Gamma-ray Large Area Space Telescope Project Overview GLAST Large Area Telescope: LAT Pre-Shipment Review W Neil JohnsonNaval Research Lab LAT Dpty PI for Instrument/Observatory Operations firstname.lastname@example.org(202) 767-6817
e– e+ Instrument Design: 4x4 modular array LAT measures direction and energy of incoming gamma rays Si Tracker pitch = 228 µm 880,000 channels 18 X-Y layers of silicon w/ tungsten foil converters (12 layers × 2.8% X0 + 4 layers × 19% X0 + 2 layers) Anti-Coincidence Detector Segmented scintillator tiles 0.9997 efficiency Mechanical Sys. (inc. Grid & Thermal Radiators) CsI Calorimeter Hodoscopic array 8.4 X0 8 × 12 bars of CsI 2.0 × 2.7 × 32.6 cm 3000 kg, 650 W (allocation) 1.75 m 1.75 m 1.0 m 20 MeV – 300 GeV Electronics, Data Acquisition, & Flight Software
LAT Status • LAT has completed its environmental test program • Currently being loaded into transport container for delivery to General Dynamics C4 – SASS. • No major failures or environmental susceptibilities were discovered. • No significant performance changes throughout the program • Performance over temperature is stable • LAT requirement verification sell off is in progress • 459 Requirements • 72% (329) verification reports submitted to mission office • 48% (219) reports accepted • LAT End Item Data Package (EIDP) is in progress
Principal Investigator P. Michelson Instrument Scientist S. Ritz Collaboration Science Team EPO L. Cominsky Senior Science Advisory Committee N. Gehrels LAT Operations Steering Committee N. Johnson, S. Ritz, Co-chairs Contract/subaward Management N. Christiansen Deputy Principal Investigator Science Operations S. Ritz Deputy Principal Investigator Instrument/ Observ. Operations N. Johnson LAT Advisors L. Klaisner D. Horn Instrument Science Performance S. Ritz, W. Atwood LAT Commissioner E. Grove ISOC R. Cameron K. Fouts Project Manager System Engineering P. Hascall Administration D. Viera Integration &Test K . Fouts (A) Project Controls L. Price Mission Assurance J. Cullinan Flight Software J Thayer LAT Organization Chart: to launch + 60 days
LAT Environmental Test FlowPlan and Performance PER Plan date in black System Commissioning/ System Test Shipment 5/14/06A 5/11/06 5/08/06A 3 days Actual date in red 5/20/06A Install Radiators Offload & Set-up LAT Sine Vibe EMI/EMC Test Acoustic Test CPT 5 days 5 days 9 days 11 days 7 days 6/14/06A 7/1/06A 6/24/06A 3 days PER 5/25/06A 7/10/05 7/05/06A 7/29/06A Remove Radiators T- Bal T- Cycle Pre TV CPT Pack and Ship Weight & CG 7/5/06A 9/12/06A 9/07/06A 3 days 2 days 2 days 2 days 9/15/06 9/18/06A Arrival SASS 43 days PSR 9/13/06 9/15/06A NOTE: Durations for moving and setup have been incorporated into the total duration for the test.
Issues / Liens to Delivery • Current LAT Flight Software does not meet all 183 requirements • LAT environmental testing performed with FSW B0.6.9 • Demonstrated 149 / 183 requirements • Over 1100 hrs of run time w/ B0.6.9 (over 1600 total hours) • Over 800 million events (mainly cosmic muons) processed. • Missing final event filters, data compression, GRB support • FSW B0.7.0 installation planned post ship to SASS • 173 / 183 requirements (all but on board GRB detection algorithm) • FQT of these 173 requirements has been completed on LAT test bed at SLAC. • FSW B1.0.0 installation prior to Observatory test. • 183 / 183 requirements • Unexpected reboots of LAT flight computers (SIU / EPU) • Observed 7 reboots in ~ 1600 hours of operations (3 CPUs operating at all times) • Probable root cause on about half indicate EGSE source • 1 hardware error – transient uncorrectable memory error • At least 2 (during TVAC) can not be explained by EGSE - watchdog
T- Bal T- Cycle Pre TV T- Bal T- Cycle Pre TV LAT Flow – Path Forward 9/16/06 Remove Radiators CPT Weight & CG Pack and Ship 7/05/06A 9/07/06 3 days 9/12/06 2 days 2 days 2 days 39 days PSR 9/15/06 9/28/06 9/18/06 9/23/06 10/01/06 CPT CPT CPT LAT Integration LAT FSW Install/Test Unpack LAT 8 days 3 days 3 days 1 day 2 days 3 days 12/15/06 Install Radiators CPT CPT Observatory EMI/EMC Acoustic Test Sine Vibe CPT Sep Shock Ship to Launch Site
Radiators Installed and Micrometeoroid shield exposed Prior to MLI blanket installation – exposed micrometeoroid shield
Installing the MLI Blankets Final LAT dressing – 2 tone MLI blankets Now, 102 uses for duct tape (actually Ge coated Kapton outer ACD MLI blanket)
Prep for TVAC Need to rotate from +Z vertical orientation to+X vertical orientation VCHP need to be horizontal to operate w/ gravity for TVAC
Thermal Test Equipment Sink plates w/ heaters simulate solar load on ACD and other components
Move to TVAC CALROD cages (toaster elements) simulate heat loads on radiators Trolley interfaces w/ rail system in TVAC chamber
LAT on Shipping Container Base Ready to Ship!