Monthly Newsletter

June 2001

Risk scenarios are under development to plan for any conse-quences that could develop from the potential launch overlap.

9. A problem was discovered in the Interpoint 5V flight power converters. The converters deliver a 10V transient power spike at instrument turn on. This power spike may harm sensi-tive instrument electronic components. The faulty flight power converters seem to originate in a single manufacturer's lot. Flight power converters are long lead items to purchase and replacement could impact all instrument build schedules. GSFC is helping to evaluate the faulty parts, and the quoting and purchase of replacement parts is underway. The converter problem must be fully defined, affected parts must be identi-fied, damaged and new parts must be tested, and, if necessary, replacement parts must be installed. This could prove to be a lengthy process. The faulty parts may have damaged SOL-STICE A and B, and the XPS instrument electronics.

Instrument Status
XPS is totally assembled and awaiting the outcome of the FPGA analysis. Faulty Interpoint 5V fight power converters may have affected XPS electronics. The instrument will un-dergo evaluation to determine the impact of the Interpoint 5v flight power converter to its functioning.
The TIM instrument parts are 99% complete and all tests ex-cept environmental test have been completed. The faulty flight power converters did not affect TIM, because they had not yet been placed in TIM equipment. Further TIM testing may be delayed until different flight converters can be pur-chased, or a decision is made regarding the use of Interpoint 5v flight converters from a different lot. New TIM door mo-tors are arriving from Ball Aerospace. In addition, TIM vac-uum door seals must be perfected. New lubricants are being tested for superior sealing abilities, and a new and heavier door may be designed to replace the current TIM door, which bends under the pressure necessary to completely vacuum seal the door.

Tim Instrument

SIM mechanical parts are 98% fabricated. SIM electrical parts are 66% complete. The assembly of SIM is well under-way, and additional shifts may be added to meet assembly schedule demands.

SIM ESR Elictrical Substitution Radiometer

SOLSTICE A and B electrical parts are 96% complete and electrical parts are 90% complete. The SOLSTICE instrument is basically complete except for the Interpoint 5V flight con-verter

problem. Additional research on the functionality of the SOLSTICE g-tube has been completed.

SOLSTICE Instrument

Microprocessor Unit (MU) progress has been good. 75% of the mechanical parts are complete, and 55% of the electrical parts are complete. MU Software Coding is well underway. The SIM task is 50% complete and little work remains on the SOLSTICE, TIM and XPS. An estimated 44 days of work remains for the completion of all coding processes.
The MU to the GCI (Generic Channel Interface) harness in-stallation is complete. Final bonding should take place the week of June 26, 2001 and the integration with the EMU (En-gineering Microprocessor Unit) as well. LPT's (Limited Per-formance Testing) with TIM, SOLSTICE and XPS should fol-low.

Systems Status
Aerospace Corporation delivered the SORCE FMEA/FTA/PRA (Failure Modes and Effects Analysis, Fault Tree Analysis, and Probabilistic Risk Assessment) final re-sults. SORCE residual risks are acceptable. The minimum success probability is 93.2% at 1.5 years, and full mission suc-cess probability is 72.8% at 5 years. The most significant risk to the SORCE mission is the single string RAD 6000. The PRE (Power Regulator Electronics) shunt card is the most sig-nificant contributor of residual risk for the spacecraft bus.

MU and MUFSW Status
Overall progress has been good. The EMU has been fully in-tegrated and is in software testing. Simulations are in process to identify bugs and eliminate them. Most flight instrument boards are complete or nearly complete. Instrument interface testing will resume when the Interpoint 5V power converter problem has been resolved.
The GCI (Generic Channel Interface) command telemetry ac-cepts command and produces instrument and software status telemetry. The initial DSP loading is complete, but command and telemetry needs to be integrated. The MU analog/digital converter integration is complete and all PCIIO functionality is complete. RAD6000 exceptions and data can be trapped and recorded. Five days of PCIIO stress testing revealed bugs, PCIIO EEPROM read errors, and PCIIO command buffer bit flips. These problems were identified and isolated. A single hardware issue may be causing these glitches and the search for a common solution is underway. New CTSIM (Com-mand and Telemetry Simulators) hardware are experiencing functional difficulties. Ongoing work with the CTSIM vendor should bring the units to operational status soon enabling fur-ther test.
Despite tribulations, SORCE progress has advanced and we remain on schedule, and ready to circumvent setbacks with ef-fort and solutions.

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