GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 8 of 12 Thermal Vacuum Test 1 GLAST Large Area Telescope LAT Pre-Shipment Review Thermal Vacuum Test Jesse Armiger Thermal Vacuum Test Director Stanford Linear Accelerator Center Gamma-ray Large Area Space Telescope

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 8 of 12 Thermal Vacuum Test 2 Agenda Test Overview and Major Test Event Log Compliance To Requirements Correlation Results Thermal Test Observations Summary

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 8 of 12 Thermal Vacuum Test 3 Test Picture

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 8 of 12 Thermal Vacuum Test 4 Test Overview

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 8 of 12 Thermal Vacuum Test 5 Compliance to Requirements LAT successfully completed Thermal Vacuum Testing –40 day test was successfully completed with only EGSE issues –Successfully tested LAT at Proto-Qual levels Verified thermal subsystem performance –Heaters –Heat pipes –Temperature sensors –Thermal Interface/Unit Mounting Thermal analysis correlation –No abnormal observations –Complete by October 30

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 8 of 12 Thermal Vacuum Test 6 Heater System Verification Survival heater system maintained all temperatures within limits during Survival Thermal Balance –Unregulated and regulated feeds at minimum voltage Unregulated feed at 25v and regulated feed at 27v –Grid heaters cycled at primary set points –Radiator Antifreeze heater duty cycle under review Demonstrated primary VCHP heaters could close Radiators at 70% power Functionally demonstrated all primary and redundant Radiator antifreeze and Grid heaters Demonstrated TCS could maintain RIT at all operational levels

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 8 of 12 Thermal Vacuum Test 7 Heat Pipes and Thermal Interfaces Heat Pipes –All Heat Pipes functioned normally DSHP and XLATs operated as expected VCHPs opened/closed Radiators as designed Interfaces –No baseplate outliers

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 8 of 12 Thermal Vacuum Test 8 Unit Temperature Distribution Hot Thermal Balance

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 8 of 12 Thermal Vacuum Test 9 Test results show good correlation between sink temperature predictions and input Watrod power ACD model received from GSFC uncorrelated – ACD MLI effectiveness needs evaluation ACD temperatures have impact on LAT correlation –Generally ACD tile temperatures higher than predictions (>5 o C) in all cases –Higher tile temperatures lead to higher tracker temperatures Grid heaters need to be modeled with individual thermostat set points for each circuit Preliminary Correlation 1/2

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 8 of 12 Thermal Vacuum Test 10 Hot Case - Temperatures generally lower than predicted Cold Case – –Temperatures generally higher than predicted –Radiator Anti-freeze and grid survival heaters off –VCHP heaters 9.7 watts to maintain RIT between -6 o C and -5 o C (23% duty cycle) Locked on to maintain RIT between -1 o C and 0 o C Survival Mode –Temperatures generally higher than predicted –Radiator Anti-freeze and grid survival heater use about 7 amps –Heater Power use higher than predicted Preliminary Correlation 2/2

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 8 of 12 Thermal Vacuum Test 11 Test Predictions vs. Actuals

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 8 of 12 Thermal Vacuum Test 12 ACD temperature sensor exceeded its red alarm limit of 40  C (unit proto-qual = 40  C) –This sensor reached a maximum of 42  C; the temperature excursion may have been caused by sensor malfunction –This was not unexpected because the ACD is bounded by a thermal blanket on one side and Tracker Towers with goal temperatures of  C –The ACD project manager has indicated that this temperature poses no risk to the ACD –Recommend an ACD red limit of 45  C for the observatory test Thermal Test Observations

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 8 of 12 Thermal Vacuum Test 13 LAT start up sequence from cold survival NCR #? –The normal start up sequence involves incrementally powering up the LAT in a manner which does not exceed the power budget –The planned sequence involved powering up the TCS last but it turned out that this step had to be performed earlier in order to stay within the budget –This minor change will be documented and implemented in the normal turn on sequence to be performed during observatory level testing Thermal Test Observations

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 8 of 12 Thermal Vacuum Test 14 The LAT thermal vacuum test was accomplished ahead of schedule and without any major incident. Three thermal balances (hot, cold and survival) and four thermal cycles were performed. Thermal data readout by VSC was very noisy and inaccurate; this caused hardship during the test. Minor incidents were corrected efficiently. Complete LAT Thermal Vacuum test report by October 31. –Include thermal model correlation Summary

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 8 of 12 Thermal Vacuum Test 15 Major Thermal Vacuum Test Events 1/2 Performance Testing

GLAST LAT Project September 15, 2006: Pre-Shipment Review Presentation 8 of 12 Thermal Vacuum Test 16 MajorThermal Vacuum Test Events 2/2 Thermal Cycling