the atmocube project, an educational and scientific satellite at...
TRANSCRIPT
The AtmoCube project, an educational and
scientific satellite at the University of Trieste
In collaboration with:
INAF, INFN, Area Science Park, Mathitech, Enteos, Elcon, Elimos, Scen, Sicom
http://www.units.it/atmocube [email protected]
how everything can be fitted in 10 cm!!! and in a few years…
Overview
Scientific Rationale: Space Weather
AtmoCube Satellite
AtmoCube Systems
Status
Team
Conclusions
Milano 12.01.2012 The AtmoCube Mission 2
Space Weather Effects 1/2 The complexity of the physical environments that influence,
and of those who are influenced by, space weather conditions make modeling and prediction of the phenomenology quite challenging
Models: Solar Cycle 24 (NOAA, NASA, ISES)
54 different predictions based on climatology, dynamo models, spectral analysis, neural networks, geomagnetic precursors, solar precursors
PROLONGED MINIMUM NOT PREDICTED!
Both physics-based and statistical models require the availability of long term, multi-wavelength observations to get significant improvements
Nanosatellites can be built and launched with unusual low budget for space missions and can be used for long-term monitoring of the Sun and the Earth atmosphere
Milano 12.01.2012 The AtmoCube Mission 3
v
Space Weather Sources
Milano 12.01.2012 The AtmoCube Mission 5
SPACE WEATHER SOURCES
SUN
SOLAR SYSTEM
HIGH ENERGY SOURCES
NON-NATURAL SOURCES
ELECTROMAGNETIC RADIATION
SOLAR ENERGETIC PARTICLES
CORONAL MASS EJECTIONS
SOLAR WIND STREAMS
NEAR EARTH OBJECTS
INTERPLANETARY DEBRIS
GAMMA RAY BURSTS
COSMIC RAYS
MAN-MADE DEBRIS
Messerotti (2010)
Milano 12.01.2012 The AtmoCube Mission 6
AtmoCube Scientific Case
SU
N
INTERPLANETARY MEDIUM
AT
MO
S
PH
ER
E
Flare 8 min X, UV • Enhanced ionization: SID
• Heating + expansion: Drag
Protons mins-hrs • Enhanced ionization @poles: PCA • Enhanced particle level in ixMagnetosphere
CME hrs-days • Current system perturbation: xiGeomagnetic Storm
Fast S.W. Streams hrs-days • Ring currents perturbation: xiGeomagnetic Storm
Prominence
Coronal Hole
Messerotti (1999, 2001)
Radiation Flux Atmospheric Density Magnetic Field
Active Sun
Milano 12.01.2012 The AtmoCube Mission 7
The AtmoCube Mission: Executive Summary
A satellite for:
Involving students in a real Space Mission
Studying the Space Weather through: Radiation flux (soft X-rays, protons): Silicon
Detector Earth magnetic field: Magnetometer Atmospheric density: GPS
Prototyping very low cost scientific applications
Prototyping very low cost space applications
Constraints: Cubesat specifications (1 kg, 10 10 10 cm, I/F ...)
ESA: CubeSat on Vega Maiden Flight
Milano 12.01.2012 The AtmoCube Mission 8
In 2008 ESA Education Office issued a Call For CubeSat Proposals to universities in ESA Member and Cooperating States
Vega Maiden Flight: 2012
AtmoCube among the 9 selected proposals
Milano 12.01.2012 The AtmoCube Mission 9
AtmoCube
A cube of about 10 cm (compatible with P-POD requirements, 336 g)
Five boards (416 g) RF board for TC Power supply Battery & magnetometer OBDH Silicon detector
Solar array (146 g) Antenna (100 g) Total mass 998 g (15% margin included)
Satellite Systems
Milano 12.01.2012 The AtmoCube Mission 10
AtmoCube: Satellite System Matrix
Milano 12.01.2012 11
ORBITA
altezza,
inclinazione
dose radiazione
campo magnetico
.
campo magnetico
densità atmosfera
.
durata giorno e
notte
.
trasmissione,
distanza stazione
.
STRUMENTO
SCIENTIFICO
dosimetro, GPS,
magnetometro
stabilità
puntamento
.
consumo
.
massa
centro di massa
.
mole dati
.
ASSETTOposizione celle
.
massa
centro di massa
.
mole dati
.
ALIMENTAZIONE
celle solari, batterie
trasmissione
.
massa
centro di massa
.
consumo
.
TELECOM
antenna bordo,
terra
massa
centro di massa
.
telecomandi
trasferimento dati
.
perturbazioni
orbitali
perturbazioni
orbitali
perturbazioni
orbitali
STRUTTURA
.
,
mole dati
.
.
,
consumo
.
dati scientifici
housekeeping
COMPUTER
BORDO
The AtmoCube Mission
AtmoCube
Analysis process Scientific Measurement: “Space-Weather” analysis
Measurement of the Radiation Flux impinging on the satellite
Measurement of the Magnetic Field in which the satellite is plunged
Problematics
Low cost: very easy, small and light system
Quasi-standard structure - CubeSat-like, cube of 10 cm side, mass 1 kg, power ~3 W, flexible structure with interchangeable instrumentation, avoid moving parts (mechanisms) if possible
Use of any available launcher: non-optimized orbit
Commercial, non dedicated instrumentation
Low accuracy, limited data rate (radio-amateur band)
Avoid measurement interference (magnetic field)
Limited usage of electro-magnetic systems (coils)
Keep instrumentation far away from electronics: satellite modulation
Satellite attitude control: Magnetic Torquer, Gravity Gradient Boom
Milano 12.01.2012 The AtmoCube Mission 12
Milano 12.01.2012 13
Planning of a Space Mission
Fase A Fase B Fase C
- feasibility study - simulations -engineering aspects
-scientific aspects
- costs technical &
scientific specifications to institutes/industries
Fase D
- final design - construction - test
QM - Structural Model - Electrical Model (EMC) - ….
FM
The AtmoCube Mission
Milano 12.01.2012 The AtmoCube Mission 14
AtmoCube: Functional Scheme 1/2
Milano 12.01.2012 The AtmoCube Mission 15
AtmoCube: Functional Scheme 2/2
Milano 12.01.2012 The AtmoCube Mission 16
Payload A: Radiation Flux -not implemented
The Radiation Environment Soft X-rays (up to 70 keV)
Charged particles (protons E>70 keV)
A Silicon Drift Detector to measure these fluxes (<100 Hz), active area 1 cm2, based on an analog front-end followed by digital processing (FPGA)
Provided by INFN (National Institute for Nuclear Physics)
Added value: test-bed for future space missions
Milano 12.01.2012 The AtmoCube Mission 17
Payload A: Radiation Flux 2/2
Challenging features:
Signal to Noise ratio (energy resolution)
Speed (charge sensitive amplifier response time ~20 ns)
Low power consumption (target < 300 mW)
Fully designed by students, development ongoing: Analog front-end (almost complete and functional)
FPGA firmware (development on going) custom bread board (already designed)
Milano 12.01.2012 The AtmoCube Mission 18
Radiation Effects
SPENVIS - Proton and Electron models to evaluate:
Dose at the centre
of an Al sphere as a
function of Al thickness
0 5 10 15 20 Al absorber thickness (mm) 0.1 1.0 10.0 100.0 1000.0
Energy (MeV)
Shielded solar proton
spectrum
108
1012
109
1010
1011
Inte
gra
l F
lue
nce (
cm
-2)
10-10
1010
10-5
100
105
Do
se in S
i (r
ad)
Milano 12.01.2012 The AtmoCube Mission 19
Radiation Effects: G4 Simulation
Geant4 Full Simulation
satellite complete GEANT4 mass model with real geometry (Magnetometer, GPS, OnBoard Data Handling, Power Unit, Radio included)
same simulation interfaced through ESA General Particle Source Module to SPENVIS output
Results used to evaluate the screening of the components and to simulate the real data stream received from the satellite
Milano 12.01.2012 The AtmoCube Mission 20
Payload B: GPS - not implemented
Atmospheric Density
variable Solar minimum Solar average Solar maximum
adrag (m/s2) -2.9 10-6 -8.8 10-6 -2.1 10-5
a /revolution (m) -4.9 -14.5 -34.6
e /revolution -6.1 10-7 -1.8 10-6 -4.3 10-6
GPS RECEIVERS FOR SPACE (CLYDE SPACE)
-PCB ready to be assembled & tested
-Firmware for GPS & Magnetometer
communication under development
Added value: test-bed for future space missions
Milano 12.01.2012 The AtmoCube Mission 21
Payload C: Magnetic Field Sensor
Earth Magnetic Field variations
Solar conditions 0.5%
Day/night 0.15%
Season 0.15%
HMC2003 magnetometer
Accuracy 4 10-10 T, range 40 G 2 G
Size 25.4 19.1 mm, mass 4 g, power 120 300 mW
Magnetic Field
(T·10-4)
Bmax Bmin Bmax Bmin Bmax Bmin
Emisphere @350 km @600 km @1,200 km
North 0.5198 0.2990 0.4629 0.2087 0.3834 0.1433
South 0.5634 0.1989 0.4999 0.1801 0.3803 0.1457
B=B0(RT/Rm)3 1+3 sin2m
Milano 12.01.2012 The AtmoCube Mission 22
Mission Analysis
Radius (km) 7153.14
semi-major axis
6728.14
@perigee
7578.14
@apogee
Velocity (km/s) 7.458
average
7.922
@perigee
7.034
@apogee
Eccentricity 0.0594
Inclination 71o
Mean motion (rad/s) 0.00104
Period 6020.8 s
(100.35 min)
Number of orbits/day 14.3
(node shift/orbit due to
Earth rotation)
-25.09 deg/orbit
(-358.96 deg/day)
Eclipse phase duration (s) 2008
(average)
2110
(max)
Visibility at Ground Station (s) 403
(average)
678
(max)
Visibility gap (s) 24,388
(average)
84,053
(max)
4,974
(min)
Satellite Tool Kit - STK www.stk.com
Scientific requirements:
Low orbit (h 800 km),
High inclination (i 60 )
Technical requirements: Visibility ground station (h >>)
VEGA!
Mission Analysis 2/2
Worst conditions TSUN = 3549 s TECL = 2135 s
Milano 12.01.2012 The AtmoCube Mission 23
0 10 150
Sampling
Dosimeter
GPS
Magnetometer
Transmetter
Receiver
OBDH
300
Milano 12.01.2012 The AtmoCube Mission 25
Power System: Power Supplies 1/2
Switching Converters are employed when the voltage is larger than battery voltage
An LDO (Low Drop Out) converter is used to obtain +3.3 V
Very simple architecture, high reliability, current mode battery recharge
…
+7V
Milano 12.01.2012 The AtmoCube Mission 26
Power System: Power Supplies 2/2
PA Power Supply Step-up DC/DC converter (7V, 1A) using LTC3428
Linear Technology (already developed)
600V Power Supply Low noise – 600V power supply for particle detector
using low noise Royer DC/DC converters with feedback (currently under development)
Key factors are: Low output current (<1 mA)
Low output noise
High voltage isolation
Switching noise reduction
Attitude Control & Determination
Milano 12.01.2012 The AtmoCube Mission 27
A satellite must maintain a certain attitude while in orbit to allow precise pointing of an antenna toward the Earth to allow the accurate orientation of observation instruments toward the object being observed to direct solar panels toward the Sun But the satellite receives interference from such phenomena as the Earth's gravitational and magnetic fields, and the solar wind. These phenomena tend to disturb the satellite's attitude, so it is necessary to control attitude to keep the satellite stable. http://spaceinfo.jaxa.jp/
AtmoCube Attitude Control
Magnetic Torque
Permanent magnet (passive)
Alnico (Aluminum, Nickel, Cobalt): high temperature stability 0.02% /oC
Magnetic coils (active)
Milano 12.01.2012 The AtmoCube Mission 28
AtmoCube Attitude Determination
Milano 12.01.2012 The AtmoCube Mission 29
GPS
Solar Cells
Photodiodes
3-dim Magnetometer
SENSORS
Earth
Sat Sun
-180 -90 0 90 180
-
fov/2-
-fov/2
Solar Cells current
Photodiodes
Telecom: Link analysis
Milano 12.01.2012 The AtmoCube Mission 30
Transmitter EIRP
Receveir G/T
S
][W/m 4
2
2r
PP T
R ][W/m 4
2
2r
GGPP RTT
R
Isotropic antenna
Directive antenna
Uplink & Downlink
Analysis: data rate, power, frequency, gains (antenna), noises,
losses, modulation, pointing error VS bit error probability
Telecom: Link analysis
Milano 12.01.2012 The AtmoCube Mission 31
Signal to Noise ratio Noise temperature, data rate, power, frequency, gains
(antenna), noises, losses,, pointing error
Bit error probability Modulation
Milano 12.01.2012 The AtmoCube Mission 32
On Board Radio
Provide modulation - demodulation of FSK signal
Provide enough RF power to ensure reliable communication
Pay attention to efficiency (38%)
With up to 6 dBW of RF power available, minimum margin is 7 dB (downlink only): science measurements every 300 s
(20 per orbit) 10 orbits max visibility gap 9,600 bps rate time required for downlink: 250 s
Milano 12.01.2012 The AtmoCube Mission 33
On-board Data Handling
OBDH is responsible of the management of the system: Acquire data from HK sensor to monitor S/C functionality System management (manage the activity of systems, collect data from sensors and store values in memory) Manage the connection to the ground station
SILICON DETECTOR
MAGNETOMETER PHOTODIODES GPS
MEMORY TRANSCEIVER
POWER MANAGEMENT
HOUSEKEEPING SENSORS
OBDH
Milano 12.01.2012 The AtmoCube Mission 34
AtmoCube OBDH
RAM MEMORY
(2MB)
POWER
MANAGEMENT
CPU (PIC -controller)
SPI SILICON
DETECTOR MAGNETOMETER
PHOTODIODES GPS RADIO MUX
AtmoCube modes:
Mechanical Structure Sustain all different satellite elements
Protection from external environment
Antenna deployment or additional moving mechanism
Control and absorb dangerous vibration for the instrument (launch)
Guidelines
Easy access to all components: symmetric and modular structure
Launch: massive components close to, sensitive components far away from launcher
Eletcrical components all close together, components sensitive to contamination faraway from thrusters, propellant close to CoM, solar panels and components sensitive to temperature simmetriycally distribuited, minimize appendices
Milano 12.01.2012 The AtmoCube Mission 35
Primary Structure Tertiary Structure
Secondary Structure
Milano 12.01.2012 The AtmoCube Mission 36
AtmoCube Structure
P-POD
Thermal Analysis
Milano 12.01.2012 The AtmoCube Mission 37
Sole
Earth
Satellite
direct solar flux Gs
indirect solar flux a 34%
internal heat
Earth IR radiation qi
237 W/m2
emitted radiation
TMAX (9 33) C
TMIN -(96 119) C
SISTEMS TMIN ( C) TMAX ( C)
Battery charge
discharge
0
-40 50
60
Dosimeter -20 40
QABSORBED - QCELLS + QGENERATED = QIRRADIATED
Ground Segment: INAF-OATS Basovizza
Assigned frequency by IARU
437 MHz (radio amateur band)
Renewal of the equipment
Yagi-Uda Antenna 11 and 19 elements
Rotors and coaxial cables
Ground Station subsystems hosted at National Institute for AstroPhysics – Astronomical Observatory – Trieste
GENSO
Milano 12.01.2012 The AtmoCube Mission 38
Milano 12.01.2012 The AtmoCube Mission 39
AtmoCube Development Status
Design Manufacturing
Silicon Detector 70% 45%
Magnetometer & GPS 95% 45%
Attitude C&D 100% 90%
Mechanics 100% 90%
Power Supply 100% 90%
On board Radio 100% 95%
Ground Station 95% 50%
OBDH HW 100% 95%
OBDH SW 100% 80%
ATMOCUBE
ATMOCUBE DEADLINE
NIGHTMARE
ATMOCUBE
ATMOCUBE DEADLINE
NIGHTMARE
Milano 12.01.2012 The AtmoCube Mission 40
The AtmoCube Team
Principal Investigator Anna Gregorio Co-Investigator Sergio Carrato Project Manager Mario Fragiacomo
Alessandro Cuttin AtmoCube Scientist Mauro Messerotti Steering Committee AG, SC, MF, AC, MM, W. Bonvicini, L. Bregant, A. Vacchi
AtmoCube Development Team 14 senior physicist and engineers >35 students 2+1 fellowships
Up to now >35 theses in AtmoCube
Small/Medium Enterprises • MatHiTech • Enteos/Mywave • Elcon • Others
Milano 12.01.2012 The AtmoCube Mission 41
Funding… Common problem, common effort? Starting…
Great educational tool Possible great scientific tool…
Additional values: Prototyping very low cost scientific and space applications Involvement of industries for job opportunities for students and
possible technological transfer
Draw backs: Students usually available for a short period (1-2 years) Some students too involved and forget about exams
Readiness … Hopefully Mid 2012
Next AtmoCube??? QB50 (FP7), …
Conclusions
Thanks for your attention and… … enjoy!