verde small satellite project uni stuttgart azores presentation v5_c

8/2/2019 VERDE Small Satellite Project Uni Stuttgart Azores Presentation v5_c

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Vegetation Research and Detection

Small Satellite Project 2011/2012

Elisabete Dias, Victor Hocke, Andreas Hornig, Nicolay Kbler, Mark Ltzner


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Agenda

1. Mission

2. Payload

3. Orbit

4. Subsystems

Structure / Thermal

Power System

Attitude Control System

Onboard Data Handling

Communications

5. System Budgets

University of

the Azores

University of

Stuttgart

10.02.12 Small Satellite Project 3


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Mission

Mission Definition



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Payload

Subcontractor

Berlin Space Technologies 6 spectral bands

near infrared, blue, yellow, green, red, red edge

GSD < 10 m (nadir)

Swath width100 km @ 600 km

MTF > 0.12

Favorable SNR

Mass < 20 kg

Power < 60 W(Target: 30 W)

Dimensions450 x 285 x 120 mm

Development time

18 - 24 month

Facts



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Payload

Continuous strip

SNR: 70 75

Permanent nadir orientation

Single scenes

Forward Motion Compensation (4:1)

Increased dwell time

SNR > 100

Requires detailed target planning

2 backup observation possibilities

Scan Mode Scene Mode

Operation Modes



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Orbit

Orbit Requirements

Full coverage of the Archipelago ofthe Azores

Constant lighting conditions

Max. 25 years

(space debris mitigationMin. 2 years (design lifetime)

Short revisit time

Low altitude

(for higher resolution)

1200 AZOT

Possible Orbits

Sun synchronous

Altitude / LTAN tbd

Lifetime and resolution limitaltitude to 500 600 km

Orbit Decay

10 40 km (solar activities)

Project

Mass AreaInitialaltitude

decay (2 years)

BIRD 94 kg 1,1 m2 565 km 27 km

SNOE 115 kg 0,9 m2 556 km 15 km

Orbit Design



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Orbit

Chosen swath width:95 km @ 575 km

Ground track distance:

93 km @ 575 km 2 km overlap

11:34 LTAN

7 consecutive observations,waiting time: 16 days

Orbit Design



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Structure / Thermal

Secondary Requirements

Low cost

Minimal + Simple Harness

Simple Integration

Simple servicing

Low mass

Stability of line of Sight (Camera stability)

Mandatory Requirements

Accesibillity of all Electronics

Eigenfrequency

Thermal Control

Quasistatic Loads must be withstood Dimensions must not exceed 600 mm x

700 mm x 850 mm (PSLV requirement)

Structure

Options

OptionsFEM check

Options

Trade off

Complete

FEM check

Detailed

construction

Structure



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Structure / Thermal

Barrel

Cube

Hexagon

Aluminium barrel Structure

Mass: ca. 110 kg

Hybrid Aluminum/Composite

Mass: ca. 110 kg

Hybrid Aluminum/Composite

Mass: ca. 100 kg

Options Trade-off



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Structure / Thermal

Weight Hexagon Cube Barrel

Mass 2 4 2 2

Cost 1 2 3 2

Stability ofline of sight

2 3 5 5

Thermalcontrol 1 2 5 5

Harness 1 5 2 2

Integration 1 5 2 2

28 26 25

Hexagon Cube Barrel

1. Lateral EF[Hz]

77 136 59.9

2. Vertical EF[Hz]

231 304 266

1. Lateral Mode

FEM Check

Options Trade-off



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Structure / Thermal

765mm

I-DEAS ModellCAD Modell

Complete FEMcheck

Structure

Lock System



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Structure / Thermal

Detailed FEM check

Lateral1. eigenfreq. [Hz] 77

2. eigenfreq. [Hz] 120



Vertical


Min eigenfreq. lateral: 45 Hz

Min eigenfreq. vertical: 90 Hz

1. Lateral Mode1. Longitudinal Mode



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Structure / Thermal

Max. Stress[N/mm] Max. Strain

X Direction 133 0,49*10-4

Y Direction 120 0,52*10-4

Z Direction 29.5 0,94*10-4

Aluminum Stress Composite Strain

Krit.

Krit.

Krit.

Max. Strain: 10-4

Max. Stress: 150 N/mm


Detailed FEM check


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2

1

3

4

5

6

7

8

9

3

1

22

21

1

Component Placement


Structure / Thermal


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Structure / Thermal

Cable support

Large Volume

for Harness

Detailed Construction



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Integration Procedure

Structure / Thermal

Step 1- AluminumStructure

Step 2- IntegrationPlatform

Step 4 - Solar PanelsStep 3- CompositeStructure

Simple Testing ofcomponents

Simple Integration

of Harness

Flight mode Integration of

Solar panels

Transport mode Integration of

Composite structure



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Structure / Thermal

Deployment Mechanism 6 x GFK brackets

Launch

Position

Deployed

Position

Detailed Construction



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Structure / Thermal

Orange: Primary heat conducting structure

Red: Radiators

Multilayer Insulation

Aluminum heat conducting plates are

fixed to the Composite by floating inserts

Line of Sight is highly incensitive to

thermal strain

High Power Electrical Components are

placed on the service plate(Battery/PCDU/OBC/COM Equip.)

Heater (critical components, e.g. Battery)

Thermal control:



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Structure / Thermal

Thermal Simulation

164 Thermal Knots

ComponentDissipated Energy

[W] (Hot Case)Dissipated Energy[W] (Cold Case)

OBC 10 10

MMU 15 5

RIU 5 5Batteries 5 5

PLC 10 -

PCDU 10 10TMTC 2 2

RW 7 7

Hot Case Radiator Area: 0.25 m2

Cold Case Heater Power: 15 W

Temperature Limits



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Structure / Thermal

Thermal Simulation: Maximum thermal loads (hot case)

Solar

Arrays

Battery

averaged Temp.

Payload



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Structure / Thermal

Thermal Simulation: Minimum thermal loads (cold case)

Solar

Arrays

Battery

averaged Temp.

Payload



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Electrical Power System

PCDU

Battery Cells

Load BalancerHeater

SolarPanels

B1 B2 B3 P2P1

System

SolarPanel

BatteryP

ack

EPS Overview



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0 10 20 30 40 50 60 70 80 90 100

0

50

100

150

200

250

300

350

400

Solar Power 5

P average 5

B1 B2 B3 P2P1Solar

Panel

Solar Panels

Solar power Failure Scenario


Orbitrun [%]Power[W]


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0 10 20 30 40 50 60 70 80 90 100

0

50

100

150

200

250

300

350

400

Solar Power 5

P average 5

0 10 20 30 40 50 60 70 80 90 100

0

50

100

150

200

250

300

350

400

Solar Power 5

Solar Power 4

P average 5

P average 4

Solar Input

System Power

Decrease in:

Design Power 120W

B1 B2 B3 P2P1Solar

Panel

Solar Panels





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0 10 20 30 40 50 60 70 80 90 100

0

50

100

150

200

250

300

350

400

Solar Power 5

P average 5

0 10 20 30 40 50 60 70 80 90 100

0

50

100

150

200

250

300

350

400

Solar Power 5

Solar Power 4

P average 5

P average 4

0 10 20 30 40 50 60 70 80 90 100

0

50

100

150

200

250

300

350

400

Solar Power 5

All Systems

Solar Power 4

P average 5P average 4

B1 B2 B3 P2P1Solar

Panel

Solar Panels

Above System Power

new system

power level





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0 10 20 30 40 50 60 70 80 90 100

0

20

40

60

80

100

120

140

160

180

Power Consumption during Worst Case Orbit

Power vs. Orbitrun

All Systems

All Systems avg

payload

com

acstherm

obdh

pow

orbitrun [%]

power[w

]


High DatarateCommunication

COM1

Observation

Heater

Standard DatarateCommunication

COM2 & COM3

High DatarateCommunication

COM1

Power Consumptionduring Worst Case Orbit



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+ Injection Mode

Standard Modes



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Solar Panel Trade off



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1st Layer

Optimized pattern with 80mm x 40mm (93%)

13 x 7 Cells per panel


300mm

8

00mm

Vs.

Solar panel (layer) design



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1st Layer



13 cells in series for nominal Voltage 28 V


Vs.




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1st Layer




2nd LayerSeries connection on panel


Vs.




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1st Layer




2nd LayerSeries connection on panel

3rd Layer

Parallel connection in panel sandwichFor capacity leverage to

Multiple interfaces to EPS system

Shunt System included


34

Vs.




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Battery trade-off



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Solar PanelArea usage = 0,93Efficiency = 0,3Degradation = 0,03 1/a

Battery

C/d cycles = 60000

DoD = 20 %Degradation = 0,05 1/a

ACS

Solar angle accuracy = 2,5CommandsCOM-turns (2x) = 45 a 15minForwardMC = 45 a 1min

Solar Environment

Solar Constant= 1370 W/m^2

System

e_daylight = 0,8e_eclipses = 0,85PowerConsumption = 95WTotal Power(20% margin) = 375W

Mission

Time = 2 aOrbit Period = 99 minDaylight = 64 %Eclipse = 36 %

Battery Specification

Energy:488 Wh

Capacity:23,2 Ah @ 21V

17,4 Ah @ 28V15,7 Ah @ 31V

System Power:160 WBoosting Level

Battery Design Criteria



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0 10 20 30 40 50 60 70 80 90 100

0

20

40

60

80

100

120

140

160

180

Orbit injection until full deployment

Power Consumtion vs. Full injection

All Systems

payload

com

acs

therm

obdh

pow

Solar System Power

orbit injection run [%]

power[w]

OrbitInjection

StepwiseActivation

Solar PanelDeployment

SystemCheck

InjectionFinished

StartingMission

CriticalPhase

Power ConsumptionDuring Injection Period



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Control

Navigation

S/C dynamics

Software (algorithms)

implemented on OBC

Actuator system

Reaction

Wheels

Magnetic

Torquer

Sensor system

Magneto-

meter

Star-

trackerIMU

Sun

Sensor

disturbances

control

commands torques

physicalstatesensor

measurem.

ground

commands

data

handling

Overview



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Definition:functional &

perfomance

requirements

Quantification:

disturbance

environment

System Design:architecture

componentselection &

sizing

Algorithm

Definition

Attitude estimation

(e.g. QUEST)

Controller design

(e.g. PID, H_infinity)

ACS Design Workflow



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The satellite has different ACS Modes:

1. Detumbling-Mode

2. Safe-Mode

3. Idle-Mode

4. Science-Modes:

4.1 Nadir-Pointing

4.2 Forward Motion Compensation

De-

tumbling

Safe-

Mode

Idle-

Mode

Science-

Modes

TC

TC

TC

FDIR

FDIRFDIR

AUTOTC

TC

AUTOTC TC

TC triggered by Telecommand

(Ground Station or Mission Time Line)

AUTO triggered by nom. condition

FDIR triggered by failure condition

Detumbling Safe Idle

Science

MGM x x x (x)

MGT x x x (x)STR x x

IMU x x

RW x x

SuS x x x x

ACS Modes



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Counter-rotation enlarges integration time

Rotation for FMC = 4

4x observation time constant pitch rate approx. 0.5/s

total rotation angle approx. 30

observation time approx. 1 Minute

Forward Motion Compensation



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2 Star Trackers

ST-100 (Berlin Space Technologies)

Accuracy: 200/30Star map included

2 Magnetometer (ZARM)

2 Inertial Measurement Units

Sensonor STIM210

MEMS-based 3-axis gyro module0.5/h bias instability, 0.10/h ARW

8 Sun Sensors (IRS)

Criteria Weight

SensonorSTIM210

LitefmuFORS-2

Cost 20% 3 2

ARW 25% 2 3

Bias 25% 3 2

Power 10% 3 2

Volume 10% 3 2

Mass 10% 3 2

Total 2,75 2,25

Sensor Concept



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3 Magnetic Torquers (ZARM)

two coils per unitLinear Dipole Moment 6 Am2

4 Reaction Wheels

(Astro- und Feinwerktechnik)

angular momentum: 0.1 Nms @ 5000 rpm

nominal torque: 0.005 Nm

tetrahedral configuration (redundancy)

Actuator Concept



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constrains:

shadowing effects (SuS, STR)

sun/earth blinding (STR)electromagnetic compatibility (MGM, MGT)

alignment

1. Reaction Wheels (RW)2. Sun Sensor (SuS)

3. Inertial Measurement Unit (IMU)

4. Star Tracker (STR)

5. Magnetometer (MGM)

6. Magnetic Torquer (MGT)

1

2

4 5

6

3

ACS Component Placement



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Tasks

Collect and process housekeeping data

Command attitude and thermal Control System

Store and process telecommands (CCSDS)

Send Data and Telemetry

ACS Attitude Control System

MMFU Mass Memory and Formatting Unit

OBC Onboard Computer

PCDU Power Control and Distribution Unit

PLC Payload ComputerRIU Remote I/O Unit

TCS Thermal Control System

TM/TC Telemetry/Telecommand

OBDH Configuration



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Supplier: Aeroflex Gaisler

RTEMS

Flight Heritage

MIL-Std 1553

Spacewire

89 DMIPS

Base Clock frequency 66 MHz

Supplier: SSTL

RTEMS

Flight Heritage

MIL-Std 1553

Spacewire

1800 DMIPS

Base Clock frequency 250 MHz

LEON3 UT699 IBM Power PC750 FL


Onboard Computer Trade-off

Not Rad hardenedCheaper Purchase and Testing

Rad hardenedexpensive purchase and testing



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Operating

System:RTEMS or others

Internal Memory:

265 MiBytes

2 MiBytes MRAM

16 MiBytes Flash

IBM PPC750FL

OBC Performance

COTS Flash Memory

Management Unit High Quality Product

Mass Memory and Formatting Unit

(+ Housekeeping

Data)



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Communication

COM3

COM2COM1

COM1 S-BAND TX High Data Mode, Payload Data

COM2 S-BAND TXRX of Telemetryand TX of Payload Data

COM3 L-BAND TXRX of Basic Telemetry

Tracking

Wakeup for Injection Phase

Power Mode Change

Communication System



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Communication

Horn

AntennaS-Band

COM1

OMT

CircularPolarization

D/AConverter

Modulator FrequencyMixer

Antenna13cm BandC

OM2

D/AConverter

Modulator FrequencyMixer

A/DConverter

De-Modulator

FrequencyMixer

Antenna23cm BandC

OM3

D/A

ConverterModulator

Frequency

Mixer

A/DConverter

De-Modulator

FrequencyMixer

Components



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Communication

IRS in-house manufactured

testing, validation and calibration campaigns (ex/internal)

hybrid COTS and space hardend components

Antenna Trade-off



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Communication

path link 0 and 90 elevation (2767 km / 575 km) output power drop from 1 W to 0,75 W

small changes atmospheric losses

Main Worst Case properties:

Link Budget (1)



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Communication

(ctd. 2nd Payload Constellation)

Link Budget (2)



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Communication

230mm60mm

Corrugated Horn

Circularly Polarization

Output Frequency2,4497 GHz

Antenna analysis (with TICRA Champ)


C i i


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Communication

IRS Groundstation

2,5 m parabolic antenna

S-Band (2,45GHz)

Gain 33 dB

Antenna analysis (with TICRA Grasp)


C i ti


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Communication

SolarBank Angle = local time

SystemPower max = 40 WMMU = 200 GB

ACSPointing Accuracy = 2Attitude = 2

FrequenciesAmateur Radio Bands23cm, 13cm

PayloadMission Data = 30000 MBCompression(lossless) = 10%

MissionGroundstations = 2Visibility = 15minRevisit Time = 21 dMission Time = 7 d

COM SpecificationCOM1

2,44 GHz1200 kbit/s8FSK

EnvironmentPathlength best = 575 kmPathlength worst = 2770km

COM22,41 GHz2,43 GHz100 kbit/sQPSK8FSK

COM3

1,263 Ghz1,264 GHz10 kbit/sQPSK8FSK

Constellation1,2646 kbit/sQPSK

Design Criteria


C i ti


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Communication

Global Volunteer Sensor Grid

Connected via the Internet

Amateur Radio Bands

Amateur Radio Operators and ordinary people

Global Sensor Grid

Tracking Data-Dump-Mode

Citizen Science & Crowd Communication


Constellation Distributed Ground Stations

Communication


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Communication

CONTRA PRO

Global distribution of stations

Overall more contact time results to5% of COM1 datarate (1Mbit/s)

Cost efficient usage of frequency

No licencing of frequency band

No licences for operator

keeping amateur radio community happy

External tracking for orbit determination

Simple beacon and protocol design

Reduced communication

contact times per station

Only 6 kbit/s

Using amateur frequency

bands with smaller

bandwidth


Constellation Distributed Ground Stations

System Budgets


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System Budgets

Mass Budget


System Budgets


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System Budgets

VERDE Budget

Budget Relations in Respect to Hardware, Logistics & Working Hours

Satellite

Logistcs

Working Hours

VERDE Budget

Budget Relations in Respect to Components

Payload

COM

EPS

OBDH

ACS

STRUCTUR

THERMAL

Testing

Rest

Transport

Business Costs

Working Hours

Financial Budget


Thank you!


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Thank you!

Thanks to all tutors at the Azores and in Stuttgart!

Questions?


Contact


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Contact

VERDE Team

PayLoad: Elisabete DIAS

ACS & Orbit: Victor HOCKE COM & EPS & Constellation: Andreas HORNIG

OBDH & Thermal: Nicolay KBLER

Structure & Analysis: Mark LTZNER

Universities

University of Stuttgart www.uni-stuttgart.de Institute for Space Systems (IRS) www.irs.uni-stuttgart.de

Small Satellite Project www.kleinsatelliten.de

University of the Azores www.uac.pt


Email:[email protected]

Facebook:http://on.fb.me/smallsatellitesazores

Sources


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Sources

Companies

Berlin Space Technology www.berlin-space-tech.com

Azurspace www.azurspace.com

Emcore www.emcore.com

Saft Batteries www.saftbatteries.com

Point of Contact David REULIER

A123 Systems www.a123systems.com ZARM Technik www.zarm-technik.de

Sensonor www.sensonor.com

Astra- und Feinwerktechnik www.astrofein.com

Aeroflex Gaisler www.gaisler.com

Surrey Satellite Technology Limited www.sstl.co.uk


(in order of appearance)

Sources


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Sources

Projects

Constellation www.aerospaceresearch.net/constellation

Distributed Ground Station Network www.hgg.aero Point of Contact Andreas HORNIG [email protected]

Software

AGI Satellite Tool Kit (STK) www.agi.com

I-DEAS www.plm.automation.siemens.com/de_de

ESATAN-TMS www.esatan-tms.com

TICRA Grasp & Champ www.ticra.com


verde small satellite project uni stuttgart azores presentation v5_c

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