Monthly Newsletter

January 2001

SORCE is tentatively scheduling a Science Meeting July 9, 10, 11 2001 at the Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado. We would like feedback from SORCE Science Team Members on the proposed dates for the meeting. Please contact
Gary Rottman, Tom Woods, and Greg Kopp, attended an EOS IWG meeting in Ft. Lauderdale, Florida on January 30 to February 1.
The SORCE QED (Quarterly Executive Dialog) was held at LASP January 30, 2001, and resulted in a positive evaluation for SORCE.

SORCE January 2001 Project Summary
Visitors from TRW Corporation attended the SORCE January Monthly Review to obtain an overview of the SORCE experiment and the LASP working environment, in order to evaluate possible future joint endeavors with LASP.
The EOS SORCE mission is scheduled for a launch date of July 2002. The SORCE program is on schedule and within budget. No mission descopes are envisioned at this time.
The SORCE Red Team has been redefined, and the Aerospace Corporation will now assume the role. The Red Team will attend all major SORCE reviews and make recommendations to SORCE based on their observations. SORCE and the Aerospace Corporation met January 23-24 to develop SORCE FTA (fault tree analysis), FMEA (failure modes and effects analysis) and PRA (probability risk assessment) documents. The Aerospace Corporation was favorably impressed with the SORCE program's electrical engineering, design redundancy, and ability to acquire science data.
SORCE continues to closely monitor and adjust schedules for instrument fabrication to respond to changing priorities and availability of facilities during fabrication and test. There are currently two major delays to spacecraft development, one is the 3 to 6 week delay in the delivery of the instrument bench, and the other is a 2 to 4 month delay in the SORCE receiving transponder. SORCE Team Members attended the Alenia Transceiver Critical Design Review in early February and so far, the late delivery of the transceiver has not directly impacted the bus I & T schedule.
The SORCE budget contingency continues to be depleted, largely due to the high cost of parts and outside electronic board manufacture. To date, SORCE contingency has been able to accommodate these rising costs.
Schedule slack time in the SORCE program is an ongoing concern. SOLSTICE slack has dissipated, due to the late delivery of flight subassemblies. The calibration plan for SOLSTICE is undergoing reevaluation, and rescheduling may recover time. SIM schedule slack is also small. An effort is un-

derway to acquire additional calibration support for SIM. All aspects of SIM manufacture are monitored daily.
The overcrowding of test facilities for all SORCE instruments is a problem. SORCE has scheduled testing facilities at Ball Aerospace, reworked testing schedules and purchased additional bench test equipment in order to alleviate this situation.
The question of IFOG (gyros) for the spacecraft is still an issue. The IFOG manufacture and reliability has been considered a risk to mission success. Orbital has constructed a study to determine ACS control system performance in the absence of IFOGs. It appears that the SORCE spacecraft could still fly with the ACS system if the IFOGs failed or were removed from the spacecraft.
Mass models of SIM, SOLSTICE A and B, and TIM have been shipped to Orbital.

TIM Status
Excellent progress has been made on TIM. All TIM parts are at LASP except for the kinematic mounts. TIM apertures are flyable, but measurements do not yet have an absolute accuracy of 25 ppm. Continued work on stray light scattering and internal reflections is ongoing.

SIM Status
SIM is being readied for flight build and will require 8 weeks for completion. A build plan has been devised and partial assembly and testing has begun.

The SOLSTICE instrument is also in the processes of integration, calibration and testing. Mechanical/optical integration is complete and imaging performance meets or exceeds requirements. Flight detector integration and GCI integration is finished. Flight grating drive shortterm repeatability and accuracy exceed requirements, but the grating drive exhibits sensitivity to external disturbances, and fixes are under consideration.

SORCE Data System Status
SORCE database traceability and reproducibility model has been completed. The managed data product software layer is nearly completed, and is now being used by other programmers as the basis for developing data product code. The Java Database interface layer has been enhanced in the last month, and is now utilized for algorithm development. The direct IDL interface of the Sybase database is complete and in the maintenance cycle. Telemetry ingest is undergoing initial testing. The conversion of SOLSTICE algorithms from UARS is almost finished. Ancillary services development is nearly done. SORCE has ongoing monthly telecons with ESDIS (Earth Science Data and Information System). The Memo-randum of Understanding between SORCE and

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