WEEKLY HIGHLIGHTS FOR WEEK ENDING 25 July 1997:
Paul Ehrensberger and his team have completed an important test of the Telescope Readout Electronics (TRE). The Engineering Unit (EU) Forward Electronics and EU Detector Electronics exhibit dark current of less than 80 electrons/second and the differential current (between the two bi-cells) is less than 15 electrons/second. These numbers are end-to-end measurements made under standard laboratory conditions. The implication of absolute numbers this low is that the stability requirement of 5 electrons/second equivalent can be easily achieved with this design. The Flight Unit Detector circuits (Sapphire Carriers) are being produced at GSFC with 9 delivered to date, and the Forward Electronic PCB schematics and layouts have been released.
Four Telescope Readout Electronics (TRE) flight circuits on sapphire carriers have gone through initial screening and testing. Electrical characterization of the circuits and measurements of the leakage current at 77 K were made. None of the 32 Goddard JFETs has failed.
The Top Hat for Probe-C was delivered to LMMS on 11 July, concluding the procurement of one of the Probe's major pieces of hardware. The gold-plated, stainless steel assembly has over 70 feed-thru connectors welded into it and provides all the interfaces from inside the Probe to the outside electronics. It arrived just in time for in-house processing (including leak checks and cleaning) prior to mounting to the Probe assembly.
Mission Support Software Build 1.7 to support Experiment Control Unit (ECU) operations in GTU-2 Payload Testing has been completed and is being integrated with the ECU in the Integrated Test facility in building 251. The Build 1.7 acceptance review is planned for 7/31/97. The Flight Computer memory and CPU estimates have been completed and will be presented at the upcoming Program Monthly Review.