GLAST LAT ProjectFace to Face, 14 April 2004 LAT System Engineering 1 GLAST Large Area Telescope: EGSE and Interface Verification Pat Hascall SLAC System Engineering Manager Gamma-ray Large Area Space Telescope

GLAST LAT ProjectFace to Face, 14 April 2004 LAT System Engineering 2 Overview Summary Approach EGSE Definition EGSE Verification requirements EGSE CM Flight Interface Verification

GLAST LAT ProjectFace to Face, 14 April 2004 LAT System Engineering 3 Summary EGSE must be tested (acceptance) to a released procedure prior to use with flight hardware –EGSE hardware/software must be documented and acceptance test to ensure that it will not damage flight hardware and that it performs intended functionality –EGSE hardware/software must be documented sufficiently to support fault isolation The acceptance testing includes flight hardware interface verification The testing includes software (scripts) The current approach is to have the user (Cal, Tracker and ACD) do interface verification and script verification

GLAST LAT ProjectFace to Face, 14 April 2004 LAT System Engineering 4 What is GSE? Any test equipment that interfaces with or touches flight hardware Includes boards used to test at lower levels of assembly Includes EGSE isolated by connector savers

GLAST LAT ProjectFace to Face, 14 April 2004 LAT System Engineering 5 EGSE Verification Requirements Performance Verification Plan (LAT-MD-00408, Rev 1) –Section 6.2 requires that EGSE be under configuration control with The hardware and software associated with Ground Support Equipment (GSE), which is used to test or verify design, engineering, mission requirements and specifications to flight hardware or software, will be under configuration control. All GSE hardware are considered configuration items (CIs) and will be built to released drawings and tested against released procedures. Test software and GSE firmware will be managed and controlled as released CIs and be subject to program release and configuration management practices. All GSE hardware, software and firmware will be subjected to acceptance tests before being placed into service. All GSE hardware, software and firmware will be subjected to validation tests prior to use in a specific configuration. The validation test will be repeated when the configuration is changed, external electrical interfaces are broken or other configurations are modified which compromises the previous validation test.

GLAST LAT ProjectFace to Face, 14 April 2004 LAT System Engineering 6 EGSE Verification Requirements (cont.) EGSE –All EGSE will be certified for use on flight hardware by means of a released test procedure. –EGSE will be subjected to acceptance test procedures when built and after any break of internal configuration. –EGSE will be subjected to validation tests after any break of electrical configuration and prior to first use in a configuration

GLAST LAT ProjectFace to Face, 14 April 2004 LAT System Engineering 7 Misc Configuration Management –The EGSE documents are considered level IV documents –Signoff is ELX and QA –Copies have been sent to affected subsystem managers Failure reporting –NCRs will be written for EGSE anomalies observed after initial acceptance of the EGSE

GLAST LAT ProjectFace to Face, 14 April 2004 LAT System Engineering 8 Current EGSE Testing The EGSE provided by ELX for Cal and Tracker is tested at SLAC using LAT-TD –This tests the combination of TEM, TEM Power Supply and test crate, and is the planned procedure for flight testing Verifies front end communications Verifies temperature monitor Verifies output voltage setablilty using built in telemetry (biases and fixed voltages) –Discussion The procedure does not test the interface to the level required by the Performance Verification Plan (see slide below) in that the electrical interface is not directly verified Level of functionality testing unclear (are paths through to the CAL and Tracker tested?)

GLAST LAT ProjectFace to Face, 14 April 2004 LAT System Engineering 9 Current EGSE Testing (continued) Separate procedure provided for checkout of EGSE prior to connecting to flight hardware (LAT-TD for Cal and LAT-TD for Tracker) –These procedures use Cal or Tracker scripts to validate the EGSE prior to use These tests are to include detailed interface verification –Discussion Problems at EGSE output connectors may not be found until after delivery to subsystems

GLAST LAT ProjectFace to Face, 14 April 2004 LAT System Engineering 10 Interface Verification Requirements From Performance Verification Plan ((LAT-MD-00408, Rev 1)) – Electrical Interface Tests Electrical interface tests are conducted to insure integrity of the electrical interfaces. Depending on the circumstances, one or more of the following tests will be performed: –Signal distribution –Power Distribution –Command Distribution –Grounding –Isolation –Insulation Resistance –Hi-Pot –7.3.1 Interface Verification Tests Interface verification tests will be performed on all subsystem electrical components prior to integration. Measurements will be made of all interface electrical signals. Grounding, isolation and insulation resistance (hi-pot) tests will be performed prior to connecting a new subsystem component to an integrated assembly. Electrical interface cables will be tested for continuity, impedance, isolation and insulation resistance (hipot) prior to integration with flight hardware. –Subsystem test matricies include interface verification

GLAST LAT ProjectFace to Face, 14 April 2004 LAT System Engineering 11 MAR Interface Test Requirements Electrical Interface Tests –Before the integration of a component or subsystem into the next higher hardware assembly, electrical interface tests will be performed to verify that all interface signals are within acceptable limits of applicable performance specifications. Prior to mating with other hardware, electrical harnessing will be tested to verify proper characteristics such as the routing of electrical signals, impedance, isolation, and overall workmanship.

GLAST LAT ProjectFace to Face, 14 April 2004 LAT System Engineering 12 Recommendations Strengthen TEM Test Procedure (LAT-TD-03415) to verify outputs at the interface to the CAL and Tracker and use this procedure for the EGSE used on the CAL and Tracker Use similar rigor for the GASU test stand CAL, Tracker, ACD and I&T continue to have the responsibility to verify the test scripts Test procedures for EGSE validation (LAT-TD for Cal and LAT-TD for Tracker) should be completed and maintained by Cal and Tracker to be tailored for use in the Subsystem test program