Monthly Newsletter

April 2001

SIM Status
First light tests for SIM have been conducted. Spectrum was measured through all focal plane diodes. Further study is ongoing concerning the focal properties of the spectrometer. Wavelength calibration performed well in the prism and diodes and a mercury spectrum was obtained. Scans on the mercury spectrum will be repeated to check for stray light and compared to SOLSTICE mercury scans, for accuracy. The CCD failure has been resolved by Goddard Space Flight Center. GSFC could not duplicate the failure, and a malfunctioning resistor may have been the initial cause failure. The suspect CCD has been demoted to a flight backup because of excessive handling. CCD boards are at an outside vendor for fabrication. ESR (electrical substitution radiometer) characterization is a bit behind schedule. The SIM ESR code needs test, the calibrator system is ready for assembly, the sunshade is at NCAR for fabrication. Internal harnessing is underway, and work is ongoing for the vacuum feedthroughs, internal bus board, and mechanism flight wiring. The vacuum door is ready for assembly. Final work on the kinematic mounts is underway, and housekeeping thermistors need to be added to the case.

SOLSTICE is well into testing. Flight instrument assembly and alignment are complete. LASP optical mechanical functional testing, LASP pre-environmental test calibration, and SURF Calibration #1 "A"is finished. Instrument (mechanical, optical, grating drive and detector assemblies) end-to-end testing is complete and the instrument performance meets or exceeds requirements on the bench. Thermal/vacuum test to test alignment stability is complete. Characterization, loose ends resolution, and adjustments continue.

XPS Status
Last month XPS was essentially built, except for testing. Environmental test and FOV (field of view), tests are now done. XPS/MU interface testing is underway. It seems that some investigative work is needed on the FPGA (flight programmable gate array) due to a nonperforming component. A JPL tiger team has been assembled to evaluate the part, and recommend resolution.

SORCE Systems Status
A MIWG (Mission Integration Working Group) was held April 4-5, 2001 at the Pegasus Rocket facility in Chandler, Arizona. It was determined that a Stage 3 camera is too expensive to implement on SORCE. The SORCE fairing and avionics deck are in house at the Chandler Rocket facility.

The instrument module harness is 90% routed and the instrument module MGSE (mechanical ground support equipment) cradle is being fabricated at NCAR (National Center for Atmospheric Research) and Zimmerman, an outside vendor, and the EGSE (electrical ground support equipment) rack is in use. The thermal XPS status analysis is complete pending internal review, and the TIM analysis is in process. The SORCE FMEA (failure mode and effects analysis), FTA (fault tree analysis) and PRA, (probability risk assessment) have been delivered to the Aerospace Corporation for review. The Aerospace Corporation is the parent body of the SORCE Red Team. OASIS-CC development end-to-end testing has resulted in the complete verification of command and telemetry functionality. XPS testing is complete on the flight instrument, TIM testing is in progress, SIM, SOLSTICE, and MU CSTOL scripts and procedures are 80% complete. Functional testing will follow after end-to end testing is complete. Module testing will follow functional testing. Additional requirements may become evident after the instrument functionals are complete. Power, mass and memory budgets are adequate, but instrument mass margin has been consumed. Measured values of power should be obtained in the near future, as well as mass measured values.

Recent accomplishments include the fabrication of a new bench (due to damaged laminate) and bearing cups (due to a tolerancing error) and the successful completion of the primary structure. The APE EDU (attitude power electronics engineering development unit) was tested with the box EGSE (electrical ground support equipment) and the unit was delivered to Flat Sat (test flat satellite). Twenty-five of thirty-two flight cards are complete. A successful Solar Array CDR was held and solar array substrates have been sent to SpectroLab for cell population. Shock test of the EDU fine sun sensor was successful following rework for prior test failure. RWE (reaction wheel electronics) vibration failure has been resolved and corrective action is underway. Orbital hosted a TIM (technical interface meeting) with LASP to review the SORCE bus integration and test schedule in light of structure delays. Orbital has reduced their thermal vacuum test schedule from 18 ½ cycles to 8 cycles to accommodate the late delivery of spacecraft components, and to meet I&T schedules. Flat Sat SDVF (software development and verification facility) is underway. Work has begun on the ECP (engineering change proposal) for spacecraft gyroless mode implementation.

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