1. GLAST LAT ProjectDOE/NASA Peer Critical Design Review, March 19-20, 2003 G. Haller 4.1.7 Monitoring V6 1 GLAST Large Area Telescope: Electronics, Data Acquisition & Instrument Flight Software Monitoring & Thermal Control Gunther Haller Stanford Linear Accelerator Center Manager, Electronics, DAQ & FSW LAT Chief Electronics Engineer haller@slac.stanford.edu (650) 926-4257 Gamma-ray Large Area Space Telescope

2. GLAST LAT ProjectDOE/NASA Peer Critical Design Review, March 19-20, 2003 G. Haller 4.1.7 Monitoring V6 2 Monitoring & Thermal Control Outline Overview Temperature Monitoring (Matrix) Voltage/Current Monitoring (Matrix) Operating Temperature Control Survival Summary

3. GLAST LAT ProjectDOE/NASA Peer Critical Design Review, March 19-20, 2003 G. Haller 4.1.7 Monitoring V6 3 Monitoring Spacecraft monitors –Voltages & Temperatures PDU SIU GASU VCHP switches –Temperatures Locations outside LAT EMI shield PDU monitors –Voltages & Temperatures TEM EPU SIU –Temperatures Locations outside LAT EMI shield GASU monitors –Voltages & Temperatures ACD TEM monitors –Voltages & Temperatures CAL TKR

4. GLAST LAT ProjectDOE/NASA Peer Critical Design Review, March 19-20, 2003 G. Haller 4.1.7 Monitoring V6 4 Temperature Monitoring (SC & PDU) NameTypeSpacecraftPDU PrimeRedundantPrime Redundan t ACD TilesThermal55 ACD TSA Shell (inside)Thermal55 ACD TSA Shell (outside)Thermal 22 ACD BEA-Grid interfaceThermal 22 ACD PMT RailThermal4444 Calorimeter BaseplateThermal 16 SIUThermal22 PDUThermal22 EPUThermal 33 GASUThermal22 TEM DAQ BoardThermal 16 TEM pwr SupplyThermal 16 Radiator Anti-Freeze HtrThermal 44 RadiatorsThermal8810 Grid-Radiator interfaceThermal4444 Grid Make-up HeatersThermal44 VCHP-XLHP interfaceThermal4412 X-LAT PlateThermal44 VCHP-DSHP interfaceThermal 12 GridThermal 12 VCHP's Reservoir HtrThermal12 24 VCHP Reservoir Htr Pri/SecVoltage44 Spare Temp. ChannelsThermal88

5. GLAST LAT ProjectDOE/NASA Peer Critical Design Review, March 19-20, 2003 G. Haller 4.1.7 Monitoring V6 5 Temperature Monitoring (TEM & GASU) NameTypeTEMGASU PrimeRedundant ACD FREEThermal 12 CAL AFEEThermal128 AEM Power SupplyThermal 11 AEM DAQ BoardThermal 11 TKR CablesThermal256 LAT Instrumentation Plan: LAT-SS-00890 Spacecraft ICD: GSFC-IRD-433

6. GLAST LAT ProjectDOE/NASA Peer Critical Design Review, March 19-20, 2003 G. Haller 4.1.7 Monitoring V6 6 Voltage/Current Monitoring NameTypeSpacecraftPDUTEMGASU PrimeRedundantPrimeRedundant VCHP Reservoir Htr Pri/SecVoltage44 SIU Pri/Sec 3.3/5V VVoltage22 PDU Pri/Sec 3.3V VVoltage22 GASU Pri/Sec 3.3/28V/3.3VA VVoltage22 66 EPU 3.3V VVoltage 44 TEM 3.3V VVoltage 16 ACD FREE VVoltage 12 ACD FREE ICurrent 11 ACD HV (I)Current 24 TKR VVoltage 64 TKR ICurrent 64 CAL VVoltage 48 CAL ICurrent 48 TEM DAQ VVoltage 16 TEM DAQ ICurrent 16 LAT SIU Bus V Pri/SecVoltage22 LAT VCHP Bus V Pri/SecVoltage22 Spare Voltage ChannelsVoltage18 Total 32 20 25643

7. GLAST LAT ProjectDOE/NASA Peer Critical Design Review, March 19-20, 2003 G. Haller 4.1.7 Monitoring V6 7 Heater Control Survival Heaters (GRID & VCHP Anti-Freeze) –Powered by SC unregulated feed –Block redundant prime and redundant set –Thermostat control, not controlled by LAT electronics Survival & Operational Heaters (VCHP) –Powered by SC regulated feed –Block redundant prime and redundant set of 12 heaters –Controlled by LAT SIU Temperature monitoring Software algorithm in CPU 12 hardware switches in SIB Hardware watchdog to power heaters as default –Final responsibility of survival is by SC LAT-SS-00715 Thermal Control System ICD

8. GLAST LAT ProjectDOE/NASA Peer Critical Design Review, March 19-20, 2003 G. Haller 4.1.7 Monitoring V6 8 Instrument Protection Instrument Damage Protection Against LAT Hardware & Software Malfunction –Protection against high and low temperatures –Protection of ACD Photo-Multiplier Tubes (PMT’s) in South- Atlantic Anomaly (SAA) –Document: LAT-TD-01553

9. GLAST LAT ProjectDOE/NASA Peer Critical Design Review, March 19-20, 2003 G. Haller 4.1.7 Monitoring V6 9 High and Low Temperatures GRID/Anti-freeze heaters –turn on when T is below thermostats –no LAT active control VCHP heaters –LAT responsible for operational control Survival –if T too high or too low SC puts LAT into safe mode Turns-off LAT SIU and Main DAQ power

10. GLAST LAT ProjectDOE/NASA Peer Critical Design Review, March 19-20, 2003 G. Haller 4.1.7 Monitoring V6 10 ACD PMT Protection LAT turns down PMT high-voltage levels during SAA passage to protect PMT’s –SC SAA notification PMT’s are hardware protected within ACD in case of DAQ mishap –ACD HV supplies have built-in protection to limit current to PMT’s

11. GLAST LAT ProjectDOE/NASA Peer Critical Design Review, March 19-20, 2003 G. Haller 4.1.7 Monitoring V6 11 Summary Monitoring of temperatures, voltages, and currents defined Heater control defined Instrument protection tree documented –LAT DAQ does not have final responsibility to protect instrument from damage Responsibility of spacecraft