all stress and dynamic analyses.
Proof testing and final cleaning was completed on the SIMsim. MIT has requested a change out of the Nylon spacers on the external panels to different material with lower out-gassing properties. New G-10 (glass epoxy) spacers were ordered and will be provided to MIT at a later date. The SIMsim was delivered to MIT for fit checks.
The suspect actuator from S/N 005 has been rebuilt, acceptance tested, and X-rayed prior to re-installation onto the mechanism. No anomalies were noted. The actuator was then installed onto the mechanism and actuator performance tests completed. X-rays will occur in early October to confirm that the O-rings are still properly seated. The MARS on this mechanism assembly will be kept open until all tests are completed and the unit is delivered back to LMA.
Vibration and Acoustic testing was completed on three different sets of EU Optical Blocking Filters (OBFs) this month. The tests were performed to: 1) Qualify a new Polyamide substrate or a thicker Lexan substrate, and 2) Determine the cause of several cracks and pin windows which were observed after testing of the old flight filters. Some of the old filter design were also re-tested in one case and tested for the first time in another. No new cracks or pin windows were observed on any of the OBFs after X-axis vibration testing. The same OBFs were then acoustic tested to Protoflight Levels and Qualification durations. The Polyamide filters did not show any new cracks or pin windows after testing; thus Qualifying the new design. The 2500 Angstrom Lexan filters did have cracks especially along the edge of the spectrometer filter where the frame interfaces with the Imaging filter frame. One of the old filter designs also had some small cracks. In conclusion, the acoustic test environment did cause cracks and pin windows to develop in the old 2000 Angstrom Lexan filters and the new 2500 Angstrom Lexan filters. However, the new 2000 Angstrom Polyamide filters did not develop pin windows or cracks.
An additional test was performed on a 2000 Angstrom Lexan spectrometer filter to determine if the Detector Assembly manual pump-down and re-pressurization could have caused the cracks. To simulate a worst case pump-down rate, the detector was evacuated at about 20 torr per minute. The re-pressurization was performed by instantaneously opening the low conductance vent valve full open. The Detector initially re-pressurized at about 37 torr per minute. The high conductance vent valve was then opened to maintain a 30 torr per minute ramp rate. It was estimated that there was about a 0.5 torr pressure differential across the filter. Post test inspections at Luxel did not show any new cracks or pin windows verifying that the pump-down and re-pressurization of the Detector did not cause cracks and pin windows to develop.
A PTS Weight Summary was provided to MIT and has been incorporated into Section 3.0 of this report. 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.
The Venting Subsystem has been 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.
The VGSE #2 has been assembled and is undergoing firmware upgrade and functional testing. This will be completed in the first half of October. Once this is done, the VGSE will also be ready to ship.
VGSE #1 update to VGSE #2 configuration has begun. The electrical portion of this update will be completed near the end of October. However, cleaning of the vacuum components to be compatible with the flight Detector Assembly will be delayed until the completion of testing with the EU Detector Assembly.
The lifting fixture is complete in the basic configuration, has passed proof load testing and has been cleaned for use with flight hardware. However, incorporation of the modifications requested by BASD as a result of the mockup fit check, and authorized by Change Order 43, to aid in assembly of the ACIS onto the ISIM were delayed in September due to flight hardware priorities and non-availability of a suitable off-program design engineer. Design for these modifications is scheduled to begin in early October.
Prebake and coordination of contamination control and 1238 bakeout 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. Baking of the Detector Housing and the Venting Subsystem was completed this month.
The TCS Shades are awaiting a baking oven at Ball Aerospace in Boulder, Colorado. This activity is planned for completion during the next reporting.
Tests for interface compatibility between the PSMC and the RCTU were started during this reporting period. These tests, conducted at MIT using the EU#2 PSMC, concentrated on the High Level Pulse (HLP) commands from the RCTU to the PSMC. There are a total of 136 HLP commands (68 A side and 68 B side) from the RCTU to the PSMC to control enable/disable and on/off functions. Each command was verified by monitoring the PSMC for the proper command recognition and response. Every command was exercised and every command was verified to result in a correct PSMC response. Attempts to checkout the Serial Digital telemetry and the Active and Passive Analog telemetry interfaces were initiated but not completed. These interface tests are expected to be completed during the next reporting period.
The on-project review of the EU#2 EMI test report were completed. Incorporation of comments and release to the program is expected during the next reporting period.
Planning efforts were initiate for the upcoming instrument level system EMI/EMC testing. Currently these tests are planned to commence in November of this year. The tests are expected to take 10 to 14 days to complete on a two 12 hour shift basis. Based on telephone conversations with MSFC and MIT during this reporting period, it is anticipated that some of the required tests may be reduced or limited in scope to accommodate the addition of a ESD radiated susceptibility test with the detector housing door open.
Continued to support the ACIS program during this reporting period. Beginning activities to support upcoming system level testing at LMA.
PMP engineering provided drawing review and redlines in support of drawings release and attended table top and drawing signature reviews. Tracking of parts, materials and processes identification on MIT drawings was also continued.
The preparation and submittal of Program MUA's and support of MSFC-SPEC-1443 testing continued through this period. This effort is expected to be completed during the next reporting period.
Incorporation of the final comments into the ACIS FMEA was completed. This document was released to MIT this month.
The systems engineering group continued with the preparation of verification analyses reports monitoring of the systems design, for compatibility with interfacing hardware, and engineering specialties activities in support of the flight build schedule. Preparation of verification reports is an on-going activity. These reports will document verification accomplished by test, analyses, demonstration and/or inspections.
Support of flight hardware fabrication, assembly and test remains the primary focus during September. Chamber operation and contamination control leading to the completion of MSFC SPEC-1238 baking of the flight Detector Housing, Venting Subsystem and Thermal Control System were performed.
Update of the GSE to ACIS and Facilities ICD is scheduled for completion early in the next reporting period. Comments were received for this document and are being incorporated. This is the last of the requirements documents needing update.
Development of ACIS System Schematics continued during this reporting period. This task is projected for completion in October.
Mission Success PIE review of the Flight Detector Housing was successfully completed during this reporting period. This review resulted in no action items and no open items were identified. The Flight Detector Housing is ready for integration at the next higher level, and is certified to be compliant with it's requirements. The next Mission Success PIE review is of the Thermal Control Subsystem (TCS) and is scheduled to occur during the next reporting period.
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. ACIS component and system level test flows continued to be maintained. A final update of the ACIS Verification Requirements and Specification Document SVR02 is scheduled for completion during the next performance period. On-project reviews were supported and 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 September. 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 as required.
Schedule remains the most significant management problem.
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.