18c - 1NASA’s Goddard Space Flight Center
Electrical
Philip Luers
NASA/GSFC Code 561
August 16-17, 2005
18c - 2NASA’s Goddard Space Flight Center
Electrical Systems Document TreeMission
Requirements Document
(431-RQMT-000004)
Electrical SystemsSpecification(431-SPEC-
000008)
General ThermalSubsystem
Specification(431-SPEC-
0000091)
LRO SpaceWire Spec. (431-SPEC-000103)
CRaTER EICD (431-ICD-000094)
DLRE EICD (431-ICD-000095)
LAMP EICD (431-ICD-000096)
LEND EICD (431-ICD-000097)
LOLA EICD (431-ICD-000098)
LROC EICD (431-ICD-000099)
Electrical Systems Requirements
Document(431-RQMT-000140)
C&DH EICD (431-ICD-000141)
PSE EICD (431-ICD-000142)
Propulsion EICD (431-ICD-000147)
Reaction Wheels EICD (431-ICD-000148)
Star Tracker EICD (431-ICD-000144)
Inertial Meas. Unit EICD (431-ICD-000145)
Communications EICD (431-ICD-000146)
Specific InterfacesConnectors, pinouts
Specific InterfacesConnectors, pinouts
PDE EICD (431-ICD-000143)
Gimbal Controller EICD (431-ICD-000149)
Solar Array EICD (431-ICD-000150)
Battery EICD (431-ICD-000151)
Delta II PPG(MDC 00H0016)
Heaters, Thermistors
Power, 1553, SpaceWire, 1 pps,
RS-422, Grounding, Isolation, Shielding,
Charging
Mini-RF EICD (431-ICD-000152)
18c - 3NASA’s Goddard Space Flight Center
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 KeyPower Requirements
18c - 4NASA’s Goddard Space Flight Center
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. Best practice for charging avoidance per NASA-HDBK-4001
ESS-188 – ESS-193
ESR-8 The ES shall be designed to minimize internal charging. Best practice for charging avoidance per NASA-HDBK-4001
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 KeyGrounding Requirements
18c - 5NASA’s Goddard Space Flight Center
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 KeyData Requirements
18c - 6NASA’s Goddard Space Flight Center
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 KeyThermal Requirements
18c - 7NASA’s Goddard Space Flight Center
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 KeyMisc. Interface Requirements
18c - 8NASA’s Goddard Space Flight Center
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)
TRA 4.3, MRD-35, MRD-115
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)
TRA 4.3, MRD-35, MRD-115
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)
TRA 4.3, MRD-35, MRD-115
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 KeyInstrument Requirements
18c - 9NASA’s Goddard Space Flight Center
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)
TRA 4.3, MRD-85
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 KeySpacecraft Requirements
18c - 10NASA’s Goddard Space Flight Center
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 KeySpacecraft Requirements
18c - 11NASA’s Goddard Space Flight Center
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)
Lunar Reconnaissance Orbiter (LRO)
Electrical System Level 2 Flow Down KeyTechnical Demonstration Requirements
18c - 12NASA’s Goddard Space Flight Center
Block Diagram (Data)
18c - 13NASA’s Goddard Space Flight Center
Block Diagram (Power)PSE OM-A
USA1 (2 A)
USA2 (5 A)
USA3 (5 A)
A4 (5 A)
A5 (10 A)
A6 (15 A)
A7 (2 A)
A8 (1 A)
A10 (5 A)
A11 (1 A)
A12 (2 A)
A13 (2 A)
A14 (2 A)
A15 (2 A)
TT&C S-band RXIRW 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
Unassigned
Pressure Xducer
NC Pyro Valves CLOSEA16 (2 A)
PSE OM-BUSB1 (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 CardIRW 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 HtrsB16 (2 A)
PSE OM-CUSC1 (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&DHIRW 4
S/C Surv Htrs Red
Instr Surv Htrs
Ka-band TX
S/C Operational Htrs
SA & HGA Release & Deploy
LEND
Instr Operational Htrs
Unassigned
DLRE Main
DLRE Operational Htrs
LAMP Prime
LROC
Gimbal Htrs PrimeC16 (2 A)
PSE Monitor Card
+28V Bus Backplane
BatterySolar Array ModuleSolar Array
18c - 14NASA’s Goddard Space Flight Center
Verification
• By Analysis– 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
18c - 15NASA’s Goddard Space Flight Center
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