the atmocube project, an educational and scientific satellite at...

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


v

Space Weather Sources


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)


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


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


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


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


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 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


AtmoCube: Functional Scheme 1/2


AtmoCube: Functional Scheme 2/2


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


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)


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)


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


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


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


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!

http://www.stk.com/

Mission Analysis 2/2

Worst conditions TSUN = 3549 s TECL = 2135 s


0 10 150

Sampling

Dosimeter

GPS

Magnetometer

Transmetter

Receiver

OBDH

300


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


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


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)


AtmoCube Attitude Determination


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


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


Signal to Noise ratio Noise temperature, data rate, power, frequency, gains

(antenna), noises, losses,, pointing error

Bit error probability Modulation


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


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


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


Primary Structure Tertiary Structure

Secondary Structure


AtmoCube Structure

P-POD

Thermal Analysis


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



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


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


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!

the atmocube project, an educational and scientific satellite at...

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