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© Copyright QinetiQ Limited 2012 QinetiQ Proprietary
Julien Tallineau
A presentation to: ULg
12/12/2012
1
Satellite Engineering PROBA Familly
QinetiQ Space nv © Copyright QinetiQ Limited 2010
0 TABLE OF CONTENT
1. Introduction
2. PROBA Approach
3. PROBA Satellites
4. PROBA Case Study
5. Conclusions
2
QinetiQ Space nv © Copyright QinetiQ Limited 2010
1 INTRODUCTION
Satellite Engineering
1. Customer Need (Scientist)
2. Creation of System Requirements
3. Phase 0 (CDF Study)
4. Phase A (Feasibility Study)
5. Phase B (Preliminary Design)
6. Phase C (Final Design)
7. Phase D (Manufacturing / Testing)
8. Phase E (Launch / Commissionning/Operations)
9. Phase F (De-orbiting)
7
QinetiQ Space nv © Copyright QinetiQ Limited 2010
1 INTRODUCTION
Satellite Engineering
1. Customer Need (Scientist)
2. Creation of System Requirements
3. Phase 0 (CDF Study)
4. Phase A (Feasibility Study)
8
QinetiQ Space nv © Copyright QinetiQ Limited 2010
1 INTRODUCTION
Satellite Engineering
5. Phase B (Preliminary Design)
• Detailed System Analysis
• Preliminary Subsystem Analysis
• Trade-offs
6. Phase C (Final Design)
• Detailed Subsystem Analysis
• Procurement
• Qualification testing
9
QinetiQ Space nv © Copyright QinetiQ Limited 2010
1 INTRODUCTION
Satellite Engineering
7. Phase D
• Manufacturing
• Acceptance Testing
• Requirement Verification
• Shipment to Launch site
10
QinetiQ Space nv © Copyright QinetiQ Limited 2010
1 INTRODUCTION
Satellite Engineering
8. Phase E
• Launch
• Commissionning
• Operations
9. Phase F (De-orbiting/End of Life)
• None in this case
11
QinetiQ Space nv © Copyright QinetiQ Limited 2010
13
2 PROBA APPROACH
PROBA Philosophy
• PRoject for On-Board
Autonomy (PROBA)
• Missions
− In Orbit Demonstration
− Earth Observation
• Developed under ESA TEC
department
PROBA-1
PROBA-2
PROBA-V
PROBA-ALTIUS
QinetiQ Space nv © Copyright QinetiQ Limited 2010
2 PROBA APPROACH
14
LightSat Approach
• In-Orbit Demonstration (IOD) aiming at
- Demonstrating new techniques that could lead to new space system
- Reduced cost
• Drastic reduction of the number of requirements
• Keep the system as simple as possible with only limited inter-dependencies
• Results rather than paper oriented reviews
• Accept higher level of risk
QinetiQ Space nv © Copyright QinetiQ Limited 2010
2 PROBA APPROACH
Satellite Engineering Tools
1. Requirement Management Tool (DOORS)
2. Mission Analysis Tool (MATLAB)
• Orbit propagator (J2, Drag, Third Body, SRP)
• Attitude Control (Magnetic, Nadir, Sun, Target)
• Incoming fluxes
• Ground Stations Visibility
• In orbit Maintainance (To be developed)
• In orbit Manoeuvering (To be developed)
• Formation Flying/Rendez vous (To be developed)
15
QinetiQ Space nv © Copyright QinetiQ Limited 2010
2 PROBA APPROACH
Satellite Engineering Tools
1. Thermal Analysis Tool (ESATAN-TMS)
2. Configuration Tool (IRON-CAD/PRO-E)
• IRON-CAD allows for fast iteration
• PRO-E is similar to CATIA
3. Structural Analysis Tool (NASTRAN)
16
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3 PROBA SATELLITES
• PROBA – 1
• PROBA – 2
• PROBA – V
17
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3 PROBA - 1
Mission
1. In-orbit demonstration and evaluation of new hardware/software spacecraft
technologies and onboard operational autonomy
2. Obrital Parameter
3. Injection Parameter
19
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3 PROBA - 1
Mission
1. RAAN selected for 10:00 Local Time Descending Node.
20
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 1
Mission
1. Launcher is PSLV
• Nominal separation rate of 2° per sec.
• Worst Case separation rate of 8° per sec.
• Inclination accuracy of 0.2°
• Altitude accuracy of 35km
2. Radiations of 9 krad for 3 years mission
• Solar maximum is considered
• 3.5mm of Aluminium considered
21
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 1
Mission
1. Ground segment visibility (REDU)
• 30% of all orbits have contact with the ground station (duration > 0 minutes)
• 21.23 more than 6 minutes
• 10.88% more than 8 minutes
• The longest time between two passes
over the ground station is 11hr 44 min
22
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3 PROBA - 1
Mission
1. Scenario
• Launch and Early Operation Phase (LEOP)
− Boot after separation
− De-tumbling
− First Ground Contact + AOCS/GPS switched ON
• Commissioning (two months)
− Low Autonomy
• Nominal Operations
− High Autonomy
23
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 1
Satellite Design - Configuration
1. Single H Structure
2. High Unit Density
3. Body Mounted Solar Panel
4. Cut out in panels:
• Star-Trackers
• Instruments
24
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3 PROBA - 1
Satellite Design - Structure
1. Honeycomb panels
• Aluminium core
• Aluminium edge
• Alumiunium facesheet (Primary structure)
• CFRP facesheet (Secondary structure)
25
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 1
Satellite Design - Mechanics
1. Spacecraft Mass = 95 kg
2. Balance Mass of 2.5kg for
CoG Location Requirement
26
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3 PROBA - 1
Satellite Design - Power
1. Power budget approach could be:
• Rely on Solar Array (SA) in Sun and on Battery in Eclipse
• Rely on both Battery and SA when available.
2. Power budget is positive, independently of the scenario.
27
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3 PROBA - 1
Satellite Design – RF COM
1. Downlink (S-Band)
• Flux margin of 7dB (@max rate = 1Mbps)
• Flux margin of - 2dB (@min rate = 250kbps)
• Telemetry Recovery margin of 8dB
2. Uplink (S-Band)
• Carrier Recovery margin of 26dB
• Telecommand Recovery margin of 17dB
28
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3 PROBA - 1
Satellite Design – Thermal
1. Passive thermal control
• Thermal Blankets + MLI
• Black paint (internal panel+electronic box)
29
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3 PROBA - 1
Satellite Design – Data & memory
1. One Image sequence can be stored before next downlink
• Mass Memory size = 1Gbit
• Image sequence size = 5 image x 19 spectral lines x 742 spatial lines x 9 kbit/line
= 665 Mbit.
2. Data downlinked = 1140Mbit every 12 hours
• Max data rate
• Time ≈ 1300sec (Total Ground Visibility)
30
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3 PROBA - 1
23 000 km
27 000 km
25 000 km
23 000 km23 000 km
27 000 km27 000 km
25 000 km25 000 km
Position determination
GPS RX
Position determination
Magnetometer (2)
Measure continuously the
Earth Magnetic field and
determine itselve where the North is.
N
Z
N
Z
N
Z
•Takes pictures of stars
• Compare it with its internat catalog.
• Compute the satellite orientation/position
Orientation/Position
Star-Tracker (3)
Orientation/Manoeuvre
Magnetotorquer (4)
N
Z
.
N
Z
N
ZZ
.
N
Z
N
Z
• Magnetic Coil
• Align itself to Magnetic lines
Orientation/Manoeuvre
Rection Wheel (4)
Accelerates or decelerates while momentum conservation implies the PROBA to rotate the other way.
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 1
Satellite Design – AOCS
1. Guidance
= determination of the desired path of
travel from the satellite's current
location to a designated target
2. Navigation
= determination of the satellite’s
location, velocity and attitude
3. Control
= manipulation of the forces needed to
track guidance commands while
maintaining satellite stability
32
AOCS Software - Navigation - Guidance - Control
Reaction Wheels (4)
Magneto- meters (2)
Magneto- torquers (4)
GPS Receiver
Star Tracker (2)
Head
Head
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3 PROBA - 1
Satellite Design – AOCS ( Pointing Modes)
33
• Inertial pointing
• Sun Pointing
• Motion compensation
• Multiple scans • On-track
• Off-track
• On-track
• Off-track
Utilisation:
• Astronomy
• Solar Physics
Utilisation:
• Earth Observation
• Telecommunications
• Space Weather
Utilisation:
• High Resolution
Imaging
• Elevation Modeling
• Disaster Monitoring
Inertial Pointing Earth Pointing Point and Stare Scanning Modes
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 1
Satellite Design – AOCS
1. Specifications
2. AOCS SW Modes
• Quiscient
• Magnetic
• Celestial
• Terrestrial
34
Errors at 95% confidence level
Absolute Pointing Error (APE) 100 arcsec
Relative Pointing Error (RPE) 5 arcsec over 10 s
Absolute Measurement Error (AME) 10 arcsec
Quiscient Mode
- No AOCS
- Most units are OFF
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 1
Satellite Design – AOCS
1. Specifications
2. AOCS SW Modes
• Quiscient
• Magnetic
• Celestial
• Terrestrial
35
Errors at 95% confidence level
Absolute Pointing Error (APE) 100 arcsec
Relative Pointing Error (RPE) 5 arcsec over 10 s
Absolute Measurement Error (AME) 10 arcsec
Magnetic Mode
- Sensor: magnetometer
- Actuator: magnetotorquers + 1 RW stby (momentum bias)
- Guidance: No
- Navigation: No
- Control: Bdot Algorithms (Kinetic Energy Dumping)
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 1
Satellite Design – AOCS
1. Specifications
2. AOCS SW Modes
• Quiscient
• Magnetic
• Celestial
• Terrestrial
36
Errors at 95% confidence level
Absolute Pointing Error (APE) 100 arcsec
Relative Pointing Error (RPE) 5 arcsec over 10 s
Absolute Measurement Error (AME) 10 arcsec
Celestial Mode
- Sensor: Star-tracker + Magnetic mode sensors
- Actuator: Reaction Wheels + Magnetic mode actuatord
- Guidance: Sun pointing, Inertial pointing
- Navigation: Attitude and Orbit evaluator (Kalman Filter)
- Control: State feedback, PID, angular momentum control
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 1
Satellite Design – AOCS
1. Specifications
2. AOCS SW Modes
• Quiscient
• Magnetic
• Celestial
• Terrestrial
37
Errors at 95% confidence level
Absolute Pointing Error (APE) 100 arcsec
Relative Pointing Error (RPE) 5 arcsec over 10 s
Absolute Measurement Error (AME) 10 arcsec
Terrestrial Mode
- Sensor: GPS + celestial mode sensors
- Actuator: celestial mode actuators
- Guidance: Nadir, Fixed-target pointing, Imaging scans
- Navigation: Same as Celestial mode
- Control: Same as Celestial mode
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 1
Launched on the 22/10/2001 from India
38
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 1
LEOP Activities
1. Rotating Energy is dissipitated progressively using the magneto-torquers.
39
0,0E+00
2,0E-03
4,0E-03
6,0E-03
8,0E-03
1,0E-02
1,2E-02
1,4E-02
0,00 1,00 2,00 3,00 4,00 5,00 6,00
Sq
ua
re a
ng
ula
r ra
te (
rad
/se
c)
2
Five hours
to detumble!
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 1
Normal Operations Activities
40
Ile de Ré,
France
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 1
Normal Operations Activities
41
Etna eruption,
Sicily, 20.10.2002
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3 PROBA - 1
Normal Operations Activities
42
North Sentinel Island
India, 29.05.06
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3 PROBA - 1
Normal Operations Activities
43
Palm Island
Dubai
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3 PROBA - 2
Mission
1. In orbit Demonstration, PROBA-2 aimed at technological innovation.
Altogether, 17 new technological developments and four scientific
experiments are being flown on Proba-2.
2. Orbital Parameter
• RAAN selected for
6:00 AM Local Time
Ascending Node
45
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3 PROBA - 2
Mission
1. RAAN selected for 6:00 AM Local Time Ascending Node
46
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 2
Mission
1. Launcher is Rockot
• Worst Case separation rate of 8° per sec.
• Inclination accuracy of 0.05°
• Altitude accuracy of 12km
• RAAN accuracy of 3.75° (≈15min LT)
2. Injected via the Breeze upper stage
47
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3 PROBA - 2
Mission
1. Ground segment visibility
• REDU
• KIROUNA
49
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3 PROBA - 2
Mission
1. Scenario
• LEOP
• Commissioning (three months)
• Nominal Operations
2. Spacecraft Modes
• Separation
• Safe
• Observation
• Stand-by
50
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 2
Satellite Design - Configuration
1. Single H Structure
2. Sun Shield
• Standard STR
• Bepi-Colombo STR
3. High Unit Density
4. Deployable Solar Panel (x2)
52
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 1
Satellite Design - Mechanics
1. Spacecraft Mass = 122.5 kg
2. CoG Choice
• Folded Configuration (LV requirement)
• Deployed Configuration (GNC requirement)
53
NB: LV I/F Ring Mass included
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 2
Satellite Design - Power
1. Power budget is positive, independently of the mode
• Observation (w/o TX
• Observation with TX
• Safe mode with TX (worst Beta-angle).
54
Definition
Beta Angle = angle between the Sun-Earth vector and the orbital plane.
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 2
Satellite Design – Power
1. Battery DoD (Ah)
in function of time
2. Non Regulated bus 28V
57
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 2
Satellite Design - Power
1. Power budget while de-tumbling !
2. Trade-off between:
• Performance (GNC)
• Time (LEOP schedule)
• Battery Discharge (Higher DoD)
58
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 2
Satellite Design – Thermal
1. Passive thermal control
• Thermal Blankets + MLI + Chotherm
• Black paint (internal panel+electronic box)
60
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 2
Satellite Design – Data & Processing
1. Processing budget shows how busy is the processor with all the units +
instruments.
• On Software Verification Facility
• On S/C during System Validation Test 5
61
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3 PROBA - 2
Satellite Design – AOCS
1. Low power resistojet (Xenon)
• 15W for heater (x2)
• 50s Isp (min)
• 20mN Thrust
• Total ∆V = 2m/s
62
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 2
Satellite Design – AOCS
1. Sensors
• 2 Star-tracker
• 2 GPS RX
• 2 Magnetor-Meter
2. Actuators
• 4 Reaction Wheels
• 3 dual-coil magneto-Torquer
63
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4 CASE STUDY: PROBA-3
• The Mission
• Phase A
• Phase B
64
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3 PROBA - 3
Mission
1. The PROBA-3 mission will provide an opportunity to validate and develop
• The Metrology and Actuation techniques / technologies
• The Guidance strategies and Navigation and Control algorithms necessary for
formation flying.
2. One mission, two spacecrafts:
• Coronagraph S/C (CSC)
• Occulter SC (OSC)
65
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3 PROBA - 3
Mission
1. High Elliptical Orbit (HEO) with 20 hours period
• Low perturbation in Apogee
• Low AoP drift (fixed above REDU)
• Limited Eclipse duration
• Radition Issue
• Stringent Constraint on RF Link
• Delta-V issue.
66
Parameter Value
Orbit type HEO
Perigee altitude 600km
Apogee altitude 60530km
Inclination 59°
Eccentricity 0.8062
AoP 188°
RAAN 173°
Epoch Jan 2017
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 3
Possible Launchers
1. PSLV Launcher
• Low Cost
• Heritage from PROBA-1
• Reduced Volume
2. Falcon 9 Launcher
• High Cost
• Higher Performance
• Large Volume
• No Heritage
67
PSLV
Falcon 9
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3 PROBA - 3
Which one of the two shall you design your Spacecraft for ?
68
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3 PROBA - 3
Which one of the two shall you design your Spacecraft for ?
ANSWER = The Two !
But it is up to ESA + Delegates to decide the mission budget
69
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3 PROBA - 3
What would you put in your spacecraft ?
70
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3 PROBA - 3
What would you put in your spacecraft ?
71
Subsystem Design
Structure Aluminium/CFRP/Invar/Titanium ?
Thermal Passive/Active ?
Mechanism Body Mounted/Deployable SA?
Power Large/Small SA ?
Large/Small Battery?
GNC Sensor?
Actuator?
RF High/Low Gain COM Antenna?
High/Low Gain FF Antenna?
Payload What do you need to perform the mission?
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA – 3 Phase A
Outcome of Phase A is our STARTING POINT
1. Configuration
2. Mass
3. Power
4. Avionics
5. Thermal
6. Propulsion
7. Link & Data
8. Payload
73
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3 PROBA – 3 Phase A
Coronagraph Satellite Overview
1. Twelve subsystems
2. Five entities
74
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3 PROBA – 3 Phase A
Coronagraph Satellite Overview
1. From Top
2. From Bottom
75
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3 PROBA – 3 Phase A
Coronagraph Satellite Overview
1. From Back Left
2. From Back Right
76
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3 PROBA – 3 Phase A
Coronagraph Satellite Overview
1. From Front
2. From Inside
77
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3 PROBA – 3 Phase A
Coronagraph Satellite Overview
1. Mass Budget
• “Total CSC dry mass including I/F ring with L/V shall be less than 360kg (with
margins)”.
• Current estimate: 376.44kg
2. Power Budget
• “ Total CSC maximum power consumption shall be less than 294W (with margins)”
• Current estimate: 353.15W
78
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3 PROBA – 3 Phase A
Coronagraph Satellite Overview
1. Avionics
• Centrilized around Advance Data & Power Management System (ADPMS)
• Support of Interface Electronics
See block diagram
79
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3 PROBA – 3 Phase A
Coronagraph Satellite Overview
1. Thermal
• Solar array temperature range (-169°C to +79°C).
• Battery operational temperature range:
− -10°C minimum operational temperature
− +40°C maximum operational temperature
• Star Tracker detector maximum operational temperature
− Current prediction: 40°C
− Required: 15°C
80
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3 PROBA – 3 Phase A
Coronagraph Satellite Overview
1. Propulsion System (HPGP)
• 2x4 thrusters to raise orbit
• Constrains
− Pre-warming needs 64W (=2x4x8W) during 30 min
− Propellant needs to be kept
above 10°C (Always)
• Performance
− Isp = 202 EoL
− Thrust = 1N
81
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3 PROBA – 3 Phase A
Coronagraph Satellite Overview
1. Propulsion System (Cold Gas)
• Siwteen thruster for GNC and FF
• Performance
82
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3 PROBA – 3 Phase A
Coronagraph Satellite Overview
1. GNC Sensors
• 6 Sun Acquisition Sensors
• 2x3 Gyros
• 2x3 Acceleromter
• 3 Star Trackers Head + 2x1 Electronics
• 2x1 GPS
2. GNC Actuators
• 3+1 Reaction Wheels
• Cold Gas thrusters
83
3. GNC FF
• Omni-directional RF
Sensor (FFRF)
• Coarse Lateral Sensor
• Fine Formation Sensor
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3 PROBA – 3 Phase A
Coronagraph Satellite Overview
1. Link Budget
• “The CSC shall be able to downlink data at a symbol rates of 256ksps and 2Msps
using REDU-3 Ground Station”
• “The CSC shall be able to receive TC data at a symbol rates of 64ksps
using REDU-3 Ground Station”
• Current estimation:
− Downlink not closed for 2Msps (@apogee)
− Uplink not closed for 64ksps (@apogee)
84
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3 PROBA – 3 Phase A
Coronagraph Satellite Overview
1. Data Budget
• “The CSC shall be able to downlink 8.5Gbit of data per day”
• Current estimate
− Min rate (256ksps)
− Max rate (2Msps)
85
0,00%
10,00%
20,00%
30,00%
40,00%
50,00%
60,00%
70,00%
80,00%
90,00%
100,00%
0 10 20 30 40 50 60 70 80D
aily C
overa
ge P
erc
enta
ge
COR Altitude (1000 km)
Coverage Percentage Needed for Downlink of CORONAGRAPH data (8.5GBit/Daily)
Redu Coverage
Redu+Santiago+Perth Coverage
Needed Coverage Percentage Low Rate DL (8.5GBit Data/24h)
Needed Coverage Percentage High Rate DL (8.5GBit Data/24h)
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3 PROBA – 3 Phase A
SUMMARY
1. Satellite is too heavy
2. Satellite is too power consuming
3. Satellite is too hot or too cold
4. Satellite is too far to close its downlink and uplink
5. Satellite is too far to downlink its science data
6. Satellite is too un-protected wrt radiations (20krad under 2mm Al)
86
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3 PROBA – 3 Phase A
ANSWER
1. Mass & Power reduction exercise
2. Perform a detailed thermal analysis
• Active control
• Electronics Location
• Radiator size
3. Review Operation concept for U/D link
4. Increase Satellite Shielding
88
+ MINIMIZE THE COST !
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3 PROBA – 3 Phase B
Mass reduction
1. Who are the biggest contributors ?
• Structure
• Formation Flying
• Propulsion System
• Payload
90
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3 PROBA – 3 Phase B
Mass reduction
1. Structure
• Shield the spacecraft with outer panels !
• Remove materials in the Bottom Board !
• Remove two panels while re-arranging structure
• Shorten the satellite
• Consider LV I/F ring as part of system mass margin
2. GNC & Propulsion
• Remove the Accelerometer
• Remove Cold Gas Propulsion System (Transfer to OSC)
• Include 2x4 additional HPGP thruster for 6DoF
92
3. Payload
• Replace the FFRF
• Shorten Payload
4. Other
• Direct Injection !
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3 PROBA – 3 Phase B
Mass reduction results
1. Structure has been reinforced (corner bracket)
• Honeycomb Al-Al-Al (Primary & Secondary Structure )
• Honeycomb CFRP-Al-CFRP (Solar Cells accommodation)
2. Satellite has better shielding
3. Mass has decreased to 318kg
See Mass Budget
93
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3 PROBA – 3 Phase B
Power reduction
1. Who are the biggest contributors ?
• Thermal control = 91W (due to propellant thermal constraint)
• Propulsion (HPGP) = 128W (16x8W after the mass reduction)
• Payload = 40W (pre-warming)
• Reaction Wheel = 42W (when 3 accelerating + 1 constant speed)
2. Still to be included within the 294W
• STR / Gyro / GPS / RF systems / On-Board Computer / Propulsion Electronics / …
94
30%
43%
13%
13%
99%
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA – 3 Phase B
Power reduction
1. Who are the biggest contributors ?
• Thermal control = 91W (due to propellant thermal constraint)
• Propulsion (HPGP) = 128W (16x8W after the mass reduction)
• Payload = 40W (pre-warming)
• Reaction Wheel = 42W (when 3 accelerating + 1 constant speed)
2. Still to be included within the 294W
• STR / Gyro / GPS / RF systems / On-Board Computer / Propulsion Electronics / …
95
30%
43%
13%
13%
99%
What would do a good system engineer ?
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA – 3 Phase B
Power reduction
1. Thermal Control
• Satellite wrapped into MLI
• Electronics as close as possible to cold points
2. Propulsion
• Only half of thruster pre-warmed + duty cycle
• Only less than half the power is given at the same time (longer pre-warming!)
3. Payload
• Longer pre-warming
4. GNC
• FFRF removed
96
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3 PROBA – 3 Phase B
Power reduction
1. Thermal Control reduced to 75W (instead of 91W)
2. Propulsion reduced to 33,6W (instead of 128W)
3. Payload reduced to 10W (instead of 40W)
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3 PROBA – 3 Phase B
Power reduction
1. Thermal Control reduced to 75W (instead of 91W)
2. Propulsion reduced to 33,6W (instead of 128W)
3. Payload reduced to 10W (instead of 40W)
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What is the next
step ?
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA – 3 Phase B
Electrical Architecture
1. Power Generation & Storage
• Solar Array
• Battery
2. Power Conditioning
Distribution Unit
• ADPMS
3. Connections
• Safe & Arm
• Umbilical Connection
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3 PROBA – 3 Phase B
Solar Array Design
1. Main components
• Cells Series (TBD)
• String Parallel (TBD)
• 6xSection (TBD strings)
2. Secondary components
• Shunt Selection
• Dump Resistor
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3 PROBA – 3 Phase B
Solar Array Design
1. Main components
• Cells Series (TBD)
• String Parallel (TBD)
• 6xSection (TBD strings)
2. Secondary components
• Shunt Selection
• Dump Resistor
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How can we
calculate this?
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA – 3 Phase B
Solar Array Design (3G28%)
1. Evaluate the degradation?
• Coverglass thickness
• Degradation of Electrical Parameters
• Degradation of Temp. Coefficient
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3 PROBA – 3 Phase B
Solar Array Design (3G28%)
1. Evaluate the degradation?
• Coverglass thickness
• Degradation of Electrical Parameters
• Degradation of Temp. Coefficient
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3 PROBA – 3 Phase B
Solar Array Design
2. Evaluate the number of cells ?
• Max battery voltage to be provided (29.4V)
• Compute all voltage drop
• Compute number of cells (MPP)
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18 Cells / Strings
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3 PROBA – 3 Phase B
Solar Array Design
3. Evaluate the number of strings ?
• Max current allowed by ADPMS (12A)
• Compute string current
− EoL ( di/dt < 0)
− Minimum Solar Cste
(di/dC > 0)
− Operating temperature
(di/dT>0 but dU/dT<<0)
− Operating point
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3 PROBA – 3 Phase B
Solar Array Design
3. Evaluate the number of strings ?
• Max current allowed by ADPMS (12A)
• Compute string current
− EoL ( di/dt < 0)
− Minimum Solar Cste
(di/dC > 0)
− Operating temperature
(di/dT>0 but dU/dT<<0)
− Operating point
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23 (+1) Strings
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3 PROBA – 3 Phase B
Solar Array Design
4. Evaluate the Power available?
• Power = Current * Voltage
• 1 String Failure Tolerance
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3 PROBA – 3 Phase B
Solar Array Design
4. Evaluate the Power available?
• Power = Current * Voltage
• 1 String Failure Tolerance
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3 PROBA - 3
What if GNC has a failure?
ANSWER = Need to be taken into account if pointing accuracy of SUN
POINTING is decreased!
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3 PROBA – 3 Phase B
Battery Design
1. Main components
• Cells Series (TBD)
• String Parallel (TBD)
2. Secondary components
• Internat heaters
• Thermistors
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3 PROBA – 3 Phase B
Battery Design
1. Main components
• Cells Series (TBD)
• String Parallel (TBD)
2. Secondary components
• Internat heaters
• Thermistors
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How can we
calculate this?
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA – 3 Phase B
Battery Design
1. Evaluate the number of cells ?
• Nominal non regulated bus voltage (28V)
• Cells characteristics (4.2V EoC)
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2.5
2.6
2.7
2.8
2.9
3.0
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
4.0
4.1
4.2
0 10 20 30 40 50 60 70 80 90 100
State of Charge (%)
Ce
ll L
ev
el E
MF
(V
)
Discharge EMF Charge EMF
7 Cells / String
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA – 3 Phase B
Battery Design
2. Evaluate the number of strings ?
• Approach decision
− Battery for both Sun & Eclipse
− Battery for Eclipse only
• Check Power Budget (Wst Case)
− Detumbling (200W / 1hr)
− Eclipse (240W / 30min)
− Long Eclipse (190W / 3.5hrs)
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3 PROBA – 3 Phase B
Battery Design
2. Evaluate the number of strings ?
• Capacityused = Power * Time
• Capacityrequired = CapacityUsed*(1+DoD)
• Capacity of 1 string = NbCells*CapacityCell
• One String Failure Tolerance
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Scenario Used Capacity (Wh)
Detumbling 200
Eclipse 120
Long Eclipse 665
Scenario DoD choice Required
Capacity (Wh)
Detumbling 20% 240
Eclipse 20% 148
Long Eclipse 60% 1064
Parameter Value
NbCells 7
CapacityCell 5,4 Wh
Capacity 1 string 37,8 Wh
29 (+1) Strings
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA – 3 Phase B
U/D Operational Concept Problems
1. Downlink not closed at apogee at Max Rate
2. Uplink not closed at apogee at Max Rate
3. Data not able to be downlinked below 50kkm at max rate (coverage)
4. Data not able to be downlinked at min rate (coverage)
See Link Budget
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3 PROBA – 3 Phase B
U/D Operational Concept Solutions
1. Use more power @ Ground Segment
2. Use more power @ Space Segment
3. Use one/several high gain antenna @ Space Segment
4. Use variable data rate
• Low Rate (Uplink & Downlink) when at apogee
• High rate (Uplink & Downlink) when at perigee
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3 PROBA – 3 Phase B
U/D Operational Concept Solutions
1. Use more power @ Ground Segment
2. Use more power @ Space Segment
3. Use one/several high gain antenna @ Space Segment
4. Use variable data rate
• Low Rate (Uplink & Downlink) when at apogee
• High rate (Uplink & Downlink) when at perigee
119
What is the consequence ?
What is the consequence ?
QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA – 3 Phase B
Final Stack Configuration
1. Occulter Spacecraft
2. Coronagraph Spacecraft
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3 PROBA - 3
How would you now further reduce the cost ?
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QinetiQ Space nv © Copyright QinetiQ Limited 2010
3 PROBA - 3
How would you now reduce the cost ?
ANSWER = Increase the risk !
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QinetiQ Space nv © Copyright QinetiQ Limited 2010
4 Conclusion
Satellite System Engineering
1. Follows the Project Life Cycle
• Starts with Mission Concept
• Prepares System Requirements
• Proposes System Designs based on Trade-Offs (Technical + Programmatics)
• Manufacture the S/C
• Verify Requirements (Review of Design / Analysis / Test)
• Launch it !
2. Iterative Multi-disciplinary approach + Massive Communication
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4 Conclusion
QinetiQ Space
1. Proposes Fast Learning Curve on Satellite Systems
2. Offers possibility to built international network quickly
3. Provides opportunity to be known at the European Space Agency
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