18c - 1 nasa’s goddard space flight center electrical philip luers nasa/gsfc code 561 august...

18c - 1NASA’s Goddard Space Flight Center

Electrical

Philip Luers

NASA/GSFC Code 561

August 16-17, 2005


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)


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




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


Electrical System Level 2 Flow Down KeyGrounding Requirements




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)


Electrical System Level 2 Flow Down KeyData Requirements




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)


Electrical System Level 2 Flow Down KeyThermal Requirements




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)


Electrical System Level 2 Flow Down KeyMisc. Interface Requirements




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)


Electrical System Level 2 Flow Down KeyInstrument Requirements




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)


Electrical System Level 2 Flow Down KeySpacecraft Requirements




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)


Electrical System Level 2 Flow Down KeySpacecraft Requirements




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)


Electrical System Level 2 Flow Down KeyTechnical Demonstration Requirements


Block Diagram (Data)


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


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


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

18c - 1 nasa’s goddard space flight center electrical philip luers nasa/gsfc code 561 august...

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