2011 07-12 adrian yanes - aalto 1

Aalto-1
The Finnish Student Satellite

Adrian Yanes, Jaan Praks and Aalto-1 Team

http://aalto-1.tkk.fi
http://blogs.aalto.fi/satellite/

History

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Aalto University, Finland
Established in 2010

… Where science and art meet
technology and business.

•  School of Art and Design
•  School of Economics
•  School of Chemical Technology
•  School of Electrical Engineering
•  School of Engineering
•  School of Science

•  20 000 students
•  338 professors

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University Campus in
Espoo
by Alvar Aalto

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University Campus
in Espoo
by Alvar Aalto

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Space Technology at Aalto University
Professorship of Space Technology was established in
1987 in response to Finland joining the European
Space Agency

In Finland M.Sc. and Ph.D. education in Space
Technology is provided only by Aalto University

Aalto University (and previously Helsinki University of
Technology, now part of Aalto University) has
participated in space projects in remote sensing,
material technology, radio astronomy, robotics, etc.

Aalto University presently participates in the European
Erasmus Mundus Space Master degree program and
has international Master’s program in Radio Science
and Space Technology

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Student satellites in TKK (Aalto)

•  1992 – 1995 HUTSAT, several year project,
reached prototype building phase.

•  1992 - 1993 FIMSAT , Finnish remote sensing
satellite, preliminary design.

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Image © ESA

Latest achievements Aalto-1
Aalto University designed SMOS satellite receivers The Finnish Student Satellite

Space as an
Inspiration in
Education
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Motivation and Challenge for Modern
Engineering Student
Space has inspired human beings from the
beginning of civilized times and led us to the
greatest adventures of history.

We attempt to harness this inspiration to promote
the engineering education in Finland and in Aalto
University.

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Student satellites
•  CanSat
•  CubeSat
•  Other designs
•  Constantly growing topic

•  Often open source, open standards, community AAUSAT-II
supported Aalborg University, Denmark

•  Spinoff companies selling parts for Cubesat
systems
•  Cheap launches
•  Nanosatellites < 10 kg

•  OTS mobile electronics to small satellites
•  Whole satellite industry driving towards smaller
size

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AET 2010 course
•  During the spring term 2010 we arranged
experimental course:
•  S-92.3192 Special Assignment in Space Technology
•  “Feasibility study of a Nanosatellite”
•  Teachers Jaan Praks, Antti Kestilä

•  During the course, 7 students made a realistic
preliminary design for the first Finnish
nanosatellite.

•  The course introduced several new concepts in our
teaching
•  The course was project based, all teaching was
given in the form of project meetings.
•  The course was Wiki based, using online
collaboration as a main cooperation tool.

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Starting with wild Ideas

•  Nanosatellite with adjoint picosatellites
•  Biological material in nanosatellite
•  Synthetic aperture radiometer as satellite
swarm
•  Mobile phone in space
•  Synthetic Aperture Radar (SAR)
•  Deep space mission
•  Propulsion test
•  Asteroid mission
•  Cosmic file server

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Refinement of the goal

•  Make realistic preliminary design for first
Finnish nanosatellite

•  Constrains:
•  Design has to be realistic
•  The satellite has to be possible to build mostly
with student work (thesis and special
assignments)
•  Satellite instruments should be made in Finland
(if possible)
•  The satellite main payload and mission should
be related to our department research and
teaching topics

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The Main Payload is Found!

•  The satellite started to shape
when the main payload was
found and selected.

•  Main payload defined
scientific goals and most
mission parameters.

•  The main payload introduced A miniature imaging
also “client” relationship to spectrometer developed in VTT
the project. Technical Research Centre of
Finland
Prototype for usage in UAV

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Main Concept
ü Open standard
Requirements ü Community
•  The satellite has to accommodate hyperspectral camera ü Organization
•  The satellite has to be stabilized ü Platform
•  The best orbit is sun synchronous mid-day orbit ü Education
•  The satellite has to be affordable
•  The satellite has to be usable in education
•  The satellite should have high speed data link
•  There should be common standards for cooperation and
continuity
•  Some subsystems should be available

CubeSat standard based nanosatellite design

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Project

MIDE student project 2011-2013
Project leader Martti Hallikainen International collaboration
Project coordinator Jaan Praks
University of Tartu
Steering group and Science Team TU Delft
CalPoly
Domestic collaboration TU Berlin
etc
Aalto University (4 departments)
VTT Technical Research Centre of Finland
University of Helsinki
University of Turku
Finnish Meteorological institute
Nokia
Aboa Space Research Oy (ASRO)
Oxford Instruments Analytical Oy

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Evolution
of Aalto-1
design
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Science
SPECTROMETER

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World smallest hypespectral camera for
remote sensing applications by VTT

VTT Technical Research Centre of
Finland has developed a tiny
hyperspectral camera suitable for
many applications based on MEMS
Fabry-Perot interferometer.

Aalto-1 provides a test platform to
demonstrate space readiness of this
technology. The Fabry-Perot Interferometer based
hyperspectral hand held imager by VTT

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Fabry-Perot interferometer working
principle
Fabry-Perot Mirrors
Object of the Image of the
hyperspectral hyperspectral
imager imager

Front optics
for collimation Focusing optics
Order sorting for imaging
filter Air gap

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Current model for UASI

Major specifications of the spectral camera
Spectral range: 500 – 900 nm
Spectral Resolution: 9..45 nm @ FWHM
Focal length: 9.3 mm
F-number: 6.8
Image size: 5.7 mm x 4.3 mm, 5 Mpix
Minimum total exposure time: 30 ms
Field of View: 32° (across the flight direction)
Ground pixel size: 3.5 cm @ 150 m height
Weight: 350 g (without battery)
Size: 62 mm x 61 mm/76mm x 120 mm
Power consumption: 3 W

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VTT miniature spectrometers UASI test flights Aalto-1

Satelliteborne hyperspectral remote sensing
•  Vegetation
•  Water quality
•  Geology
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Science
PLASMA BRAKE

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Solar photon sail
§  Each solar photon carries momentum, doubled if
reflected
§  About 9 uN/m2 thrust density for perfect mirror
§  At 1 AU, 1 N sail would be 330x330 m, membrane
mass 1200 kg if made of 7.6 um polyimide sheet,
characteristic acceleration 0.8 mm/s2
§  Thrust vectoring is possible, but thrust magnitude
and direction change in unison for flat sail
§  Solar sail is old idea (roughly 100 years), implemented
in space first time in 2010 (IKAROS, Japan)
§  Technical challenges of solar sail:
–  Membrane should be very thin
–  Membrane's support structures should be very lightweight
as well
–  Everything must be tightly packaged and folded during
launch

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Electric solar wind sail
§  Solar wind
–  Plasma stream emitted from Sun in all directions
–  Speed 350-800 km/s (lowest in ecliptic plane,
higher elsewhere)‫‏‬
–  Mean density 7 cm-3 at Earth
–  Variable, but always present
–  Dynamic pressure ~2 nPa at Earth (1/5000 of
photon pressure)‫‏‬
§  Electric sail (E-sail)‫‏‬
–  Slowly rotating system of long, thin, conducting
and centrifugally stretched tethers which are kept
positively charged (~ +20 kV) by spacecraft
electron gun
–  Only modest amount of electric power needed,
obtained from solar panels
–  ~500 nN/m thrust per length
–  For example, 100x20 km tethers, 1 N thrust, 100
kg mass, specific acceleration 10 mm/s2

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E-sail, traveling in interplanetary space without fuel Aalto-1

Electrostatic Plasma Brake

Electrostatic Plasma Brake is designed as an “end of life”
mission to bring satellite after service down.

Based on Electric Space Sail concepts by Pekka Janhunen (FMI)

Developed and produced by
Finnish Meteorological Institute (FMI)

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Image © ESA

20 000 pieces trackable space junk orbits the Earth Aalto-1

Science
RADiation MONitor

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Radiation environment in Earth orbit

•  Radiation in LEO is the most
significant threat to
electronics.

•  Need for simple and small
radiation detector.

•  Trapped proton environment
on LEO needs to be taken
into account in the design of
any spacecraft.
Trapped proton environment anisotropies

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Payloads:
Radiation Monitor University of Helsinki

•  Sensor unit based on Si detector and
CsI(TI) scintillator
•  Readout electronics consist of a
pulse shaping and peak-hold
circuitry with a pre-amplifier signal
being digitised with high sampling
rate
•  FPGA based logic to count particle
events hitting the sensor

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BepiColombo SIXS
BepiColombo is ESA mission to Mercury. Spacecraft will set off
in 2014, arrives to Mercury 2020, planned operation till
2022. Onboard will be the pioneering SIXS instrument (Solar
Intensity X-ray and particle Spectrometer) developed in a
Finnish consortium. The main task of SIXS is to provide
observations of X-ray and particle radiation on Mercury’s
surface.

Consortium: Finnish Meteorological Institute, FMI (project
managing, FPGA coding, EGSE design), Space Systems
Finland Oy, SSF (software, systems engineering), Ideal
Product Data Oy (thermal modelling) and Patria Oyj (Digital
Processing Unit). The collaboration includes also UK
Illustration: Oxford Instruments
contribution by the Rutherford Appleton Laboratory, RAL Analytical OY
(readout ASIC for the particle detector system), Oxford
Instruments Analytical OY

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TECHNOLOGY

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Launch is most critical part of the
mission
Static acceleration
Shocks and vibrations
–  Recall problems with Space Shuttle tiles!
Acoustic stress
Declining pressure
Temperature changes

Satellite has to be strong

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Extreme speed and distance make
communication difficult

Extremely big variability in speed and distance during the lifespan
of spacecraft

Signal attenuation

Dopler effect

Ionospheric effects
Nasa Deep Space Network

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Space environment:
Electromagnetic radiation

•  The Sun is a variable star
–  Strong variations at short (UV, X, gamma) and
long (radio) waves

•  Black space is cold
–  The illuminated side gets heated, the opposite
side radiates the heat (IR) and cools
–  Thermal design is very tricky
•  Extreme example: BepiColombo between
the Sun and Mercury

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Cosmic radiation
Cosmic rays are very energetic charged particles
•  Galactic: > 100 MeV
•  Solar: < 1 GeV
•  Anomalous: around 10 MeV
–  Note these energies are much higher than the
energy of solar wind particles

Cause single events in electronics

Most energetic cosmic rays penetrate through the
Earth’s magnetic field and are stopped in the
atmosphere causing air showers

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Vacuum, there is no air

No air means that there is no convection.

The only heat exchange way is radiation

Nothing to grab, you cannot fly

Some materials can just evaporate

Very tricky to lubricate mechanisms

There is no electrical conduction, a satellite can
build up static electric charge which can damage
electronics

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Micrometeoroids and space debris

Debris is a growing concern
•  20,000 pieces larger than 10 cm
•  500,000 in the range 1 – 10 cm
•  Tens of millions smaller pieces
Large relative speeds – large momentum in
collisions
Sources
•  Old satellites
•  Left-overs from lauchers,pieces of surface
materials and paint, etc.
•  Collisions, e.g., Kosmos-2251 – Iridium 33
collision in February 2009
Micrometeoroids
•  ”Natural space debris”

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Satellite subsystems

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Aalto-1 satellite
Based on CubeSat 3U standards (34cm×10cm×10 cm)

Weight: 3 kg.
Orbit: Sun-synchronous mid-day LEO .
Attitude control: 3 axis stabilized.
Communication: VHF-UHF telecommand
S-band data transfer.

Solar powered, max power 8 W.

Payloads:
Imaging spectrometer (VTT).
Radiation detector (HY, UTU).
Electrostatic Plasma Brake (FMI).

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Mechanical structure

The new mechanical structure is
under development

Base model for subsystems

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Mechanical structure

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Antennas

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System design

•  CubesatKit PCB layout and
Connector

•  RS-422 / LVDS for all the
interfaces

•  PicoADACS (BST/Delft)

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System design

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Bus interface/protocol

•  Bus is created with stack-trough connectors (CubeSatKit).

•  Bus is used for all electrical connections (power, data).

•  3.3V, 5V and 12V available.

•  Data interface will be differential system (RS-422/LVDS).

•  I2C will be used for zombie control.

•  Separate pins for all data connections => star topology

•  Separate kill switch pins?
4/20

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System Design
Legend:
Data Interfaces ____
Power Interfaces ____
Thermal Interfaces ____
Sensors Mechanical Interfaces ____
Control
System
Actuators
Spectrometer
Attitude Determination and Control
System ADCS
Ground
Computer
System GCS
GPS Onboard Mission
GPS module Radiation Monitor
Antenna Computer Database
OBC Tracking
Orbit Determination System

Command and Command and Data Handling
B
UHF-VHF UHF-VHF e Data Handling
Antennas Transceiver a System
c Electrostatic
o Plasma Brake
n Modem
Modem
Payloads

S-band Thermal System Receiver
S-band
Antenna Transmitter

Communication System S-band UHF-VHF
Antenna Antennas

Communication Subsystem
Housekeeping Structural System
Batteries
Power Ground Segement
Regulation
Solar Panels and Control

Power System

Satellite Segment

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3/20

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Electrict Power System

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Power generation

•  Energy generated via solar cells.

•  Average power (eclipse included) is ca. 4.7 W
–  No panels on nadir-side, 6 panels on other sides.

•  A crude simulation for 15 orbits (ca. 1 day) has been
done.
–  It seems like we have plenty of energy.
–  However, fully charging the batteries (20Wh) will take around
6-7 orbits in power saving mode.

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Energy Budget

Energy budget simulations for optimal
attitude and orbit

Direct Earth Total
Sun
Polar 7.7 W 0.51 W 8.21 W
45 deg 7.7 W 0.51 W 8.13 W
Average 7.7 W 0.51 W 8.17 W

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Orbit

Mid-day Sun-synchronous orbit would be preferable for main instruments.

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On Board Data Handling Hardware

Based on ARM920T 180MHz

RAM: 256MB (ECC)

Mass-storages:

•  OS (~256MB)

•  Data (1GB)

Interfaces:
SSP/I2SI2C/SPI/61 GPIO/JTAG

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Data System

Single Board Computer as a central
computer

Separate DSP

Digital Signal Processing performed
onboard in order to reduce the downlink
data stream

Backup system is based on
microcontrollers and is able to re-flash
the system

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Software

•  OS: GNU/Linux
•  Client-server architecture for payloads
•  ASM / C / C++ (µlibc).
•  Really tiny and tested.
•  Designed to run in user space.
•  Dispensable.
•  Extensible from Earth (re-programming).

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Software

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Kernel & OS

–  Highly customized: focused in I2C and process scheduling.
–  Real-time patches (http://www.kernel.org/pub/linux/kernel/
projects/rt/)
–  OpenEmbedded as basement for the distro.
–  Deterministic system.
–  Autonomous: non human-interaction needed.
–  Inter-process communication: D-Bus.

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Ground station

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Ground station

Location: Espoo, Finland

Coordinates: 60.188444N, 24.829981E

UHF operational from July 2011!

Future equipment (really soon):

-S-band antenna
-VHF – antenna
-Receivers and transmitters & tracking mechanisms.

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Telecommunications

VHFdownlink /UHF uplink
S-band Downlink

Link duration per day – simulation for selected orbit

Min. Duration 65.313 sec
Max. Duration 637.889 sec Transreceiver VHF downlink/UHF S-band downlink
Avg. Duration 475.298 sec examples uplink
Frequency 130-160 MHz 2100-2500 MHz
Total Duration 14258.926 sec RF output 300 mW PEP / 150 500 mW
mW average
Power consumption 1,7 W/0,2 W 2W
Data transfer up to 9,6 kbps up to 115 kpbs
Mass 85g <125g
Size 90mmx96mmx40m 90mmx96mmx40m
m m

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STATUS
and
COMMUNITY
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Tightly integrated with teaching

The satellite project is tightly integrated with teaching, it
will be designed and constructed as a part of special
assignment courses and thesis works, supported by
Space Technology and Radio Engineering main subject
teaching.

The satellite project brings together a consortium of
Finnish space industry and Finnish top universities for
the benefit of our students.

The project has involved already five departments in
Aalto University

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Active students

Student activities are
important part of the project.

Learning can be fun!

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Meeting people

Part of student satellite team meeting with NASA astronaut Timothy Kopra

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Learning together

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Conferences and Workshops

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Participating Conferences Aalto-1

Proto-storm 18.3.2011 Aalto-1

Gracias!
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2011 07-12 adrian yanes - aalto 1

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2011 07-12 adrian yanes - aalto 1