Philip Luers NASA/GSFC Code 561 August 16-17, 2005 Electrical Philip Luers NASA/GSFC Code 561 August 16-17, 2005

Electrical Systems Document Tree Mission Requirements Document (431-RQMT-000004) Electrical Systems Specification (431-SPEC-000008) Delta II PPG (MDC 00H0016) C&DH EICD (431-ICD-000141) General Thermal Subsystem Specification (431-SPEC-0000091) PSE EICD (431-ICD-000142) CRaTER EICD (431-ICD-000094) PDE EICD (431-ICD-000143) DLRE EICD (431-ICD-000095) Star Tracker EICD (431-ICD-000144) Power, 1553, SpaceWire, 1 pps, RS-422, Grounding, Isolation, Shielding, Charging LAMP EICD (431-ICD-000096) Inertial Meas. Unit EICD (431-ICD-000145) LEND EICD (431-ICD-000097) Communications EICD (431-ICD-000146) LOLA EICD (431-ICD-000098) Propulsion EICD (431-ICD-000147) LROC EICD (431-ICD-000099) Reaction Wheels EICD (431-ICD-000148) Heaters, Thermistors Gimbal Controller EICD (431-ICD-000149) Solar Array EICD (431-ICD-000150) Battery EICD (431-ICD-000151) Mini-RF EICD (431-ICD-000152) LRO SpaceWire Spec. (431-SPEC-000103) Electrical Systems Requirements Document (431-RQMT-000140) Specific Interfaces Connectors, pinouts Specific Interfaces Connectors, pinouts

Lunar Reconnaissance Orbiter (LRO) Electrical System Level 2 Flow Down Key Power Requirements Level 2 Req. Level 3: Requirements Concept/Compliance Paragraph Requirement MRD-32, MRD-101 ESR-1 The Electrical System (ES) shall distribute 28+/-7 VDC power to subsystems. Shielded twisted pair for 45 services. ESS-5 ESR-2 The ES shall provide the capability for redundant power and ground wires (more than required for each service). Easy implementation to protect against broken wires. ESS-35 – ESS-38, ESS-43 ESR-3 The ES shall implement a single point ground system, with appropriate primary power isolation Best practice for spacecraft primary power from NASA-HDBK-4001.

Lunar Reconnaissance Orbiter (LRO) Electrical System Level 2 Flow Down Key Grounding Requirements Level 2 Req. Level 3: Requirements Concept/Compliance Paragraph Requirement ESS-45, 47,48 ESR-4,5 The ES shall provide ground straps where necessary to ground all chassis and conductors. Best practice for charging avoidance per NASA-HDBK-4001 ESS-54, 63 ESR-6 Ground all harness shields. Best practice for controlling EMI/EMC. ESS-55, 56, 57, 59, 60, 61, 156-159, 167-173, 177-186 ESR-7 The ES shall ground all external surfaces. ESS-188 – ESS-193 ESR-8 The ES shall be designed to minimize internal charging. MRD-28, ESS-65 ESR-9 The ES shall be designed to minimize radiated emissions and radiated susceptibility to ensure Orbiter self-compatibility. Best practice for controlling EMI/EMC

Lunar Reconnaissance Orbiter (LRO) Electrical System Level 2 Flow Down Key Data Requirements Level 2 Req. Level 3: Requirements Concept/Compliance Paragraph Requirement MRD-36, ESS-102 ESR-10 The ES shall implement a SpaceWire network to support LROC and C&DH High speed bus harness and pinouts per ESA SpaceWire specification (ECSS-E-50-12) MRD-35, ESS-106, ESS-108 – ESS-115 ESR-11 The ES shall implement a dual redundant MIL-STD-1553 to support CRaTER, DLRE, LOLA, LEND, C&DH, IRW, IMU, ST, PSE, PDE, and Gimbal Controllers. To/from BC and RTs per Electrical Systems Specification (431-SPEC-000008) ESS-122 – ESS-126 ESR-12 The ES shall implement +5V discrete commands with appropriate shielding. Terminated per Electrical Systems Specification (431-SPEC-000008) ESS-127 ESR-13 The ES shall implement +28V discrete commands with appropriate shielding. Per Electrical Systems Specification (431-SPEC-000008) ESS-130 ESR-14 The ES shall implement 1 pulse-per-second to support C&DH, CRaTER, DLRE, LOLA and LEND RS-422 with termination per Electrical Systems Specification (431-SPEC-000008)

Lunar Reconnaissance Orbiter (LRO) Electrical System Level 2 Flow Down Key Thermal Requirements Level 2 Req. Level 3: Requirements Concept/Compliance Paragraph Requirement MRD-080 ESR-14 The ES shall size wire based on heaters for a minimum bus voltage of + 24 VDC Prevents over sizing of heaters at maximum bus voltage MRD-078 ESR-15 The ES shall support all heater circuits (instrument survival, instrument operational, spacecraft survival heaters (primary & redundant), spacecraft operational heaters, propulsion heaters (primary & redundant), gimbal heaters (primary & redundant), and deployable heaters. The ES shall support thermistors to verify temperatures. Maintain and monitor temperatures per Thermal System Specification (431-SPEC-000091)

Lunar Reconnaissance Orbiter (LRO) Electrical System Level 2 Flow Down Key Misc. Interface Requirements Level 2 Req. Level 3: Requirements Concept/Compliance Paragraph Requirement MRD-87, ESS-138 ESR-18 The ES shall provide multiple inhibits on all thrusters and isolation valves. Catastrophic hazard inhibits MRD-87, ESS-139 ESR-19 The ES shall provide harness to support all pyrotechnic requirements, isolating actuation devices from external energy sources by greater than 20 dB. The ES shall protect electroexplosive devices from electrostatic hazards. Protection against unintentional firing of pyrotechnics ESS-140-ESS-144, ESS-146-ESS-150 ESR-20 The ES shall provide harness and connectors to support component integration, anomaly investigation, environmental testing, and launch site operations. Spacecraft test panel ESR-145 ESR-21 The ES shall provide 3 independent launch vehicle separation switches. Sensing separation from launch vehicle, also used as a catastrophic hazard inhibit ESS-194 – ESS-234 ESR-22 The ES shall use qualified spaceflight connectors, materials, design and manufacturing processes. Best practices for materials, design and fabrication of spaceflight harnesses per Design and Development Guidelines for Spaceflight Electrical Harnesses (565-PG-8700.2.1)

Lunar Reconnaissance Orbiter (LRO) Electrical System Level 2 Flow Down Key Instrument Requirements Level 2 Req. Level 3: Requirements Concept/Compliance Paragraph Requirement TRA 4.3, MRD-35, MRD-115 ESR-23 The ES shall support 1 switched 1 A service, MIL-STD-1553 and 1 pulse-per-second (pps) for CRaTER Per CRaTER to Spacecraft Electrical Interface Control Document (EICD) (431-ICD-000094) ESR-24 The ES shall support 3 switched 2 A services (DLRE main, DLRE survival heaters, DLRE operational heaters), MIL-STD-1553 and 1pps for DLRE Per DLRE to Spacecraft EICD (431-ICD-000095) TRA 4.3, MRD-117 ESR-25 The ES shall support 2 switched 2 A service, support heritage LAMP telemetry and command interface for LAMP Per LAMP to Spacecraft EICD (431-ICD-000096) ESR-26 The ES shall support 1 switched 1 A service, MIL-STD-1553 and 1pps for LEND Per LEND to Spacecraft EICD (431-ICD-000097) ESR-27 The ES shall support 1 switched 2 A service, MIL-STD-1553, 20 MHz, and 1pps for LOLA Per LOLA to Spacecraft EICD (431-ICD-000098) TRA 4.3, MRD-36 ESR-28 The ES shall support 1 switched 2 A service, 1 switched 5 A service, and SpaceWire for LROC Per LROC to Spacecraft EICD (431-ICD-000099)

Lunar Reconnaissance Orbiter (LRO) Electrical System Level 2 Flow Down Key Spacecraft Requirements Level 2 Req. Level 3: Requirements Concept/Compliance Paragraph Requirement TRA 4.1, TRA 4.3, MRD-35, MRD-36, 115, 119, 120, 122-124, 078, 117 ESR-29 The ES shall support 2 unswitched 2 A services, 1 switched 2 A service. Provide MIL-STD-1553, SpaceWire, 1 pps, 20 MHz, RF, thermistors, and LAMP heritage interfaces for C&DH Per C&DH to Spacecraft EICD (431-ICD-000141) TRA 4.1, TRA 4.3, MRD-98, MRD-101- MRD-107 ESR-30 The ES shall support 9 unswitched services, 36 switched services, MIL-STD-1553, interface to battery and solar panels for Power System Electronics (PSE) Per PSE to Spacecraft EICD (431-ICD-000142) TRA 4.3, MRD-85, 87 ESR-31 The ES shall support 1 switched 15 A service, MIL-STD-1553, propulsion valve actuator, and deployment interfaces for Propulsion Deployment Electronics (PDE) Per PDE to Spacecraft EICD (431-ICD-000143) TRA 4.3, MRD-85 ESR-32 The ES shall support 2 switched 1 A services (2 Trackers), and MIL-STD-1553 for 2 Star Trackers Per Star Tracker to Spacecraft EICD (431-ICD-000144) ESR-33 The ES shall support 1 switched 2 A services, and MIL-STD-1553 for Intertial Measurement Unit (IMU) Per IMU to Spacecraft EICD (431-ICD-000145) TRA 4.1, TRA 4.3, MRD-119, 120, 122-124 ESR-34 The ES shall support 1 unswitched 2 A service (S-band RX), 1 switched 2 A service (S-band TX), 1 switched 10 A service (Ka-band TX), and RF interfaces (S-band RX, S-band TX, Ka-band TX) for Comm System Per Communications to Spacecraft EICD (431-ICD-000146)

Lunar Reconnaissance Orbiter (LRO) Electrical System Level 2 Flow Down Key Spacecraft Requirements Level 2 Req. Level 3: Requirements Concept/Compliance Paragraph Requirement TRA 4.3, MRD-85 ESR-35 The ES shall support propulsion catalyst bed heater, pyrotechnic valve, isolation valve, thrusters, pressure and pressure transducers interfaces for Propulsion System Per Propulsion to Spacecraft EICD (431-ICD-000147) TRA 4.1, MRD-85 ESR-36 The ES shall support 4 unswitched 2 A services (4 Integrated Reaction Wheels (IRWs)), MIL-STD-1553 for 4 Integrated Reaction Wheels Per IRW to Spacecraft EICD (431-ICD-000148) TRA 4.3, MRD-15, MRD-16 ESR-37 The ES shall support 1 switched 2 A service, MIL-STD-1553 for Gimbal Control Electronics Per Gimbal Controller Electronics to Spacecraft EICD (431-ICD-000149) MRD-98, MRD-101- MRD-107 ESR-38 The ES shall support solar array power and thermal sensors Per Solar Array to Spacecraft EICD (431-ICD-000150) MRD-102 ESR-39 The ES shall support battery power Per Battery to Spacecraft EICD (431-ICD-000151)

Lunar Reconnaissance Orbiter (LRO) Electrical System Level 2 Flow Down Key Technical Demonstration Requirements Level 2 Req. Level 3: Requirements Concept/Compliance Paragraph Requirement RLEP-LRO-P160, TRA 4.3, MRD-36 ESR-40 The ES shall support 1 switched 5 A service, 1 switched 2 A service, and SpaceWire for Mini-RF Per Mini-RF to Spacecraft EICD (431-ICD-000152)

Block Diagram (Data)

Block Diagram (Power) PSE OM-A USA1 (2 A) USA2 (5 A) USA3 (5 A) TT&C S-band RX IRW 1 IRW 2 NC Pyro Valves OPEN Prop Htrs Red Prop Valve Actuator SSR Unassigned LROC Optics Decon ST 2 TT&C S-band TX IMU Pressure Xducer NC Pyro Valves CLOSE A16 (2 A) PSE OM-B USB1 (2 A) USB2 (5 A) USB3 (5 A) B4 (5 A) B5 (10 A) B6 (15 A) B7 (2 A) B8 (1 A) B10 (5 A) B11 (1 A) B12 (2 A) B13 (2 A) B14 (2 A) B15 (2 A) C&DH Comm Card IRW 3 S/C Surv Htrs Prime Prop Catbed Htrs Prop Htrs Prime PDE Gimbal Control CRaTER Mini-RF ST 1 DLRE Surv Htr LAMP Red LOLA Gimbal Htrs Red Deploy Htrs B16 (2 A) PSE OM-C USC1 (2 A) USC2 (5 A) USC3 (5 A) C4 (5 A) C5 (10 A) C6 (15 A) C7 (2 A) C8 (1 A) C10 (5 A) C11 (1 A) C12 (2 A) C13 (2 A) C14 (2 A) C15 (2 A) C&DH IRW 4 S/C Surv Htrs Red Instr Surv Htrs Ka-band TX S/C Operational Htrs SA & HGA Release & Deploy LEND Instr Operational Htrs DLRE Main DLRE Operational Htrs LAMP Prime LROC Gimbal Htrs Prime C16 (2 A) PSE Monitor Card +28V Bus Backplane Battery Solar Array Module Solar Array

Verification By Analysis By Test Derating for current carrying capability Transmission line (RF) of high-speed signals (ex: SpaceWire) By Test Fit check on spacecraft mock-up Continuity and High Potential (Insulation/Resistance) for workmanship Network test (RF, SpaceWire, 1553) Bakeout S/C Level Integration Safe-to-mate - as part of subsystem integration Functional - as part of subsystem integration Orbiter Level EMI/EMC, Thermal Vacuum, Vibration

Summary Electrical Systems requirements are understood Electrical ICDs are in process some into CM, some in internal review Electrical Systems requirements are easily met Standard harness materials and processes We are ready to proceed with design