Taller de Diseño de Picosatélites (CUBESATS) Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierray Estaciones de Tierray Estaciones de Tierray Estaciones de Tierra
Session Session 44SubsystemsSubsystemsyy
J M l d l CJ M l d l C M d R iM d R iJuan Manuel del CuraJuan Manuel del CuraDirector de Director de ProyectoProyecto, SENER, SENER
DptoDpto. . VehículosVehículos AerospacialesAerospaciales, ,
Mercedes RuizMercedes RuizIngenieraIngeniera de de SistemasSistemas, SENER, SENER
[email protected]@sener.es
ETSIA. UPMETSIA. [email protected]@sener.es
1Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
ContentContent
• Picosat=Picodesign?• Picosat subsystems
D t H dli g• System Engineering process• Main elements of a mission/spacecraft
– Data Handling – Communications– Power p
• System drivers • Picosat payloads
– Thermal– Structure
P l ip y
• Picosat subsystems– Attitude and Orbit Control
– Propulsion
– Data Handling – Communications– PowerPower– Thermal– Structure
2Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
– Propulsion
D t H dliD t H dliData HandlingData HandlingSubsystemSubsystemSubsystemSubsystem
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Data Handling SubsystemData Handling Subsystem
Objectives:Objectives:Objectives:Objectives:• Two main functions of the Data Handling subsystem:
– Distribution of all commands to all S/C elements– Preparation of the information transferred to ground:
• Housekeeping• Mission dataMission data
• Additional functions:– S/C timekeeping– Computer health monitoring– Security interfacesSecurity interfaces
• All these functions can be implemented in a (set of) t ( )
4Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
computer(s)
Data Handling SubsystemData Handling Subsystem
Data Handling Design ProcessData Handling Design ProcessReliability
Command Rate
Number of
channelsOn board
Computer?Bus
constraints
Command Storage?
Mission Time
clock?Satellite Lifetime
Identification of functionsIdentification of
requirements and
gComputer Watchdog
?
ACSconstraintsH/K
RateNumber
of channels
P/L DataRate
Computer I/F
ACS functions
?
Schedule
Determination of the complexity of CDH
functions
Radiation Environmen
t Budget
functions
Determination ofEstimation of size,
mass and power for
5Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Determination of overall CDH level of
complexity
mass and power for each component
Data Handling SubsystemData Handling Subsystem
System Complexity DefinitionSystem Complexity DefinitionSimple Typical Complex
System ComplexityRequirement or Constraint Simple Typical Complex
Processing CommandsCMD rates 50 cmds/s 50 cmds/s ≥50 cmds/sComputer interface none Computer or stored (not both) yesStored commannds none Computer or stored (not both) not needed
Requirement or Constraint
( )Number of channels <200 channels 300-500 channels > 500 channels
Processing of Telemetry DataTLM rates
H/K data 500-4kbps 4-64kbps 64-256kbpsPayload data none 1-200kbps 10kbps-10MbpsPayload data none 1 200kbps 10kbps 10Mbps
Computer interface none none yesNumber of channels <200 channels 400-700 channels > 500 channels
OtherMission time clock none included includedComputer watchdog none included if OBC includedComputer watchdog none included if OBC includedAOCS functions none none included
Bus Constraints Single Unit Single Unit or Multiple Units Integrated or DistributedReliability-Class B parts
Single String 0,8233 0,761 0,6983Redundant 0 9875 0 9736 0 9496Redundant 0,9875 0,9736 0,9496
Reliability-Class S partsSingle String 0,9394 0,9083 0,8285Redundant 0,9987 0,9964 0,9829
Radiation Environment /total dose) <2krads 2-50krads 50krads-1Mrads
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Schedule (in months, after order)Class B parts 6-12 6-12 9-18Class S parts 9-18 9-18 9-24
Data Handling SubsystemData Handling Subsystem
Parametric Estimation of CDH Size, Mass and PowerParametric Estimation of CDH Size, Mass and PowerSimple Typical Complexp yp p
Command only 1500-3000 2000-4000 5000-6000Telemetry only 1500-3000 4000-6000 9000-10000Combined Systems 2500-6000 6000-9000 13000-15000
Size (cm3)
yCommand only 1,5-2,5 1,5-3,0 4,0-5,0Telemetry only 1,5-2,5 2,5-4,0 6,5-7,5Combined Systems 2 75-5 5 4 5-6 5 9 5-10 5
Mass (kg)
Combined Systems 2,75 5,5 4,5 6,5 9,5 10,5Command only 2 2 2Telemetry only 5-10 10-16 13-20Combined Systems 7 12 13 18 15 25
Power (nominal) (W) Combined Systems 7-12 13-18 15-25(W)
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Data Handling SubsystemData Handling Subsystem
Computer architecture at system levelComputer architecture at system level
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Data Handling SubsystemData Handling Subsystem
Elements of an onboard computerElements of an onboard computer
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Data Handling SubsystemData Handling Subsystem
Definition of the onboard computer:• Identify the spacecraft bus and payload operational modes• Allocate top‐level requirements for the computer system• Define sub system interfaces• Define sub‐system interfaces• Specify baseline computer system
– Define computer systems operational modes and states– Functionally partition and allocate computational
requirements to • spacecraft sub‐systems, hardware, or software
d t ti• ground station– Analyze data flow– Evaluate candidate architectures
S l b i hi– Select basic architecture– Develop baseline system configuration
• Do we need a new computing system, or can we use an old h i l d ifi d
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system that is already certified?
Data Handling SubsystemData Handling Subsystem
Computer functional partitioningComputer functional partitioning
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Data Handling SubsystemData Handling Subsystem
Onboard computer architectureOnboard computer architecture
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Data Handling SubsystemData Handling Subsystem
Computer Resources EstimationComputer Resources Estimation
B h kB h kBenchmark Benchmark ProgrammesProgrammes
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Data Handling SubsystemData Handling Subsystem
Software Estimation ProcessSoftware Estimation Process
Identification of application functions
allocated to the
Breakdown of the function into basic
elementscomputer
elements
Definition of the real-time execution
frequency for each ofBottom
s-upSimilarit
y frequency for each of the basic elementsEstimation of the
SLOC and memory need for each
Bottoms-up
Similarity
function
Estimate throughput requirements
Similarity
Estimate the operating system and
overhead requirementsDetermination of the
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requirementsDetermination of the margins for growth and on-orbit spare
Data Handling SubsystemData Handling Subsystem
Development Phase IssuesDevelopment Phase Issues
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Data Handling SubsystemData Handling Subsystem
Computer system integration and testingComputer system integration and testing
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Data Handling SubsystemData Handling Subsystem
Software EstimationsSoftware EstimationsSize (Kwords)Function Typical Typical
Code Data
CommunicationsCommand Processing 1,0 4,0 7,0 10,0Telemetry Processing 1,0 2,5 3,0 10,0
Attitude Sensor Processing
throughput (KIPS)
Execution Frequency
Attitude Sensor ProcessingRate Gyro 0,8 0,5 9,0 10,0Sun Sensor 0,5 0,1 1,0 1,0Earth Sensor 1,5 0,8 12,0 10,0Magnetometer 0,2 0,1 1,0 2,0Star Tracker 2,0 15,0 2,0 0,01
Attit d D t i ti & C t lAttitude Determination & ControlKinematic Integration 2,0 0,2 15,0 10,0Error Determination 1,0 0,1 12,0 10,0Precession Control 3,3 1,5 30,0 10,0Magnetic Control 1,0 0,2 1,0 2,0Thruster Control 0,6 0,4 1,2 2,0Reaction Wheel Control 1,0 0,3 5,0 2,0CMG Control 1,5 0,3 15,0 10,0Ephemerids Propagation 2,0 0,3 2,0 1,0Complex Ephemerids 3,5 2,5 4,0 0,5Orbit Propagation 13,0 4,0 20,0 1,0
AutonomyAutonomySimple Autonomy 2,0 1,0 1,0 1,0Complex Autonomy 15,0 10,0 20,0 10,0
Fault DetectionMonitors 4,0 1,0 15,0 5,0Fault Coreection 2,0 10,0 5,0 5,0
Other Functions
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Other FunctionsPower Management 1,2 0,5 5,0 1,0Thermal Control 0,8 1,5 3,0 0,1Kalman Filter 8,0 1,0 80,0 0,01
Data Handling SubsystemData Handling Subsystem
Conversion of SLOC to Words of MemoryConversion of SLOC to Words of Memory
Language Assembly I t ti
Bytes per SLOC f 32 bitInstructions per
SLOCSLOC for 32-bit
ProcessorFORTRAN 6 36C 7 42PASCAL 6 36JOVIAL 4 24JOVIAL 4 24ADA 5 30
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Data Handling SubsystemData Handling Subsystem
Operating SystemsOperating Systems
Function Size (Kwords) Typical Comments
Code Data
Executive 3,5 2 0,3n n is the number of tasks scheduled per secondT i l 200
throughput (KIPS)
Typical: n=200Run-Time Kernel 8 4 see
commentsThroughput is included in functions which use the features
I/O Device Handlers
2 0,7 0,05m m is the number of data words handled per secondHandlersBuilt-In Test and Diagnostics
0,7 0,4 0,5 Throughput estimated assuming 0,1Hz
Math Utilities 1,2 0,2 see comments
Throughput is included in estimate of application throughput
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Data Handling SubsystemData Handling Subsystem
Flight ComputersFlight ComputersNo se puede mostrar la imagen. Puede que su equipo no tenga suficiente memoria para abrir la imagen o que ésta esté dañada. Reinicie el equipo y, a continuación, abra el archivo de nuevo. Si sigue apareciendo la x roja, puede que tenga que borrar la imagen e insertarla de nuevo.
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DHS Examples DHS Examples –– Generic CubesatGeneric Cubesat
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DHS Examples DHS Examples –– Generic CubesatGeneric Cubesat
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DHS Examples DHS Examples –– Generic CubesatGeneric Cubesat
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DHS Examples DHS Examples –– Generic CubesatGeneric Cubesat
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DHS Examples DHS Examples –– Generic CubesatGeneric Cubesat
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DHS Examples DHS Examples -- AAUAAU
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DHS Examples DHS Examples –– XIXI--IVIV
CW-CtoERx-EtoC
Rx-TNCThermometer0 to 7
MPX
CW-TNCCW-EtoC
Rx-CtoERx-TNC
OBC MPX_SEL0 ~2
Reset Signal (Power Sub Sys.)
Tx-TNCTx-CtoE
Tx-EtoC
OBC Program&
(Power Sub Sys.)
SEL Detect
C-DCDC 5VTo Comm
E-DCDC 5V
ROM Read/WritePins
SCL LineROM0ROM0ROM0ROM0
Battery VoltageCharge Current
Battery Charger IC Reset Signal
Sub Sys.
SDA Line
O 0ROM0ROM0ROM0ROM0ROM0ROM0
y g g
(Structure Mother Board)
Solar Cell Current1 t 6MPX
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1 to 6MPX
DHS Examples DHS Examples –– XIXI--IVIV
OBCCRNT /ROND /SOLATEMP /VOLT
Uplink CommandFixed length = 17 bytes
Tx-TNC CW-TNC
ANTD /CRNT /DCDCMTQC /POWR/ROMDSOLA /TEMP /VOLTTx TNC CW TNC
Ground Station in UT
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DHS Examples DHS Examples –– XIXI--IVIV
Components of ElectronicsComponents of ElectronicsFor Thermometer
ROM READ/WRITE Pin
For ThermometerJumperPin For ROM
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ROM ModuleFor CameraXI-II model
DHS Examples DHS Examples –– XIXI--IVIV
Components of ElectronicsComponents of Electronics--(2)(2)OPA M d lOPAmp Module Program Pin
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Thermometer Module XI-II model
DHS Examples DHS Examples –– XIXI--IVIV
Components of ElectronicsComponents of Electronics--(3)(3)
PIC 16F877• Clock :4MHz• Memory :8kword• RAM :368bytes• EEPROM :256bytes
ROM (24LC256)
EEPROM :256bytes• Operative Voltage:2.0~5.5V
ROM (24LC256)• I2C serial EEPROM• Memory :256Kbit(32Kbyte)• Memory :256Kbit(32Kbyte)• Max erase/write cycles:100,000• Max write-cycle time :5ms
M l k f 400kH
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• Max clock frequency :400kHz
DHS Examples DHS Examples –– QuakesatQuakesat
• Pros Linux– Drivers (baypac & ax25) built‐in– <10k loc+linux = flight software
• 3k loc for low level A/D timers– Utilities already written
• Md5sums ( errror checking)• Bzip2 ( file compression )• Shell utilities• Shell utilities
• Pros Prometheus– 16 channel/16bit A/D built‐in
H d ti /i t t– Hardware timers/interrupts– Multitasking 66 MHz– 32 Meg RAM/128 Meg Flash
• Cons• Cons– Power hog 2.5 W– Flexibility require more testing!!
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C i tiC i tiCommunicationsCommunicationsSubsystemSubsystemSubsystemSubsystem
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Communications SubsystemCommunications Subsystem
ObjectivesObjectives
• Main functions of the Communication subsystem:– Interface between the spacecraft and the ground system
• Transfer of P/L data• Transfer of H/K dataT f f t d• Transfer of operator commands
– Carrier tracking– Command reception and detectionCommand reception and detection– Telemetry modulation and transmission– Rangingg g– Subsystem operations
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Communications SubsystemCommunications Subsystem
Definition of the communications architectureDefinition of the communications architectureUse of relay satellites and
Mission data flow diagram
Data sources,
end users and
locationsQuantity of
data per unit time
Identification of links and ground station locations
relay ground stations? Data processing
location
Identification of Communicationrequirements
diagram unit timeSelection of alternative
communications architectures
q
Transmission delay
Access time
Availability,
reliabilityEvaluate
Design & Size Each
Sampling rates
alternatives and compare
Determination of Data Rates for Each
Link
Design & Size Each Link
Quantization levels
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Documentation reasons for selection
Bits per sample
Communications SubsystemCommunications Subsystem
Definition of the communications architectureDefinition of the communications architecture
f l k• Types of links:– Ground station‐to‐satellite uplink
Satellite to ground station do nlink– Satellite‐to‐ground station downlink– Satellite‐to‐satellite crosslink– Intersatellite linkIntersatellite link
• Constraints:– Direct viewDirect view– Frequencies high enough– Satellite‐Ground station geometry
36Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Communications SubsystemCommunications SubsystemArchitectureArchitecture AdvantagesAdvantages DisadvantagesDisadvantagesStore and forward •Low‐cost launch
•Low‐cost satellite•Long message access time and transmission delay (up to several hours)
•Polar coverage with inclined orbit
GEO •No switching between satellites•Ground station antenna tracking often not required
•High‐cost launch•High‐cost satellite•Need for stationkeepingp g•Propagation delay•No coverage of polar regions
Molniya •Provides coverage of polar regions•Low‐cost launch per satellite
•Requires several satellites for continuous coverage of one hemisphere•Need for ground station antenna pointing and satellite handover•Network control more complex•Need for stationkeeping
GEO with crosslink •Communication over greater distance without •Higher satellite complexity and costGEO with crosslink •Communication over greater distance without intermediate ground‐station relay•Reduced propagation delay•No ground stations in foreign territory:
–Increased securityR d d t
•Higher satellite complexity and cost•Need for stationkeeping•Relay satellite and launch costs•No coverage of polar regions
–Reduced cost
Low‐Altitude Multiple satellites with crosslink
•Highly survivable‐multiple paths•Reduced jamming susceptibility due to limited Earth view area•Reduced transmitter power due to low altitude
•Complex link acquisition ground station (antenna pointing, frequency, time)•Complex dynamic network control•Many satellites required for high link availability
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p•Low‐cost launch per satellite•Polar coverage with inclined orbit
y q g y
Communications SubsystemCommunications Subsystem
Communications architecture functionsCommunications architecture functions
• TTC:– TrackingTracking– TelemetryC di
••Point to pointPoint to point– Commanding
• Data collection••BroadcastBroadcast
• Data relay
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Communications SubsystemCommunications Subsystem
Criteria for selecting the communications architectureCriteria for selecting the communications architecture•Earth coverage
OrbitOrbit
RF S tRF S t
•Range•View times
•Carrier frequencyRF SpectrumRF Spectrum
Data rateData rate
•Legal assignment
•Direct impact on sizeO b d i
CriteriaCriteriaDuty factorDuty factor
•On board processing
•Mission and orbit
E i li bili
LinkLinkAvailabilityAvailability
•Equipment reliability•Redundancies•Time required for reparation•Outgage•Use of alternative links
Link Access TimeLink Access Time •Mission dependant
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ThreatThreat •Mission dependant
Communications SubsystemCommunications Subsystem
Main Elements of the on board Communication S/SMain Elements of the on board Communication S/S
Power
Data
OBDHCmds Tlm
TransmitterTransponder A
Receiver
Storage Tlm
OBDH Tlm
OBDH Cmds
LowPassFilter
BandRejectFilter
Transmit
Diplexer
GNC
Antenna A
Gimbal/AntennaControlReceiver
Transmitter
DataStorage Tlm
OBDH Tlm
LowPass
BandReject
RF Switch2P2T
Di l
Electronics
Antenna B
Transponder BReceiver
OBDH Tlm
OBDH CmdsFilter Filter Diplexer
GNC
Gimbal/AntennaControl
ElectronicsTransmitRF Switch
LowPass
Power 2P2T
Cmds Tlm
Filter
LowPass
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Cmds TlmOBDH
Filter
Communications SubsystemCommunications Subsystem
TTC Design ProcessTTC Design ProcessData rate
Existing, assigned
Range, orbit and S/C
geometry
and volume
Minimum
elevation angle
Select frequency
Data rate
Definition of requirements
Determination of the required bandwidth
Data rate
W t q
Subsystem trades based on link budget
Worst case rain
conditionsBit error
rate
Receiver
Calculation of performance
Receiver noise temperature
gainpparameters
Estimation of
EIRP
System trades between the different
subsystems
Transmitter
gain
Transmitter
Estimation of subsystem weight
and powerG/T
M i
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power MarginDocumentation and
iteration
Communications SubsystemCommunications Subsystem
Main RequirementsMain RequirementsRequirementRequirement Alternative/considerationsAlternative/considerationsqq
Data rates:Command
Health & status TM4000bps typical, 8‐64 bps deep space8000bps is common
Mission/Science Low <32bps; Medium: 32bps‐1Mbps; High>1Mbps‐1Gbps
Data volume Record data, compress data and transmit during longer windows
Data storage Solid‐state recorders 128x106 bitsg
Frequency Using existing assigned frequencies and channels
Bandwidths Use Shannon’s theorem to calculate channel capacity
Po er Use larger antennas higher efficienc amplifiersPower Use larger antennas, higher efficiency amplifiers
Mass Use TWTAs for higher RF power output to reduce antenna size
Beamwidth Different antenna types, beam shapes and beamwidths
EIRP (Eff ti I t i A t i ( i ) i th t itt i t EIRP (Effective Isotropic Radiated Power)
As antenna size (gain) increases, the transmitter power requirement decreases
G/T (Antenna gain to system noise
)
Various communication system temperatures and G/Ts
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temperature)
Communications SubsystemCommunications Subsystem
TTC Requirements on other subsystemsTTC Requirements on other subsystemsAOCSAOCS:: PayloadPayload::AOCSAOCS::•• Antenna Pointing (Gimballed)Antenna Pointing (Gimballed)••Pointing reqs of the lesser of 1/10 Pointing reqs of the lesser of 1/10 of antenna beamwidth or 0.3degof antenna beamwidth or 0.3deg
PayloadPayload::••Storing mission dataStoring mission data••RF and EMC interface reqsRF and EMC interface reqs••Special reqs for modulation, coding and decodingSpecial reqs for modulation, coding and decodinggg
•• ClosedClosed--loop pointing reqsloop pointing reqsSpecial reqs for modulation, coding and decodingSpecial reqs for modulation, coding and decoding
OBDHOBDH::••Command and telemetry data ratesCommand and telemetry data rates
TTCTTC ••Clock, bit sync and timing reqsClock, bit sync and timing reqs••22--way comm reqsway comm reqs••Autonomous fault detection and Autonomous fault detection and recovery reqsrecovery reqsSt t /Th lSt t /Th l recovery reqsrecovery reqs••Command and telemetry electrical Command and telemetry electrical I/FI/F
Structure/Thermal:Structure/Thermal:••Heat sinks for travelling wave tube Heat sinks for travelling wave tube amplifiersamplifiers••Heat dissipation of all active boxesHeat dissipation of all active boxes
Propulsion:Propulsion:••NoneNone
Power:Power:••Distribution reqsDistribution reqs
Heat dissipation of all active boxesHeat dissipation of all active boxes••Location of TTC electronics and Location of TTC electronics and antennasantennas•• A clear FoV and movement for all A clear FoV and movement for all
i b ll d ti b ll d t
43Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
gimballed antennasgimballed antennas
Communications SubsystemCommunications Subsystem
TTC Constraints on other subsystemsTTC Constraints on other subsystems
AOCSAOCS::PayloadPayload::••Maximum data ratesMaximum data rates
•• Pointing for fixed antennasPointing for fixed antennas•• Pointing lossPointing loss
•• Maximum data volumeMaximum data volume
TTCTTC
OBDHOBDH::••On board storage and On board storage and processingprocessing
Propulsion:Propulsion:Structure/Thermal:Structure/Thermal: Propulsion:Propulsion:••NoneNone
Power:Power:A t d litA t d lit
••Temperature uncertainty Temperature uncertainty leading to frequency leading to frequency uncertaintyuncertainty
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••Amount and quality Amount and quality of powerof power
Communications SubsystemCommunications Subsystem
Design ParametersDesign Parameters Antenna sidelobeLevels
Design to minimise. Sidelobes degrade the antenna’s directionalityLevels
Polarization
directionality.
Circular or linear. For reducing losses, compatibility is needed.
FrequencySt bilit
, p y
For quick acquisition: known and stable. Short-term, temperature
DesignDesignParametersParameters
Stability
Capture&
, pand ageing.
Capture: range of frequencies for locking the signal. Tracking:
Tracking Rangelocking the signal. Tracking: range with the signal locked
Diplexer Same antenna for Rx and Tx. Low isolation requires a band rejectIsolation
Coupling between
isolation requires a band-reject filter.
T b d d i b th h l
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p gAntennas
To be reduced in both channels
Communications SubsystemCommunications Subsystem
Antenna typesAntenna types
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Communications SubsystemCommunications Subsystem
Selection criteriaSelection criteria •Mass•Volume
P f
Volume•Power•Bit error rateN i fiPerformance •Noise figure
•Frequency stability•Insertion loss
SelectionSelectionCriteriaCriteria
•Reliability•Efficiency
Compatibility•With existing systems•SGLS
Oth
•TDRSS
•Technology risk
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Other Technology risk•Heritage
Communications SubsystemCommunications Subsystem
Carrier frequenciesCarrier frequencies
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Communications SubsystemCommunications Subsystem
Detected powerDetected power
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Communications SubsystemCommunications Subsystem
Receiver noiseReceiver noise
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Communications SubsystemCommunications Subsystem
Other noise sourcesOther noise sources
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Communications SubsystemCommunications Subsystem
Signal to noise and information contentSignal to noise and information content
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Communications SubsystemCommunications Subsystem
Signal to noise ratio per bitSignal to noise ratio per bit
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Communications SubsystemCommunications Subsystem
Typical command and telemetry characteristicsTypical command and telemetry characteristics
54Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Communications SubsystemCommunications SubsystemTypical Communication Satellite Transponder CharacteristicsTypical Communication Satellite Transponder Characteristics
55Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Communications Examples Communications Examples -- AAUAAU
56Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Communications Examples Communications Examples –– XIXI--IVIV
OBCOBCS
Tx TNCC16C622
Rx TNCC16C 11
Telemetry data Beacon data Up-link command
AD Convert
SensorsSensors
NegotiationMorse encoderPIC16C622 PIC16C711
AX25 Coded datawith Parity
AX25 Coded command
M C d d d
Morse encoderPIC16C716
PLL PLLModulator
MX614Demodulator
MX614
FSK modulated command
Morse Coded dataPTT Control
FSK modulated data
PLLControl
PLLControl
Control
Nishi RF Lab.Custom made
FM transmitter
Nishi RF Lab.Custom made
CW transmitter
Nishi RF Lab.Custom madeFM receiver
FSK modulated data Control
Half wave lengthdipole antenna
Half wave lengthmonopole antenna
FM transmitter CW transmitter FM receiver
Antenna SW
switching
57Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
dipole antenna monopole antennaAntenna SW
Communications Examples Communications Examples –– XIXI--IVIV
Tx TNC (AX.25 encoder)Tx TNC (AX.25 encoder)
■Tx TNC:Micro controller PIC16C622-program memory(EPROM) : 2 kbyte-data memory(RAM) : 128 bytedata memory(RAM) : 128 byte-clock : 4 MHz-I/O port : 13 (4 AD Converters)-power consumption : 2 0 mA @ 5V-power consumption : 2.0 mA @ 5V
■Tx TNC receives telemetry data from OBC ■Puts Parity byte for error detection■E d th t l t d t ith AX 25 t l PIC16C622■Encodes the telemetry data with AX.25 protocol■Sends encoded data to FSK modulator
PIC16C622
AX.25 Protocol■This protocol is mainly used for data transmission by HAM■Every Amateur Radio Station all around the world can decode our telemetry data!!!
58Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
our telemetry data!!! Flag Destination Source Control PID parity data parity data FCS Flag
AX.25 frame structure(with Parity)
Communications Examples Communications Examples –– XIXI--IVIVTx TNC ProgramTx TNC Program
Start & InitializationStart & Initialization
data from OBC ?No
Receive data from OBCYes
Packetize into AX25 format
Send packet to FSK modulator
59Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
p
Communications Examples Communications Examples –– XIXI--IVIV
FM TransmitterFM Transmitter
■FM Transmitter is used to transmit telemetry data■Nishi RF Laboratory custom made transmitter
f 437 490MH-frequency:-band width:-RF output power:
437.490MHz20kHz1W
-input power:-operative temp.:-volume:
under 6W-30 ~+6090×60×10cm FM transmitter
(including CW transmitter)
60Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
FM transmitter System Diagram
Communications Examples Communications Examples –– XIXI--IVIV
CW Generator ProgramCW Generator ProgramStart & InitializationStart & Initialization
No
YOBC ready OBC ready
to send data?Data Sampling
Receive data from OBCYes
N
Yesto send data?to send data?
Counter < 10secCounter < 10sec
Data sensing (AD Convert)
UT1 www space t u tokyo ac jp
No
UT1 www.space.t.u-tokyo.ac.jpUT2 AA BB CC UT3 DD EE FF Data SendingUT4 GG HH II
UT5 JK LM NO
Data Sending
61Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
UT6 PQ RS TU
Communications Examples Communications Examples –– XIXI--IVIV
Rx TNC (AX.25 decoder)Rx TNC (AX.25 decoder)
■Rx TNC:Micro controller PIC16C711program memory(EPROM) : 1 kbyte-program memory(EPROM) : 1 kbyte
-data memory(RAM) : 64 byte-clock : 4 MHz
4 AD C t (8bit)-4 AD Converters (8bit)-power consumption : 2.0 mA @ 5V
■Rx TNC receives AX.25 encoded command from FSK demodulator
■Decodes it and sends command to OBC PIC16C711
OBC Reset System■If the command is “Reset Command”, resets OBC■Monitors OBC’s current and resets OBC in case of SEL
62Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
■Monitors OBC s current and resets OBC in case of SEL(Countermeasure of OBC’s SEL)
Communications Examples Communications Examples –– XIXI--IVIV
Rx TNC ProgramRx TNC Program
Interruption Routine
Start & InitializationMain Routine
Interruption Routine
set ‘Receiving’ flag
Receive Uplink command A/D convert ‘Total I’A/D convert ‘Total I’
g gset Receiving flag
Command = “rset”Command = “rset”or flag rst 1 ?
Yes No
‘Total I’ > Threshold ?‘Total I’ > Threshold ?
Yes
Reset OBCReset OBC
or flag_rst = 1 ?or flag_rst = 1 ?
Wait 10 [ms]
OBC ready to receive?OBC ready to receive?No
Yes
g_flag_rst = 1
[ ][ ]Send serial data to OBCSend serial data to OBCflag_rst = 0flag_rst = 0
63Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
clear ‘Receiving’ flag
Communications Examples Communications Examples –– XIXI--IVIV
FM ReceiverFM Receiver
■FM Receiver is used to receive up-link command■FM Receiver is used to receive up link command■Nishi RF Laboratory custom made receiver
-frequency:-input power:
145.835MHzunder 100mW
-receive sensitivity:-receive output:
ti t
under -16dBμ16dBV typ.30 +60-operative temp.:
-volume:-30 ~+6050×60×10cm FM receiver
64Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Communications Examples Communications Examples –– XIXI--IVIV
Antenna ConfigurationAntenna Configuration
Antenna for Transmitters430MHz band Half wavelength dipole antenna
Antenna for Receiver144MHz Half wavelength monopole antenna144MHz Half wavelength monopole antenna
65Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Communications Examples Communications Examples –– XIXI--IVIV
Antenna Pattern (Transmitter)Antenna Pattern (Transmitter)
Antenna Absolute GainTransmitters' Half wavelength dipole Antenna
(dBm)(dBm)
-5 00
0.00
5.00 The gain which we can decode th d t i
-20.00
-15.00
-10.00
5.00 the data in our ground station
-25.00
Gt
66Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Gt,req
Communications Examples Communications Examples –– XIXI--IVIV
Antenna Pattern (Receiver)Antenna Pattern (Receiver)
Antenna GainReceiver's Half wavelength monopole antenna
(dBm)
-30.00
-25.00
-20.00
-45.00
-40.00
-35.00
30.00
-55.00
-50.00
67Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Communications Examples Communications Examples –– XIXI--IVIV
Link Budget (Telemetry Tx)Link Budget (Telemetry Tx)Link B udgetT l t (TD M A )
Sym bol U nit Telem etry R em ark
Frequency f M H z 437.400Transm it P W 0.600 Param eterTransm it P dB W -2.218
Telem etry (TD M A )
Transm itter Line Loss Ll dB -3.000 U sually -1dB~-3dBTransm it A ntenna H alf-Pow er B eam w id θt deg 110.000 Ideal dipl ePeak Transm it A ntenna G ain G pt dB 2.148 Ideal dipl eTransm it A ntenna Pointing O ffset et deg 90.000 U ncontrolledTransm it A ntenna Pointing Loss Lpt dB -8.033
CUBESATComm. System
Transm it A ntenna G ain G t dB -5.885Equiv. Isotropic R adiated Pow er EIR P dB W -11.103Propagation Path Length S km 1439.940 50kbyte/1passSpace Loss Ls dB -148.434Propagation & Polarization Loss La dB -0.470 Polarization (-0.3dB )
Comm. System
Peak R eceive A ntenna G ain G rp dB 12.500 G S 435H S20R eceive A ntenna H alf-Pow er B eam w idtθr deg 29.000 G S 435H S20R eceive A ntenna Pointing Error er deg 15.000 A ssum ptionR eceive A ntenna Pointing Loss Lpr dB -3.210R eceive A ntenna G ain G r dB 9.290
UT’sGround Station
System N oise Tem perature Ts dB K 25.700D ata R ate R bps 1200.000 M X614Eb Eb0 dB 21.390B it Er B ER 0.000
R equired Eb/N 0 R eq Eb/N 0dB -H z 13.000 FSK, B ER =10-5
68Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Im plem entation Loss dB -5.000M argine dB 3.390
Communications Examples Communications Examples –– XIXI--IVIV
Link Budget (Command Rx)Link Budget (Command Rx)Link B udgetU li k C d
Sym bol U nit U plink R em ark
Frequency f M H z 145.835Transm it P W 20.000 Param eterTransm it P dB W 13.010
U plink C om m and
Transm itter Line Loss Ll dB -3.000 U sually -1dB~-3BTransm it A ntenna H alf-Pow er B eam w id θt deg 33.000 G S 144H S12Peak Transm it A ntenna G ain G pt dB 10.000 G S 144H S12Transm it A ntenna Pointing O f fe tet deg 15.000 A ssum ptionTransm it A ntenna Pointing Loss Lpt dB -2.479
UT’sGround Stationg p
Transm it A ntenna G ain G t dB 7.521Equiv. Isotropic R adiated Pow er EIR P dB W 17.531Propagation Path Length S km 1439.940Space Loss Ls dB -138.894Propagation & Polarization Loss La dB -0.470 Polarization (-0.3dB )p gPeak R eceive A nteG rp dB -2.521 M onopoleR eceive Antenna H alf-Pow er B eam w idtθr deg 100.000 M onopoleR eceive Antenna Pointing Error er deg 90.000 U ncontrolledR eceive Antenna Pointing Loss Lpr dB -9.720R eceive Antenna G ain G r dB -12.241
CUBESATComm. System
System N oise Tem perature Ts dB K 31.100D ata R ate R bps 1200.000Eb Eb0 dB 32.634B it Er B ER 0.000
R equired Eb/N 0 R eq Eb/N 0dB -H z 13.000 FSK,B ER =10-5
y
69Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
R equired Eb/N 0 R eq Eb/N 0dB H z 13.000 FSK, B ER 10Im plem ention Loss dB -5.000M argine dB 14.634
Communications Examples Communications Examples –– QuakesatQuakesat
QuakeSat Tasking & Data Flow ConceptQuakeSat Tasking & Data Flow Concept
Research TasksNORAD Tracking
Health Files
Mission Data FilesAX.25 Protocol
RequestsResults
NORAD Tracking2 line element sets
Uplink
Additional Ground Stanford
G d Q k Fi d
Tasking Files,New Software
FTP FilesStations
(Fairbanks)Ground Station
(unmanned)
QuakeFinderMission Control
Center (MCC)
FTP Files
Internet Control
70Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
MCS Components
Communication Examples Communication Examples –– QuakesatQuakesat
DeployableRadio Antennas
M t tMagnetometerDeployablesolar panels Deployablep y
2-section boom
1 foot 1 foot 2 feet
Total weight = 9 9 lbs (4 5 kg)
71Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Total weight = 9.9 lbs (4.5 kg)
Communications Examples Communications Examples –– QuakesatQuakesat
CommunicationCommunication
• 9600 baud, AX.25 packet system• Stanford developed a customized version with PFR/PFS to
handle packet control of long files (fill holes)handle packet control of long files (fill holes)• Typical magnetometer and housekeeping file length is 100‐
300kB L t fil i kB– Longest file in one pass: 700kB
– Avg. 8 magnetometer collects per day (1 MB)• Beacon every 10 sec. (disabled w/ mag. collects)y g
– 33 data points plus time and date• Stanford Ground Station (SGS)
Access via Internet remote controlled standardized I/F– Access via Internet, remote controlled, standardized I/F– 15 db Yagi, auto antenna control using El Sets– New features being added, (polarity control, signal strength)
72Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
PPPowerPowerSubsystemSubsystemSubsystemSubsystem
73Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power SubsystemPower Subsystem
ObjectivesObjectivesProvide a stable and reliable energy supply to all the S/C subsystems andProvide a stable and reliable energy supply to all the S/C subsystems andpayloads during all the mission life. For this to be done the Power subsystemshall:
• Generate and store electric energy to be supplied to other S/C subsystems• Control the electric current flow:
– To the secondary energy source (batteries)– To be distributed to the S/C subsystems
• Distribute the electric power.• Adapt the current to the different equipments requirements.• Autonomous power management during Sun-Eclipse transitions.• Protect all the electric and electronic equipments against power failures or
system degradation.
74Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power SubsystemPower Subsystem
Power subsystem components (I/II)Power subsystem components (I/II)
Primary energy source Power distribution, control and main bus protection
Power source
Power conversion
Charge control Discharge bypass
Source control
Load
s
Secondary energy source
Shunt voltage limiter Regulation
wer
con
ditio
ning
Energy storage
Secondary energy source
Pow
Energy storage control
75Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power SubsystemPower Subsystem
Primary energy source
Power subsystem components (II/II)Power subsystem components (II/II)
Power source
Primary energy source
• Solar radiation• Chemical energy• Nuclear energy
Power conversion
Source control
gy
• Solar cell arrays• Fuel cells• RTG in
g
Secondary energy source
Pow
er c
ondi
tion
• DC-DC Converters• DC-AC Converters• Current/Voltage
adaptors
Energy storage • Batteries• Fuel cells
P adaptors
Energy storage control
76Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power SubsystemPower Subsystem
Average versus peak powerAverage versus peak power
Power (W)
300300 W Peak Power
200
100 90 W Average Power
1 2 3 4 5 6 7 8 9 10 T (Hours)
77Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power SubsystemPower Subsystem
Typical power requirementsTypical power requirements
T Average power P k (kW)Type g p(kW) Peak power (kW)
Pico satellites ~10‐3 ~10‐3
Micro satellites 10‐3 – 10‐1 0.1 – 0.2
Small satellites 0.1 – 0.3 0.2 – 0.43
Comm. Satellites (GEO) 1.5 – 5.5 2.0 – 6.5
C S t llit (LEO) 8 Comm. Satellites (LEO) 0.5 ‐ 0.8 0.7 – 1.2
Remote sensing 2.0 – 6.5 2.8 – 8.7
I l b Interplanetary probes 0.3 – 0.5 0.8 – 1.0
Space shuttle 10 ‐ 15 13 ‐ 17
78Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Space platforms 25 ‐ 110 50 ‐ 150
Manned Mars mission 2000 ‐ 4000
Power SubsystemPower Subsystem
Power subsystems evolutionPower subsystems evolution
79Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power SubsystemPower Subsystem
Design requirementsDesign requirements
• In-orbit autonomous and continous power supply to S/C equipmentsand payloads.
• A t t d i S E li t iti• Autonomous power management during Sun-Eclipse transitions.• Simplicity in power interface with the loads.• High reliability applying modular design and redundanciesHigh reliability, applying modular design and redundancies.• Protection against failures and degradation.• Minimum mass to optimise the charge capacity.p g p y• Minimum recurring cost.• Bus voltage compatible with existing equipments and payloads.
80Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power SubsystemPower Subsystem
Design drivers (I/II)Design drivers (I/II)• Mission
– Client / Final user– Distance to Sun– Manouvering
• Orbital parameters– Altitude– InclinationManouvering
• Vehicle configuration– Mass restrictions– Size
– Eclipse cycles• Payload requirements
– Power, voltage and currentD t l k– Launch vehicle imposed restrictions
– Thermal dissipation capacity• Duty cycle
T t l i i lif ti
– Duty cycle, power peaks– Protection against failures
– Total mission lifetime– Power levels in different modes– Power levels during different mission phases
• Attitude controlAttitude control– Spinning S/C– 3-Axis stabilisation– Pointing requirements
81Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
– Thrusters position
Power SubsystemPower Subsystem
Design drivers (II/II)Design drivers (II/II)
82Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power SubsystemPower Subsystem
Preliminary design process for the Power SubsystemPreliminary design process for the Power SubsystemStep Information Required Derived Requirements
1. Identify requirements
Top‐level requirements, mission type (LEO, GEO), spacecraft configuration, mission life,
Design requirements, spacecraft electrical power profile (average
d k)configuration, mission life, payload definition and peak)
S l t d i
Mission type, spacecraft configuration, average load
EOL power requirement, type of solar cell, mass and area of solar
l fi ti (2. Select and size power source g , grequirements for electrical requirements
array, solar array configuration (2‐axis tracking panel, body‐mounted)
Eclipse and load‐leveling enerfy
3. Select and size energy storageMission orbital parameters, average and peak load requirements for electrical power
Eclipse and load‐leveling, enerfy storage requirement (battery capacity requirement), battery mass and volume, battery type
4. Identify power regulation and control
Power source selection, mission life, requirements for regulating mission load, thermal control requirements
Peak‐power tracker or direct‐energy‐transfer system, thermal‐control requirements. Bus‐voltage quality power control algorithms
83Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
requirements quality, power control algorithms
Power SubsystemPower SubsystemEffects of systemEffects of system--level parameters on the Power Subsystemlevel parameters on the Power Subsystem
Parameter Effects on designg
Average electrical power requirement
Sizes the power generation system (e.g., number of solar cells, primary battery size) and possibly the energy storage system given the eclipse period and depth of discharge
Peak electrical power required
Sizes the energy storage system (e.g., number of batteries, capacitor bank size) and the power processing and distribution equipment
Mission lifeLonger mission life (>7 yr) implies extra redundancy design, independent battery charging, larger capacity batteries and larger arrays
Orbital parameters Defines incident solar energy, eclipse/Sun periods and radiation environment
Spacecraft configurationSpinner typically implies body‐mounted solar cells; 3‐axis stabilised typically implies body‐fixed and deployable solar panels
84Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
p
Power SubsystemPower Subsystem
Common spacecraft power sources comparisonCommon spacecraft power sources comparisonEPS Design P t Solar photovoltaic Radio‐isotope Fuel cellParameters p p
Power range [kW] 0.2 ‐ 300 0.2 ‐ 10 0.2 ‐ 50
Specific power [W/kg] 25 ‐ 200 5 ‐ 20 275
Specific cost [$/W] 800 – 3000 16K – 200K Insufficient data
Low‐orbit drag High Low Low
Degradation over life Medium Low Low
Storage required for solar eclipse Yes No No
Sensitivity to Sun angle Medium None None
Sensitivity to S/C shadowing Low (with bypass diodes) None None
Obstruction of S/C Hi h L N/viewing High Low None
IR signature Low Medium Medium
Principal applications Earth‐orbiting spacecrafts Inter‐planetary Manned missions
85Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Principal applications Earth orbiting spacecrafts Inter planetary Manned missions
Power SubsystemPower Subsystem
Issues in designing the energy storage capacityIssues in designing the energy storage capacity
Issue Effects on design
Physical Size, weight, configuration, operating position, static and dynamic environments.
Electrical Voltage, current loading, duty cycles, activation time and storage time and limits on depth of discharge.
Programmatic Cost, shell and cycle life, mission, reliability, maintainability and produceability.
86Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power SubsystemPower Subsystem
Solar photovoltaicSolar photovoltaic
Pout = Pin· ·cos ()
• Pout : Solar cell’s output power density (W/m2)
• Pin : Incoming solar power density (W/m2)
• : Solar cell’s energy conversion efficiency
• : Incidence angle (deg or rad)
87Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power SubsystemPower Subsystem
Solar cell efficiencySolar cell efficiencyCell type Theoretical efficiency Achieved efficiencyCell type Theoretical efficiency Achieved efficiency
Thin sheet Amorphus Si 12 % 5 %
14 8 %Silicon (Si) 20.8 % 14.8 %
Gallium Arsenide (GaAs) 23.5 % 18.5 %
GaAs/Ge 19 % N/A
Indium Phosphide 22.8 % 18 %
Multijunction (GaInP/GaAs) 25.8 % 22 %
• Energy to solar array area for Si: ≈ 120 – 210 W/m2
• Energy to solar array area for GaAs: ≈ 170 – 260 W/m2
88Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power SubsystemPower Subsystem
1. Determine requirements and constrains for power subsystem solar array
Solar array design processSolar array design process1. Determine requirements and constrains for power subsystem solar array
design:• Average power required during daylight and eclipses• Orbit altitude and duration• Design lifetime
2. Calculate amount of power that must be produced by the solar arrays3. Select type of solar cell and estimate power output with the Sun normal to the3. Select type of solar cell and estimate power output with the Sun normal to the
surface of the cells4. Determine the beginning of life (BOL) power production capability per unit area
of the array5. Determine the end of life (EOL) power production capability for the solar array6. Estimate the solar array area required to produce the necessary power based
on EOL power and alternate approach7. Estimate the mass of the solar array8. Document assumptions
89Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Taller de Diseño Preliminar de Satélites, Escuela Técnica Superior de Ingenieros Aeronáuticos, 2009
© SENER Ingeniería y Sistemas S.A. Proprietary Information
Power SubsystemPower Subsystem
Solar array design processSolar array design process
90Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power SubsystemPower Subsystem
BatteriesBatteries
• Batteries store electrical energy in the form of chemical energy.• Spacecraft use two kind of batteries:
Primary batteries: Designed for single use for short missions (less than one month)and firing of pyrotechnic devices. Can’t be recharged by reversing the dischargecurrent flow (e.g. Silver Zinc).
Secondary batteries: Can be discharged and recharged several times. Use as partof the main power system to supply the load during eclipse and whenever the loadexceeds the solar array capability (e g NiCd NiH2)exceeds the solar array capability (e.g. NiCd, NiH2).
• Eclipse time, design life and average power requirements drive storage capacityrequirement.q
• Depth-of-discharge and number of discharge cycles determine available capacity.
91Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Taller de Diseño Preliminar de Satélites, Escuela Técnica Superior de Ingenieros Aeronáuticos, 2009
© SENER Ingeniería y Sistemas S.A. Proprietary Information
Power SubsystemPower Subsystem
BatteriesBatteries
92Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power SubsystemPower Subsystem
Characteristics of primary batteriesCharacteristics of primary batteries
Primary battery couple
Specific energy density
[W h /k ]Typical applicationp [W∙hr/kg]
Silver Zinc 60 ‐ 130 High rate, short life (minutes)
Lithium Thiorryl Medium rate moderate life (< 4 Lithium Thiorryl Chloride 175 – 440 Medium rate, moderate life (< 4
hours)
Lithium Sulfur Dioxide 130 350 Low/medium rate long life (days)Dioxide 130 – 350 Low/medium rate, long life (days)
Lithium M fl id 130 – 350 Low rate, long life (months)Monofluoride 3 35 , g ( )
Thermal 90 ‐ 200 High rate, very short life (minutes)
93Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power SubsystemPower Subsystem
Characteristics of secondary batteriesCharacteristics of secondary batteries
Secondary battery couple Specific energy density[W∙hr/kg] Status
Nickel‐Cadmium 25 ‐ 30 Space‐qualified, extensive database
Nickel‐Hydrogen (individual pressure vessel design)
35 – 43 Space‐qualified, good database
Nickel‐Hydrogen (common pressure vessel design)
40 – 56 Space‐qualified for GEO and planetary
Nickel‐Hydrogen (single S lifi dNickel Hydrogen (single pressure vessel design) 43 – 57 Space‐qualified
Lithium‐Ion (LiSO2, LiCF, LiSOCl2)
70 ‐ 110 Under development
Sodium‐Sulfur 140 ‐ 210 Under development
94Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power SubsystemPower Subsystem
Characteristics of secondary batteriesCharacteristics of secondary batteries
95Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power SubsystemPower Subsystem
Steps in the energy storage subsystem designSteps in the energy storage subsystem design
1. Determine the energy storage requirements. Consider:• Mission length• Primary and secondary power storage• Primary and secondary power storage• Orbital parameters (eclipse frequency, eclipse length)• Power use profile (voltage and current, DOD, duty cycles)• B tt h /di h l li it• Battery charge/discharge cycle limits
2. Select the type of secondary batteries3. Determine the size of the batteries (batteries capacity):
• N b f b i• Number of batteries• Transmission efficiency between the battery and the load
Battery capacity (for battery capacity in Amp-hr, divide by bus voltage)
hrWTPC ee ··
96Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
hrWnNDOD
Cr ··
Power SubsystemPower Subsystem
Steps in the energy storage subsystem designSteps in the energy storage subsystem design
97Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power SubsystemPower Subsystem
1 Determine the electrical load profile Consider:
Steps in the power distribution subsystem designSteps in the power distribution subsystem design1. Determine the electrical load profile. Consider:
• All spacecraft loads, their duty cycles and special operation modes• Inverters and arc requirements• Transient beha ior ithin each load• Transient behavior within each load• Load-failure isolation
2 D id t li d d t li d t l2. Decide on centralised or decentralised control:• Transient behaviour within each load• Total system mass
3. Determine the fault protection subsystem:• Detection (active or passive)• Isolation• Correction (change devices, reset fuses, work around lost subsystem)
98Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power SubsystemPower Subsystem
Steps in the power regulation and control subsystem designSteps in the power regulation and control subsystem design
1. Determine the power source. Consider:• All spacecraft loads, their duty cycles and special operation modes (primary
batteries, photovoltaic, static power, dynamic power)2. Decide the electrical control subsystem:
• Power source• Battery charging (peak power tracking, direct energy transfer)• Spacecraft heating
3. Develop the electrical bus voltage control:• How much control does each load require? (unregulated, quasi-regulated, fully
regulated)• Battery voltage variation from charge to discharge• Battery recharge subsystem (parallel or individual charging, < 5yrs – parallel
charge, >5yrs – independent charge)• Battery cycle life
99Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
• Total system mass
Power Examples Power Examples –– Generic CubesatsGeneric Cubesats
DeployableRadio Antennas
M t tMagnetometerDeployablesolar panels Deployablep y
2-section boom
100Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power Examples Power Examples –– Generic CubesatsGeneric Cubesats
DeployableRadio Antennas
M t tMagnetometerDeployablesolar panels Deployablep y
2-section boom
101Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power Examples Power Examples –– XIXI--IVIV
ChargeCi i
DeployableRadio Antennas
AAAA
CircuitA A
M t t
AAAAAAAAAAAAAA TNC OBC OBC
MagnetometerDeployablesolar panels Deployable
Batteries SwitchingRegulator
SwitchingRegulator
DCDCConverterp y
2-section boomRegulator Regulator Converter
Electronics CommunicatiS b
Tx
102Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Subsystem on Subsytem
Power Examples Power Examples –– XIXI--IVIV
Power Regulation & ControlPower Regulation & Control
• Bus voltage: main 5[V]• Regulated to 5V using switching
regulators and DCDC converter regulators and DCDC converter • Elect. subsystem power line &
Comm. subsystem power lines y pare independent so that they monitor each other and shutdown in case of SELshutdown in case of SEL
103Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
SourceSource
• Power is supplied by body mounted solar cells.• Cells are arranged on all 6 CubeSat surfaces• Cells are arranged on all 6 CubeSat surfaces.• Average power 1228 [mW] (typ @ 80 )
104Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power Examples Power Examples –– XIXI--IVIV
Solar PanelSolar Panel
Bass bar
■Cell type : Si Crystal (SHARP)■Efficiency : 16%■10 cells in series / panel■Cell size:■Cell size:
+X :28.25x13.8mm-X,+Y,-Y:47.75x13.8mm+Z Z 47 75 15 8+Z,-Z :47.75x15.8mm
105Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Photo:3 cells in series
Power Examples Power Examples –– XIXI--IVIV
Solar Array Layout (+X panel)Solar Array Layout (+X panel)
+X panel:
4.5V x 172mA = 774mW(typ @ 25 )(typ. @ 25 )
4.5V x 162mA = 727mW(typ. @ 80 )
106Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power Examples Power Examples –– XIXI--IVIV
Solar Array Layout (Solar Array Layout (--X,+Y,X,+Y,--Y panel)Y panel)
-X,+Y,-Y panels:
4.5V x 297mA = 1336mW(typ @ 25 )(typ. @ 25 )
4.5V x 279mA = 1256mW(typ. @ 80 )
107Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power Examples Power Examples –– XIXI--IVIV
Solar Array Layout (+Z,Solar Array Layout (+Z,--Z panel)Z panel)
+Z,-Z panels:, p
4.5V x 340mA = 1530mW(t @ 25 )(typ. @ 25 )
4.5V x 319mA = 1438mW(typ. @ 80 )( yp @ )
108Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power Examples Power Examples –– XIXI--IVIV
Energy StorageEnergy Storage
• Batteries will be used during eclipse and downlinkLii d b i • Liion secondary batteries are selected.
• 8 batteries are set in parallel8 batteries are set in parallel.• DOD is 3%• Batteries only lifetime is 38 hrsBatteries only lifetime is 38 hrs
109Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Power Examples Power Examples –– XIXI--IVIV
Liion batteryLiion battery
Cathode Material Lithium Manganate
A d M i l C bAnode Material Carbon
Operating Voltage 3 8[V]Operating Voltage 3.8[V]
Discharge Capacity 780 [mAhr]Discharge Capacity 780 [mAhr]
Single Cell Spec
110Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Single Cell Spec.
Power Examples Power Examples –– XIXI--IVIV
Battery ChargerBattery Charger• 3 candidates for Battery Charge Circuit3 candidates for Battery Charge Circuit
MAX1679 MM1333 MM1485MAX1679 MM1333 MM1485
•Small package (8 pins), •Small package (8 pins), •Small power dissipation•Const. Voltage &
small power dissipation•Voltage&Temperature protection
small power dissipation•Const. Voltage & Current Charge Mode
gCurrent Charge Mode•Pre-charge Temperature protectionp
•Pre-charge, Timeout
•Need constant reset
g
•No pre-charge func or temperature protection
Temperature protection
•Large package (16 pins) and may be difficult to
111Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Need constant reset before IC’s timeout
temperature protection and may be difficult to assembly
Power Examples Power Examples –– XIXI--IVIV
Energy ConsumptionEnergy Consumption
Components Power[mW] Frequency in use
OBC 20 All timessensors 20 All timesTx TNC 20 During downlinkTx 6000 During downlinkCW 300/125 All times (ON / OFF)CW TNC 20 All timesR 125 All iRx 125 All timesRx TNC 20 All timesCamera 150 Sometimes
112Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Camera 150 SometimesMagnetic Plg. 800 Antennae deployment
Power Examples Power Examples –– XIXI--IVIV
Power BalancePower Balance
P i t• Points– Beacon can be sent by solar panels direct drive
Source and consumption must be balanced– Source and consumption must be balanced
• Solar cell average output 1228[mW] > Consumption at beacon use 900[mW]beacon use 900[mW]
• Maximum average supply power: 669[mW] > Average • Maximum average supply power: 669[mW] > Average consumption 616[mW] OK
113Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
OK
Power Examples Power Examples –– QuakesatQuakesat
DeployableRadio Antennas
M t tMagnetometerDeployablesolar panels Deployablep y
2-section boom
1 foot 1 foot 2 feet
Total weight = 9 9 lbs (4 5 kg)
114Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Total weight = 9.9 lbs (4.5 kg)
St tSt tStructureStructureSubsystemSubsystemSubsystemSubsystem
115Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Structure SubsystemStructure Subsystem
ObjectivesObjectives
• Main functions of the structure subsystem:– Mechanically support all other spacecraft subsystems– Attaches the spacecraft to the launcher– Provides for ordnance‐activated separation
All tiff d t th i t– All stiffness and strength reuirements– Interfaces with booster
• T o elements• Two elements:– Primary structure, supporting major loads– Secondary structure for auxiliary elements weighting less – Secondary structure, for auxiliary elements weighting less
than 5kg
116Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Structure SubsystemStructure Subsystem
Structure Design ProcessStructure Design ProcessEnvelope
Accessibility
MissionLaunchVehicle
Environments
SubsystemRequirements
EnvelopeProducibility
Define Load Paths
Definition of requirementsDevelopment of configurations
Definition of Design OptionsDefinition of Test/Analysis
TestCriteria
DesignC i i
Construction Material
CriteriaCriteria
Options Options
Sizing and checkingi t
117Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
requirements Detailed Design
Structure SubsystemStructure Subsystem
Main RequirementsMain Requirements
All Ph f f h d Mission PhaseMission Phase Source of RequirementsSource of Requirements• All Phases, from manufacture to the end of the mission
Mission PhaseMission Phase Source of RequirementsSource of Requirements
Manufacture and Assembly
•Handling fixture or container reactions• Stressess induced by manufacturing processes (welding)
Transport and dli
• Crane or dolly reactionsHandling • Land, sea or air transport environments
Testing • Environments from vibration or acoustic tests• Test fixture raction loads
Prelaunch •Handling during stacking sequence and pre‐flight checksPrelaunch Handling during stacking sequence and pre flight checks
Launch and Ascent
• Steady‐state booster accelerations• Vibro‐acoustic noise during launch and transonic phase• Propulsion system engine vibrationsT i l d i hi l ll l h d l d f i i • Transient loads, stage separations, vehicle manoeuvres, propellant slosh and payload fairing
separation• Pyrotechnic shock from separation events, deployments• Thermal environments
Mi i S d h l iMission operations
• Steady‐state thruster accelerations• Transient loads during attitude manoeuvres and attitude control burns or docking events• Pyrotechnic shocks from separation events, deployments• Thermal environments
118Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Reentry and Landing
• Aerodynamic heating• Transient wind and landing loads
Structure SubsystemStructure Subsystem
Main RequirementsMain RequirementsS/CS/C
Allowable Weight driven by:Allowable Weight driven by:•• LauncherLauncher
O bitO bitS/CS/CWeightWeight
•• OrbitOrbit•• Upper StageUpper Stage•• Weight growthWeight growth
S/CS/CSizeSize
Allowable Size driven by:Allowable Size driven by:•• Launcher fairingLauncher fairing
LaunchLaunchVehicleVehicle
S/CS/CS/CS/CRigidityRigidity
Required Rigidity driven by:Required Rigidity driven by:•• Avoiding natural frequenciesAvoiding natural frequencies
S/CS/CStrengthStrength
Required Strength driven by:Required Strength driven by:•• SteadySteady--state accelerations state accelerations (load factors)(load factors)•• Random/Acoustic vibrationRandom/Acoustic vibration
119Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
StrengthStrength •• Random/Acoustic vibrationRandom/Acoustic vibration•• Shock levelsShock levels
Structure SubsystemStructure Subsystem
Development of the Configuration Development of the Configuration -- ConstraintsConstraints
AOCS:AOCS:•• StabilizationStabilization
Payload:Payload:•• AccomodationAccomodation
TTC Antennae:TTC Antennae:•• RigidityRigidity
•• SensorsSensors •• SizeSize •• Thermoelastic stabilityThermoelastic stability•• Clear FoVClear FoV
StructureStructure
OBDH:OBDH:•• Radiation shieldingRadiation shielding
Wi i l thWi i l th
Concurrent design:Concurrent design:•• WiringWiring•• PipingPiping
•• Wiring lengthWiring length
Propulsion:Propulsion:
•• Components distributionComponents distribution
Propulsion:Propulsion:•• Engine modulesEngine modules•• PeripheryPeriphery
N t i tiN t i ti
Power:Power:•• Stowed S/AStowed S/A
Thermal:Thermal:•• ComponentsComponents
120Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
•• No contaminationNo contamination•• Batteries accessBatteries access
Components Components distributiondistribution
Structure SubsystemStructure Subsystem
Design optionsDesign options
Methods of Methods of constructionconstruction
MaterialsMaterials Type of Type of structurestructure
Trade Trade
structurestructure
StudiesStudies
WeightWeight CostCost RiskRisk
121Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
gg
Structure SubsystemStructure Subsystem
Design optionsDesign options Methods of Methods of t tit ti
Methods of construction:Methods of construction:constructionconstruction
Type ofType ofMaterials:Materials:Type of structure:Type of structure:
•• FoldingFolding•• MachiningMachining•• AdhesivesAdhesives•• WeldingWelding
MaterialsMaterials Type of Type of structurestructure
•• StrengthStrength•• StiffnessStiffness•• Density (Weight)Density (Weight)
Th l d ti itTh l d ti it
Type of structure:Type of structure:•• Skin panel assembliesSkin panel assemblies•• TrussesTrusses•• Ring framesRing frames
•• WeldingWelding•• FastenersFasteners
•• Thermal conductivityThermal conductivity•• Thermal expansionThermal expansion•• Corrosion resistanceCorrosion resistance•• CostCost
•• Ring framesRing frames•• Pressure vesselsPressure vessels•• FittingsFittings•• BracketsBracketsCostCost
•• Ductility (can prevent Ductility (can prevent cracks)cracks)•• Fracture toughnessFracture toughness
•• Equipment boxesEquipment boxes
•• MonocoqueMonocoque•• Ease of fabricationEase of fabrication•• Versatility of attachment Versatility of attachment options (welding)options (welding)•• AvailabilityAvailability
•• SemimonocoqueSemimonocoque•• SkinSkin--stringerstringer•• SandwichSandwich
122Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
AvailabilityAvailability
Structure SubsystemStructure Subsystem
Material selection (I/II)Material selection (I/II)• MaterialMaterial AdvantagesAdvantages DisadvantagesDisadvantages
Aluminium •High strength vs weight•Ductie; tolerant of concentrated stresses• Easy to machine• Low density; efficient in compression
• Relatively low strength vs volume• Low hardness•High coefficient of thermal expansion
Steel •High strength•Wide range of strength, hardness and ductility obtained by treatment
• Not efficient for stability (high density)•Most are hard to machine•Magnetic
Heat‐i t t
•High strength vs volume • Not efficient for stability (high density)resistant • Strength retained at high temperatures
•Ductile• Not as hard as some steels
Magnesium • Low density, very efficient for stability • Susceptible to corrosion• Low strength vs volume
Titatium • High strength vs weight• Low coefficient of thermal expansion
•Hard to machine• Poor fracture toughness if solution treated and aged
Beryllium •High stiffness vs density • Low ductility & fracture toughness• Low short transverse properties• Toxic
Composite • Tailored for high stiffness, high strength and extremely low coefficient of thermal expansion• Low density• Good in tension (eg pressurised tanks)
• Costly for low production volume, requires development programme• Strength depends on workmanship, ussually requires individual proof testing
123Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
• Good in tension (eg, pressurised tanks) proof testing• Laminated composites are not as strong in compression• Brittle, can be hard to attach
Structure SubsystemStructure Subsystem
Material selection (II/II)Material selection (II/II)•
E/ E1/2/ E1/3/ f/Al 6061 T6 2700 68 276 24 2 9 1 5 98 6 23 6 186 97
Material Density(kg/m3)
Young's ModulusE(GPa)
Yield Strengthf(Mpa)
Thermal expansion(m/m K-1)
Fracture toughness
(MPa m)
Fatigue Strength
(MPa)
Selection criteria
Al 6061 T6 2700 68 276 24 2,9 1,5 98,6 23,6 186 97Al 7075 T6 2800 71 503 26 3,1 1,5 186,3 23,4 24 159Mg A2 31B 1700 45 220 26 3,9 2,1 129,4 26Mg ZK 60 A.T5 1700 45 234 26 3,9 2,1 137,6 26 124Ti 6Al 4V 4400 110 825 25 2 4 1 1 187 5 9 75 500Ti-6Al-4V 4400 110 825 25 2,4 1,1 187,5 9 75 500Be S 65 A 2000 304 207 151 8,7 3,4 103,5 11,5Be SR 200 E 2000 304 345Fe INVAR 150 275/415 1,66Fe AM 350 (SCT850) 7700 200 1034 26 1 84 0 8 134 3 11 9 40/60 550Fe AM 350 (SCT850) 7700 200 1034 26 1,84 0,8 134,3 11,9 40/60 550Fe 304L Ann 7800 193 170 25 1,8 0,7 21,8 17,2KEVLAR 49 0º 1380 76 1379 55 6,3 3,1 999,3 -4Aramid fibre 90º 1380 5,5 29,6 4 1,7 1,3 21,4 57Graphite epoxy 1620 282 586 174 10 4 4 361 7 -11 7/29 7Graphite epoxy 1620 282 586 174 10,4 4 361,7 -11,7/29,7
MIL-HDBK-5, “Metallic Materials and Elements for Aerospace Vehicle Structures”
124Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Structure SubsystemStructure Subsystem
Design philosophyDesign philosophy
LightnessLightness AffordabilityAffordability
ReliabilityReliability
Material strength:Material strength: Loads:Loads:
UncertaintiesUncertainties
•• RandomRandom•• Undetectable flawsUndetectable flaws•• Process variationsProcess variations
•• AcousticsAcoustics•• Engine vibrationEngine vibration•• Air turbulenceAir turbulence
125Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
UncertaintiesUncertainties
Structure SubsystemStructure Subsystem
Design philosophyDesign philosophy
TermTerm DefinitionDefinition
Load Factor • A multiple of weight on Earth, representing the force of inertia that resists acceleration
Limit Load • The maximum load expected during the mission at a specified or selected statistical probability
Allowable Load or • The highest load or stress a structure or material can withstand Stress without failure, based on statistical probability
Factor of Safety • A factor applied to the limit load to obtain the design load for the purpose of decreasing the chance of failure
Design Load • Limit load multiplied by the yield or ultimate factor of safety. Thisvalue must be no greater then the corresponding allowable load
Design Stress • Predicted stress caused by the design load This value must not Design Stress • Predicted stress caused by the design load. This value must not exceed the corresponding allowable stress
Margin of Safety • A measure of reserve strength: Allowable load/Design load – 1 ≥0
126Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Structure SubsystemStructure Subsystem
Design philosophyDesign philosophy
OptionOption Design Factors of Design Factors of SafetySafety
YieldYield UltimateUltimate
Ultimate test of dedicated qualification article (1.25xlimit) 1.0 1.25
f f ll fl h ( l )Proof test of all flight structures (1.1xlimit) 1.1 1.25
Proof test of one flight unit of a fleet (1.25xlimit) 1.25 1.4
No structural test 1.6 2.0
127Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Structure SubsystemStructure Subsystem
Preliminary SizingPreliminary Sizing
StrengthStrengthSt e gtSt e gt
StiffnessStiffness WeightWeight
Preliminary Preliminary SizingSizinggg
128Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Structure Examples Structure Examples –– Generic CubesatsGeneric Cubesats
129Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Th lTh lThermalThermalSubsystemSubsystemSubsystemSubsystem
130Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Thermal SubsystemThermal Subsystem
Objectives• The role of the Thermal Control Subsystem (TCS) is to maintain all• The role of the Thermal Control Subsystem (TCS) is to maintain all
spacecraft and payload components and subsystems within theirrequired temperature limits for each mission phase:• Operational limits• Operational limits• Survival limits
• TCS is also used to ensure that temperature gradient requirements aremet in order to avoid any structural deformation and avoid pointingerrors.
The biggest problem is getting rid of excess heat
131Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Thermal SubsystemThermal Subsystem
Design drivers (I/II)Design drivers (I/II)• The environment in which the spacecraft
Heat fluxes and not temperatures
• The environment in which the spacecrafthas to operate
• Th t t l t f h t di i t d are the subject of control• The total amount of heat dissipated onboard the spacecraft
• The distribution of the thermaldissipation inside the spacecraft
• Th t t i t f th• The temperature requirements of thevarious equipment items
• The config ration of the spacecraft and• The configuration of the spacecraft, andits reliability/verification requirements
132Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Thermal SubsystemThermal Subsystem
Design drivers (II/II)Design drivers (II/II)
133Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Thermal SubsystemThermal Subsystem
Thermal environment for a LEO SpacecraftThermal environment for a LEO SpacecraftR di i S
Direct solar radiation
Radiation to Space
(1358±5 W/m2)
Reflected sunlight
(30±5 W/m2)
Radiation from Earth
(237±21 W/m2)
Power generated in the S/C
134Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Thermal SubsystemThermal Subsystem
Typical thermal requirements for spacecraft componentsTypical thermal requirements for spacecraft components
ComponentTypical temperature ranges [ºC]
Operational Survival
Batteries 0 to 15 ‐10 to 25
Power box baseplates ‐10 to 50 ‐20 to 60
R ti h l t t Reaction wheels ‐10 to 40 ‐20 to 50
Gyros/IMUs 0 to 40 ‐10 to 50
Star trackers 0 to 30 ‐10 to 40Star trackers 0 to 30 10 to 40
Hydrazine tanks and lines 15 to 40 5 to 50
Antenna Gimbals ‐40 to 80 ‐50 to 90
Antennas ‐100 to 100 ‐120 to 120
Solar panels ‐150 to 110 ‐200 to 130
135Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Thermal SubsystemThermal Subsystem
Typical installed powers for various kinds of spacecraft Typical installed powers for various kinds of spacecraft
136Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Thermal SubsystemThermal Subsystem
Radiation heat transfer: influence of surface propertyRadiation heat transfer: influence of surface property
Incident radiationRefelected radiation
Absorved radiation
Transmitted radiation
1
The steady state temperatures withdifferent surface coatings:
41
2··4····4·
RPST
137Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Thermal SubsystemThermal Subsystem
Radiation equilibrium temperatureRadiation equilibrium temperature• The spacecraft skin temperature or radiation equilibrium temperature can be
calculated from the basic heat balance equation.• However:
• Orbital data (altitude and orientation relative to external heat sources) andOrbital data (altitude and orientation relative to external heat sources) and• Detailed spacecraft configuration need to be known
Heat In + Internal Heat = Heat Out Radiation equilibrium temperature
• Varying orbit conditions and power dissipation together with complex• Varying orbit conditions and power dissipation together with complexconfigurations require thermal analyses codes:• ESATAN• ESARAD• SINDA• RadCAD
138Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Thermal SubsystemThermal Subsystem
Thermal control system design process (I/II)Thermal control system design process (I/II)
Step Inputs Outputs Key issues
1. Identify thermal C t th l ‐ System thermal requirements ‐ Identify payload thermal requirementsyrequirements and constrains
Component thermal requirements
y q‐ Specialised requirements for specific equipment
y p y q‐ Identify major elements that may present thermal challenges (see step 3)
2. Determine ‐ Orbit/attitude history ‐Total energy input to the S/C‐Max & min distances to Sun‐Max & min distance to Earth or other central thermal
environment‐ S/C size and shape‐ Internal heat sources
Total energy input to the S/C‐ Profile of energy input vs. time
Max & min distance to Earth or other central body‐ Chemical or nuclear internal heat sources
3 Identify thermal ‐ Thermal requirements List of specific thermal problem
Identify major elements that:‐ Generate large amounts of heat‐ Need cryo operating temperatures3. Identify thermal
challenges or problem areas
‐ Heat sources‐ Equipment placement and attitude history
List of specific thermal problem areas or problem times or events (hot, cold or stability)
Need cryo operating temperatures‐ Have boiling or freezing problems‐ Require a narrow temperature rangeIdentify extraordinary thermal events or actions
‐ Prefer passive over active means
4. Identify applicable thermal control techniques
‐ Thermal requirements and energy profile from above‐ Additional constrains
‐ Preliminary list of thermal control mechanisms for mission duration and principal S/C components, areas or times
Prefer passive over active means‐ Component placement often key‐ Pay particular attention to problem areas or severe thermal constrains‐Watch for mission critical issues (freezing propellant or hinge; fluid boiling or potential
l i )
139Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
explosions)
Thermal SubsystemThermal Subsystem
Thermal control system design process (II/II)Thermal control system design process (II/II)
Step Inputs Outputs Key issues
‐List of thermal T k i
5. Determine radiator and heater
List of thermal environments & events‐ Thermal control approach
‐ Radiator sizes and temperatures to manage hot case with marginH f ld
Take into account:‐Degradation of thermal surfaces over mission life‐ Longest eclipse furthest from a
l b dheater requirements
approach‐ Components temperature requirements
‐ Heater power for cold case thermal control
warm central body‐‐ Extraordinary thermal events or circumstances
6 E ti t T i ll % t % f d 6. Estimate TCS mass and power
‐ List of TCS methods and components
‐ TCS mass‐ TCS power
‐ Typically 2% to 10 % of dry mass‐May impact mass & power of other subsystems
7 Document Thermal robustness can be key to 7. Document and iterate
ysystem design flexibility and reducing operations cost
140Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Taller de Diseño Preliminar de Satélites, Escuela Técnica Superior de Ingenieros Aeronáuticos, 2009
© SENER Ingeniería y Sistemas S.A. Proprietary Information
Thermal SubsystemThermal Subsystem
Thermal design development process IThermal design development process ILIST DESIGN REQUIREMENTSLIST DESIGN REQUIREMENTSPayload requirements usually dominates the design
BASELINE DESIGNMass
ESTABLISH HEAT INPUT SOURCESSun, Earth, electronics…
COMPUTE WORST-CASE HOT AND
SizePower
NO YES
COLD TEMPERATURES
SELECT THERMAL CONTROL TECHNIQUETECHNIQUE
DETERMINE HEATER POWER REQUIRED
MEET REQS?
COMPARE WORST-CASE VALUES WITH DESIGN TEMPERATURE LIMITS
141Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Thermal SubsystemThermal Subsystem
Design requirementsDesign requirements• Temperature limits and reliability requirements for each component• Equipment power dissipations and operating modes• Range of mission orbit parameters• Operationl satellite attitudes• Attitudes during stressed or failure modesg• Launch phase configurations and attitudes• Ground cooling needs• Autonomy requirements• Thermal-distrotion budgetsThermal distrotion budgets• Launch-system interfaces• Contamination control• Special thermal control requirements for components such as batteries, crystal oscillators and sensors• Interfaces with other subsystems such as:Interfaces with other subsystems, such as:
• Payloads• Propulsion• Attitude conrtol• Electrical powerElectrical power• Structures• Telemetry, tracking and command• Computer and data handling
142Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Thermal SubsystemThermal Subsystem
Thermal design development processThermal design development process
Input- S/C Configuration- Orbit data- Preliminary equipment temperature limits
Calculate:- TCS Wieight
- Preliminary equipment power profiles
Assume passive thermal design
TCS Wieight- TCS Power
Is TCS MP?YES
Establish:- Tompartment
I lt i i tYES
Calculate environmental heat loads on S/C
Calculate:T Are Ts
Is TCS MP?
- Insultaion requirements- Coatings
Establish:- Heater power
Heat ppe requirements
YES
NO
Assume modified passive TCS
- Tequipment
- Tompartment
Are Ts acceptable?
Is TCS MP?Is TCS SA?NO
- Heat ppe requirements
Establish:- Louver characteristics- Heat ppe requirements
YES
NO
Assume semi-active TCS
A ti TCS
Is TCS SA?Is TCS A?
NO
NO
Establish:- Radiator size- Transport loop characteristics
YES
NO
143Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Assume active TCS
Assume spacial TCS
Is TCS A?NO
YESEstablish special requirementsNO
P l iP l iPropulsionPropulsionSubsystemSubsystemSubsystemSubsystem
144Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Propulsion SubsystemPropulsion Subsystem
Basic definitionsBasic definitions• Propulsion system: system to provide thrust autonomously. It comprises every component
necessary for the fulfilment of the mission e g :necessary for the fulfilment of the mission, e.g.:
– Thrusters– Propellants
– Pressurisation subsystem– Tanks
– Valves– Filters– Pyrotechnic devices
– Electrical components such as power sources incase of electrical propulsion
– Sensors
• Propellant: material or materials that constitute a mass which, often modified from its originalstate, is ejected at high speed from a rocket engine to produce thrust.– In cold gas engines, the gas is accelerated due to the difference between storage and ambient
pressurepressure.– In chemical rocket engines, either a combustion reaction between two kind of propellants, fuel
and oxidiser, o a decomposition reaction of amonopropellant provides the energy to acceleratethemass.
– In electric engines, either an electromagnetic or an electrostatic field accelerates the mass,g gwhich in some cases has been heated to high temperatures or electric heating providesadditional energy to accelerate the mass (the latter in the case of power augmented thrustersand resistojets).
– Combinations of the above are possible.
145Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Propulsion SubsystemPropulsion Subsystem
Spacecraft pSpacecraft propulsionropulsion functionsfunctionsTask Descriptionp
Mission design (Translational velocity change)
Orbit changes Convert one orbit to another
Plane changes
Orbit trim Remove launch vehicle errors
Stationkeeping Maintain constellation position
Repositioning Change constellation position
A i d l ( l l h )Attitude control (Rotational velocity change)
Thrust vector control Remove error vectors
Attitude control Maintain an attitudeAttitude control Maintain an attitude
Attitude changes Change attitudes
Reaction wheel unloading Remove stored momentum
146Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Manoeuvring Repositioning the spacecraft axes
Propulsion SubsystemPropulsion Subsystem
Different types of space propulsion systemsDifferent types of space propulsion systems
Chemical rocketsLiquid
Cold gas
Monopropellant
Bipropellant
Dual mode
N
Solid
Hybrid
OPU
LSIO
ElectrothermalResistojets
Arcjets
PAC
E PR
O
Non-chemical rockets Electrostatic
j
Ion Thrusters
Hall Effect Thrusters
SP
Non-rocket propulsion
Electromagnetic Pulsed Plasma Thrusters
147Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
p p
Propulsion SubsystemPropulsion Subsystem
Main components of a Space Propulsion SubsystemMain components of a Space Propulsion Subsystem
Tank(s)Control
PropulsionPower
ElectronicsPowerUnit
Propellant Th ( ) ThrustPropellant
Di ib iPropellant Thruster(s) ThrustDistributionElements
148Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Propulsion SubsystemPropulsion Subsystem
Propulsion subsystem selection and sizing processPropulsion subsystem selection and sizing processfEstablishment of
propulsion system requirements
Definition of propulsion system options
Iterations with other subsystems
system options
Trade-off among the candidate propulsion
systems
Functions and tasks
Propulsive requirements
I l t ti i t Propulsion options propellantsImplementation requirements Propulsion options propellants
Propulsion system configuration
Propulsion system components
Preliminary system performance
SWOT analysis
Compliance matrix
Selection of the most suitable system
y y p
Mass budget
Propulsion system definition and design
Power budget
System size
Configuration
t
149Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
etc.
Propulsion SubsystemPropulsion Subsystem
Propulsion subsystem selection and sizing processPropulsion subsystem selection and sizing process1. List applicable spacecraft propulsion functions, e.g., orbit insertion, orbit
d l ll d d bmaintainance, attitude control, controlled de‐orbit...2. Determine V budget and thrust level constrains for orbit insertion and
maintenancel l f d l h l l f l h3. Determine total impulse for attitude control, thrust levels for control authority,
duty cycles (% on/off, total number of cycles) and mission life requirements4. Define propulsion system options:
C bi d t l i t f bit d ttit d t l• Combined or separate propulsion systems for orbit and attitude control• High vs. low thrust• Cold gas vs. liquid vs. solid vs. electric propulsion technology
5 Estimate key parameters for each option5. Estimate key parameters for each option• Effective Isp for orbit and attitude control• Thrust and MIB• Propellant mass• Propellant and pressurant volume• Configure the subsystem and create equipment list
6. Estimate total mass and power for each option
150Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
7. Establish baseline propulsion subsystem8. Document results and iterate as required
Propulsion SubsystemPropulsion Subsystem
General subsystem requirementsGeneral subsystem requirements• Thrust levels torque levels and linear impulse levels are required as a• Thrust levels, torque levels, and linear impulse levels are required as a
function of mission phase• Total impulse required by all maneuvers• Layout envelopes or constraints, centre of mass profile throughout the
mission• Allowable weight, mass properties, power and TT&C channel budgets as a
function of mission phase• Environments which will be imposed on the subsystem components• Reliability and redundancy requirementsy y q• Cost and schedule constraints• Subsystem safety – proof and burst to operating pressure
A ibili f li i h d l di ll l h i• Accessibility – for aligning thrusters and loading propellants at launch site• Cleanliness – both internal and external• Life
151Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Propulsion SubsystemPropulsion Subsystem
General subsystem interfacesGeneral subsystem interfaces• Propellant Tanks are located for s/c mass properties reasons, not RCS
convenience• Thrusters must be located to avoid or minimize plume impingement
effects (forces, thermal, contamination) on solar arrays, antennas andother appendages. Additionally they must be located so that neededthrusters are not covered by these appendages when stowed.
• Locate thrusters to point through s/c centre of mass or to have equalmoment arms, and to have alignment capability.
• Thermal interfaces are generally quite complicated, thrust chambersreach high temperatures (1500°C) and must be isolated from their valvesand s/c surfaces. Also since thrusters protrude through s/c exteriorsurfaces, they form heat leaks which must be insulated. Also, manypropellants have a more narrow acceptable temperature range than most/ h d d i i l tis/c hardware and require special precautions.
• The power subsystem may be called upon to provide high power andpulsed loads. Transient suppression is required to protect the s/c againstEMI hi h ld ff t it h t t d l i i it
152Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
EMI which could affect switch states and logic circuitry.
Propulsion SubsystemPropulsion SubsystemPropulsion subsystem interfaces with other subsystemsPropulsion subsystem interfaces with other subsystems
Structure
Inserts
GSE
Tanks filling
Tanks support estructure
Vibration levels
…
Testing
…
Thermal control
Radiation levels
DHS and TM/TC
Health monitoring
Conduction
Thruster and line thermal control
…
Failure detection
Valve drivers
…
AOCS
Thrust levels
Impulse levels
Power supply
Heaters
Sensors
153Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Impulse levels
Definition of firing modes
…
Sensors
Valves
…
Propulsion SubsystemPropulsion SubsystemPropulsion system design processPropulsion system design process
List aplicablespacacraft Functions
Orbit InsertionOrbit mainteneceAttitude Control
Determine TotalImpulse for Attitude
control.
Determine delta Vand Thrust level
constraints for orbitinsertion andMaintenace
Determine Thrustlevels for control
authority, duty cyclesand mission life
requirements
Determine propulsionsubsystem options
bi dDeterime level of
d d d
Estimate Key parameters foreach option
Eff i I d Th f Estimate total mass- combined or separate- Low or High thrust- Liquid, solid, electricor plasma
redundancy andoverall configuration
for each option
- Effective Isp and Thrust fororbit and attitude control- Propellant mass andPressurant Volume
Estimate total massand power for each
option
Qualify hardware atcomponent andsubsytem level
Finalize design andprocure/manufacture
equipment
Inetgrate intospacecraft system
level AssemblyIntegration and test
Are requirementsmet? Yes
No
subsytem levelequipment Integration and testProgram
NoNo
154Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Propulsion SubsystemPropulsion SubsystemPrincipal options for spacecraft propulsion systems (I/II)Principal options for spacecraft propulsion systems (I/II)
Propulsion Technology
Orbit Insertion Orbit Maintenance and Manoeuvering
Attitude Control
Typical Steady State Isp [s]Perigee ApogeePerigee Apogee
Cold Gas X X 30 – 70
S lid X X 8 Solid X X 280 – 300
Liquid
Monopropellant X X 220 –240
Biproprellant X X X X 305 –310
Hybrid X X X 250 – 340
Electric X X 300 ‐ 3000
155Taller de Diseño de Picosatélites (CUBESATS) y Estaciones de Tierra. J.M. del Cura
Propulsion SubsystemPropulsion Subsystem
Principal options for spacecraft propulsion systems (II/II)Principal options for spacecraft propulsion systems (II/II)Effective exhaust Thrust Maximum Delta v Propulsion methods in current use velocity
[km/s]
Thrust(N) Firing Duration Maximum Delta‐v
[km/s]
Solid rocket 1 ‐ 4 103 ‐ 107 minutes ~ 7
Hybrid rocket 1.5 ‐ 4.2 <0.1 ‐ 107 minutes > 3
Monopropellant rocket 1 ‐ 3 0.1 ‐ 100 milliseconds ‐minutes ~ 3
Bipropellant rocket 1 ‐ 4.7 0.1 ‐ 107 minutes ~ 9
D l d k t 7 i t Dual mode rocket 2.5 ‐ 5.3 0.1 ‐ 107 minutes ~ 9
Resitojet 2 ‐ 6 10‐2 ‐ 10 minutes
Arcjet 4 ‐ 16 10‐2 ‐ 10 minutes
Hall Effect Thruster (HET) 8 ‐ 50 10‐3 ‐ 10 months/years > 100
Electrostatic Ion Thruster 15 ‐ 80 10‐3 ‐ 10 months/years > 100
Field Emission Electric Propulsion (FEEP) 100 ‐ 130 10‐6 ‐ 10‐3 months/years(FEEP) 3 y
Pulsed Plasma Thruster (PPT) ~ 20 ~ 0.1 ~ 2,000 ‐ ~ 10,000 hours
Pulse Inductive Thruster (PIT) 50 20 months
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REFERENCESREFERENCES
1. Fortescue, “Spacecraft Systems Engineering”,2 Larson and Wertz “Space Mission Analysis and Design”2. Larson and Wertz, Space Mission Analysis and Design3. ECSS Standards4. Cubesat Standard5. Sarafin, “Spacecraft Structures and Mechanisms”6. Bruhn, “Analysis and Design of flight Vehicle Structures”7. Gilmore D.G, “Spacecraft Thermal Control Handbook Volume 1: Fundamental
Technologies8 P Sanz-Aranguez J S llorente J J Piñeiro “Vehículos espaciales II”8. P. Sanz Aranguez, J.S. llorente, J.J. Piñeiro, Vehículos espaciales II 9. Sutton and Biblarz, “Rocket Propulsion Elements”10.Brown, “Spacecraft Propulsion”11.http://ssdl.stanford.edu/cubesat12.http://www.cubesat.org (= http://www.cubesat.net)13.http://www.amsat.org14.http://www.ssel.montana.edu/merope15.http://ssdl.stanford.edu/cubesat15.http://ssdl.stanford.edu/cubesat16.http://www.cubesat.org (= http://www.cubesat.net)17.http://www.amsat.org18.http://www.ssel.montana.edu/merope
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