Report

Transcription

Report

Minor Project – Fall 2012
HAGARE Report – Phase 0/A
High Altitude Gamma-Rays Experiment
Issue 1
Prepared by
Supervised by
Thibault Kuntzer
Dr. Anton Ivanov, anton.ivanov@epfl.ch
thibault.kuntzer@epfl.ch
Eleonie van Schreven
eleonie.vanschreven@epfl.ch
Thibaud Humair
thibaud.humair@epfl.ch
23 January 2013
HAGARE Project Report
AAD
A/D
AIT
AGN
APRS
BEXUS
C&DH
CDR
CoM
CPU
CR
EAR
E-Link
EBASS
EPS
ESA
ESRANGE
DoD
DPU
DSU
GND
GNSS
GRB
IPR
LPHE
LT
OBC
PSU
SCU
SED
SMA
SSC
SiPM
TBD
TC
T/M
TOF
TRD
VLK
VV
Issue 1
Attitude and Altitude Determination
Analog to digital
Assembly, Integration and Testing
Active Galactic Nuclei
Automatic Packet Reporting System
Balloon Experiments for University Students
Command and Data Handling
Critical Design Review
Center of Mass
Central Processing Unit
Cosmic Rays
Experiment Acceptance Review
BEXUS Ethernet up and downlink
ESRANGE Balloon Service System (control and piloting system)
Electrical Power Subsystem
European Space Agency
European Sounding Rocket Launching Range
Depth of Discharge
Data Processing Unit
Data Storage Unit
Ground
Global Navigation Satellite System
Gamma-Ray Burst
Integration Progress Review
Laboratoire de Physique des Hautes Energies / EPFL
Local Time
On-Board Computer
Power Supply Unit
Slow Control Unit
Student Experiment Documentation
SubMiniature connector version A
Swiss Space Center
Silicon Photo-Multiplier
To Be Determined
Tele-command
Telemetry
Time-of-Flight detector
Transition Radiation Detector
Verordnung über Luftfahrzeuge besonderer Kategorien
Vertical Visibility
Table 1: Abbreviation Table
Issue
Date
Author(s)
Changes
1
20/01/2013
TK & EvS
Version 1 issued
Table 2: Change List
Swiss Space Center / LPHE
page 2 of 67
Issue 1
Contents
1
Motivations
1.1 Experiment objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.1.1 Primary objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.1.2 Secondary objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
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2
Responsibilities
2.1 Organisation of the Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2 Team Members . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3 Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5
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3
Fundamental of Astroparticles Physics
3.1 Cosmic rays : an historical overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2 Photons in cosmic rays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6
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7
4
HAGARE Concept
4.1 The BEXUS concept . . . . . . . . . . . . . . . . . . .
4.1.1 The BEXUS Flight system . . . . . . . . . . .
4.1.2 The Selection . . . . . . . . . . . . . . . . . .
4.1.3 The Pre-Flight . . . . . . . . . . . . . . . . . .
4.1.4 The Flight . . . . . . . . . . . . . . . . . . . .
4.1.5 The Recovery . . . . . . . . . . . . . . . . . .
4.1.6 Post-Flight Activities . . . . . . . . . . . . . .
4.2 BEXUS Requirements . . . . . . . . . . . . . . . . . .
4.2.1 Mechanical Requirements . . . . . . . . . . .
4.2.2 Thermal Requirements . . . . . . . . . . . . .
4.2.3 Electrical Requirements . . . . . . . . . . . .
4.2.4 Telemetry and Tele-command . . . . . . . . .
4.3 REXUS/BEXUS – EPFL Heritage . . . . . . . . . . .
4.3.1 PERDaix . . . . . . . . . . . . . . . . . . . . .
4.3.2 GGES . . . . . . . . . . . . . . . . . . . . . . .
4.4 General description of the detector . . . . . . . . . .
4.4.1 Gamma-Ray Detector . . . . . . . . . . . . .
4.4.2 Measurements and Further Investigations .
4.5 Technological Development . . . . . . . . . . . . . .
4.5.1 Scientific Payload . . . . . . . . . . . . . . . .
4.5.2 Attitude and Altitude Determination (AAD)
4.5.3 Thermal Control . . . . . . . . . . . . . . . .
4.5.4 Command & Data Handling (C&DH) . . . .
4.5.5 Electrical Power Subsystem (EPS) . . . . . .
4.6 End-to-End Mission Summary . . . . . . . . . . . .
4.6.1 Assembly, Integration and Testing (AIT) . . .
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page 3 of 67
4.6.2
5
Issue 1
Flight Campaign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SHAGARE – Meteorological Balloon Sized Experiment
5.1 Motivation and Requirements . . . . . . . . . . . . .
5.2 Science Instrument . . . . . . . . . . . . . . . . . . .
5.3 Avionics and Hardware . . . . . . . . . . . . . . . .
5.3.1 Trackuino Capabilities Analysis . . . . . . .
5.3.2 Housekeeping Architecture Proposal . . . .
5.4 Software . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.1 Initialisation Mode . . . . . . . . . . . . . . .
5.4.2 Flight Mode . . . . . . . . . . . . . . . . . . .
5.4.3 Power Save Mode . . . . . . . . . . . . . . .
5.4.4 Safe Mode . . . . . . . . . . . . . . . . . . . .
5.5 Trade-Off Evaluations Criteria . . . . . . . . . . . . .
5.6 Testing & Validation . . . . . . . . . . . . . . . . . .
5.6.1 Testing Plans . . . . . . . . . . . . . . . . . .
5.6.2 First Validation of the Concept . . . . . . . .
5.7 End-to-End Mission Summary . . . . . . . . . . . .
5.7.1 Assembly, Integration & Testing . . . . . . .
5.7.2 Pre-Launch . . . . . . . . . . . . . . . . . . .
5.7.3 Flight Campaign . . . . . . . . . . . . . . . .
5.7.4 Post Flight Activities . . . . . . . . . . . . . .
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20
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Bibliography
40
Appendices
41
A BEXUS Proposal
42
B Contact List
58
C SHAGARE Avionics Schematics
C.1 Boards Layouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C.2 Schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C.3 List of Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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D Example of a Trade-off
67
page 4 of 67
Chapter
Issue 1
1
Motivations
This report focuses on semester project done during the autumn semester of 2012 at the Swiss Space
Center (EPFL). We describe here the phase 0/A of the
HAGARE project (High Altitude Gamma-Rays Experiment) which is a collaboration between the Swiss
Space Center (SSC) and the Laboratoire de la Physique
des Hautes Energies (LPHE) for the Teaching Bridge
project.
The atmosphere protects us from high energy particles
present in cosmic rays. Even if this is primordial for
life on Earth, when one wants to study cosmic rays
it becomes a problem. But as the altitude increases,
the atmosphere thins and thus the flux of particles increases. This is especially true for gamma rays. One
can show that the photon flux at altitude lower than 15
km is too low to be detected, thus the need for an high
altitude experiment arose. But even so the flux is still
very low, requiring that the experiment stays at least
a few hours in high altitude. Combining those two
constraints, aircrafts are ruled out and rockets being
very expensive and having a too short flight duration,
we turn to high altitude balloons.
In this context EPFL participated in a first experiment
involving a balloon : PERDaix (Proton Electron Radiation Detector Aix-la-Chapelle), and is designing its
follow-up PEBS (Positron Electron Balloon Spectrometer). Both those experiments focus on charged particles
in cosmic rays and on the ratio between electrons and
positrons.
The present project specializes in the study of gamma
rays in cosmic rays. Just as for PERDaix, we aim at
using the BEXUS/REXUS program that allows student
to send experiments on board of balloon and rockets.
This report studies the feasibility of such a project and
the future studies that will have to be done.
We will start by a description of the BEXUS program
and its requirements, before depicting the HAGARE
project. During the elaboration of this project, the need
to start with a smaller balloon (SHAGARE) arose. We
will explain this need and describe SHAGARE in detail.
1.1
1.1.1
Experiment objectives
Primary objectives
The primary objective are critical for the mission safety
and for its partial success.
ID
OBJ 1
OBJ 2
Objectives
Record gamma particles at an altitude
higher than 25 km, store the energy of the
detected particle on non-volatile storage
device and recover this device post flight.
Download at least 50% of the science and
housekeeping data during the flight.
Table 1.1: Primary Objectives
1.1.2
Secondary objectives
The secondary objectives are critical for a full success
of the mission.
ID
OBJ 3
OBJ 4
OBJ 5
OBJ 6
Objectives
Record gamma particles at an altitude
higher than 30 km for at least 2 hours, store
the energy of the detected particle on nonvolatile storage device and recover this device post flight.
Record temperatures and pressure of critical components all along the flight
Recover the payload intact
Download all the science and housekeeping data during the flight.
Table 1.2: Secondary Objectives
page 5 of 67
Chapter
Issue 1
2
Responsibilities
2.1
Organisation of the Project
This project was carried out in the framework of
the Teaching Bridge Project of EPFL. The aim of the
teaching bridge is to make students and laboratories
from different backgrounds work together on common
projects. The present HAGARE project requires skills
in physics and in engineering. This near-space project
is therefore carried out by the Swiss Space Center (SSC)
and the Laboratoire de Physique des Hautes Energies
(LPHE). The senior supervisors are :
LPHE Prof. Aurélio Bay, aurelio.bay@epfl.ch
SSC Dr. Anton Ivanov, anton.ivanov@epfl.ch
2.2
Team Members
Thibaud Humair
Thibauld Humair is a first year master student who
focuses on particle and theoretical physics. In the
framework of the Teaching Bridge Project and his term
project “Travaux Pratiques IVa”, he worked within the
Laboratoire de Physique des Hautes Energies (LPHE)
to precise the science of the experiment and carried
out the study on the detector concepts.
Thibault Kuntzer
Eleonie van Schreven
Eleonie van Schreven is a second master student doing
her minor in Space Technologies. Her major is also
in Physics oriented towards particle and theoretical
physics. She worked within the Swiss Space Center
to develop the concept of the HAGARE experiment as
well as on the avionics for the SHAGARE project.
2.3
Methodology
This work was conducted in two different laboratories. The two students from the Swiss Space Center
were involved in the engineering approach whereas
the LPHE was interested in the physics that can be
done at high altitudes as well as the detector and its
data acquisition.
As a first step, the two teams reviewed several past
experiment carried out on BEXUS and other systems
at high altitudes. Secondly, the science goals were determined by the LPHE while the SSC looked into the
constraints of the BEXUS program as well as smaller
balloons. Thirdly, in order to gain experience in treating with high altitude balloons systems, it was agreed
that a small meteorological balloon mounted with a
detector should be sent. From this point onwards, the
work of both teams concentrated on developing this
will from the point of view of the flight system of the
balloon, its ground support and the detector.
Meetings between the two laboratories were organised every other week at least to provide each other
with their latest developments and questions.
Thibault Kuntzer is a second year master student accomplishing his minor in Space Technologies after finishing the course from his major in physics oriented
towards astrophysics. He worked within the Swiss
Space Center to develop the concept of the HAGARE
experiment as well as on the avionics for the SHAGARE project.
page 6 of 67
Chapter
Issue 1
3
Fundamental of Astroparticles Physics
Astroparticles physics is a subbranch of particles ing energies in the center of mass of the system far
physics. It specializes in the study of elementary par- beyond what can be done with an accelerator on Earth.
ticles that originated from astrophysical phenomenon,
and is thus very close to astrophysics and cosmology.
The field of astrophysics describes the origin of astroparticles, whereas particle physics explains their
dynamics and interactions. The link between particle physics and astrophysics was discovered early on
but it is not until the discovery of the oscillation of
neutrinos that this branch developed.
Among neutrino physics, the study of gravitational
waves and dark matter, cosmic rays is one of its biggest
topic of research.
3.1
Cosmic rays :
overview
an historical
The cosmic rays were first detected by Victor Hess
in 1912, using a particle detector embedded on an
atmospheric balloon. Before 1912, it was believed that
all the radiation observed on Earth came from the
Earth itself (for instance from the radon accumulating
in underground caves). Hess showed that even if
radiation seemed to decrease with altitude, after
a certain altitude it increased again, hinting for a
extraterrestrial source of radiation, which he named
cosmic rays. A hundred years after their discovery,
the origin of cosmic rays is still unclear.
We distinguish primary cosmic rays from secondary
cosmic rays, which are primary rays that have interacted with the Earth’s atmosphere and can be detected
on the surface. Until the 1950s, most of the discoveries
in particles physics were done using experiments on
cosmic rays. Indeed their high energy allowed to
observe the positron, the muon, the charged pions
and a few strange particles. Starting from 1955 all
the new particles were detected with man-made
accelerators.
But even nowadays the particles
in cosmic rays presents the advantage of reachSwiss Space Center / LPHE
Figure 3.1: Spectrum of Cosmic rays – Credit [17]
Figure 3.1 represents the flux of cosmic rays depending on their energy. We can distinguish two changes in
the curve : the "knee" around 1015 eV and the "ankle"
around 1019 eV. The rays are best characterized until
the "knee" due to direct observation of the primary
rays in space or high atmosphere. These rays can genpage 7 of 67
erally be linked to cosmic events such as Supernovae
explosions. Around the "ankle" the fluxes are to low
to be detected directly by satellites or balloon but the
primary rays can be reconstructed from measures of
the secondary rays on Earth. For energies higher then
the "ankle", the particles are assumed to be created
and accelerated outside of our galaxy, maybe in AGN
(Active Galactic Nuclei) or GRB (Gamma Ray Burst).
3.2
Photons in cosmic rays
Issue 1
− Gamma Ray burst (GRB) are short bursts of soft
gamma-ray emission in the energy range 0.1-10
MeV which overlaps with the energy detection
of HAGARE. They last from ∼0.1 ms up to 100 s
originating from very different regions. The flux
of gamma-rays is such that it can perturb satellite operations. GRBs were discovered back in the
1960s and were mistaken for nuclear explosion
at the very beginning. GRBs could be linked to
supernova explosions however there is little evidence to support this.
Photons in cosmic rays (also called gamma rays) are Yet the exact origin of gamma rays is still incertain.
absorbed in our atmosphere, thus their study has al- The detection of photons in cosmic rays is done in two
ways been linked to satellites and high altitude bal- different ways depending on the energy :
loon. Their origins are multiple, but we can distin− For energies lower than 100 GeV, satellite or high
guish three main mechanism of their formation :
altitude ballon, as described in this report, are
appropriate. Indeed the fluxes at these energy is
Bermsstrahlung : A high energy particle, typically a
high enough to allow for small detection surfaces
electron, looses energy when deflected by a magand we can then observe directly the primary rays,
netic field. The kinetic energy lost is converted in
without noise from the atmosphere.
a photon.
Synchrotron radiation : When charged particle are
accelerated radially, they produce electromagnetic radiation.
− For energies higher than 100 GeV, detection on the
surface of the Earth has to be considered.
Inverse Compton scattering : In the Compton scattering, an inelastic collision between a photon and
a charged particle (typically an electron) transfers
a part of the photon’s energy to the charged particle. In the inverse phenomenon the charged particle exits the photon.
Thus gamma-rays are generally produced by interaction of cosmic rays with matter in the interstellar
medium. Other potential sources are events or objects
with a combination of high magnetic field and ejection
of high energy particles. The different possibilities are :
− Pulsars are pulsed sources in the sky with periods
in the range 1 ms to 10 s. They are often found
in the centre of supernova remnant shells which
naturally suggests that they are the result of core
collapse. The faster rotating pulsar indicate that
their density is extremely high much larger than
normal stars.
Figure 3.2: Artist view of a Gamma Ray Burst
Gamma rays are the most energetic particles that
we receive on Earth, their study allows to explore cos− Active Galactic Nuclei (AGN) are home to com- mological distance or high energies, and are used to
pact sources of gamma-ray emission. Having ex- explore the intergalactic medium.
tremely high luminosities (typically brighter than
the Milky Way), the brightest AGNs resemble
stars in the visible spectrum ! Those very bright
AGN are called quasi-stellar objects – quasars.
Their variability is an indication of their size
which can be estimated to about 1 AU ! The objects that powers such huge energy output are
assumed to be supermassive black holes.
page 8 of 67
Chapter
Issue 1
4
HAGARE Concept
4.1
The BEXUS concept
of sight of the antennae on the ground. These antennae can receive data up to a distance of 550 km at 30
The BEXUS program is developed for ESA by the km altitude. The EBASS system is also equipped with
German Aerospace Agency and the Swedish National an Air Traffic Control transponder.
Space Board. The campaign management and its opThe ballast mass provide altitude control as balerations is performed by EuroLaunch which is based last can be dropped to compensate a slight descent
at Esrange Space Center near Kiruna in Sweden. They of BEXUS at floating phase.
operate one balloon BEXUS (Balloon Experiment for
Below the ballast, are located GPS receiver as well
University Students) and one rocket REXUS (Rocket as an ARGOS receiver/transmitter to provide redunExperiment For University Students) nominally each dancy to the position determination provided through
year. The program started to fly regularly from 2004 the EBASS system and a radar reflector such that Air
[11]. All informations concerning BEXUS are retrieved Traffic Control can monitor the trajectory of BEXUS.
from the BEXUS User manual [3] unless stated otherFinally, there is the Gondola which is the payload
wise which shall be consulted for a more comprehenholder.
There are two different different gondola that
sive overview of BEXUS.
can be used : Esrange gondola (Egon) is a mediumsized gondola with dimensions of 1.5 × 1.5 × 1.0 m3 .
4.1.1 The BEXUS Flight system
It is designed to carry experiment loads up to 200 kg
and Small Egon (S-Egon) is small-sized gondola with
The complete system is composed of several different dimensions of 0.75 × 0.75 × 0.65 m3 . It is designed
subsystems that are described in the following para- to carry payloads up to 100 kg. However, there are
graphs from top to bottom. The complete length of several experiments on board (between 3 and 8) such
the system is 75 meters. The system is depicted on Fig. that BEXUS is not an experiment-dedicated program.
4.1.
The balloon is a Zodiac 12 SF plastic balloon envelope filled with 12,000 m3 of helium. It is designed to
float in near space until separation is commanded by 4.1.2 The Selection
Esrange.
Directly below the balloon itself is located the cutter The call for proposal is open between early September
which is used to cut the wire supporting the rest of the and end of October 20131 . The answer to this call is
flight system. It is activated by Esrange and can be a document summarizing the objectives of the experiused to terminate the flight in emergency situations.
ments and its realisation (See appendix §A) and posted
There is then the parachute that slows the flight sys- to the ESA Education Projects database.
tem in its fall to the ground. The parachute is already
Proposals will be assessed by a panel of experts and
open during the ascent such that its deployment is
pre-selected experiments will be announced. Those
passive.
teams will be invited to participate in selection workThe EBASS system is the tele-command and telemeshops where a final selection will be made.
try system of BEXUS. It provides Esrange with housekeeping informations as well as the position of the
1 This is extrapolated from the call in 2012, the actual dates are
balloon. It is actually this subsystems that usually
constrains the flight duration as it must be in the line not known and should be checked on [11]
page 9 of 67
Issue 1
Figure 4.2: Flight trajectory of Bexus 11.
4.1.4.1
Launch Conditions
BEXUS is launched in September or October which
implies that as Esrange si in the North of Sweden, the
duration of Sun light is fairly short. Even though the
count down lasts for only 3h30, the launch windows
opens as early as 5 am and closes at 8 pm LT. The major
constraint is the weather condition and particularly the
ground wind speed which should be less then 4 m/s
horizontally and the visibility which should be larger
than the BEXUS total height of 75 m.
4.1.4.2
Ascent Phase
After the launch, the balloon will ascent at a typical
5 m/s vertical velocity during approximately 2 hours.
The flight dynamic is usually smooth with a initial
ground drift velocity of 5-10 m/s, however Gondola
might
oscillate slightly or spin. Moreover, shocks
Figure 4.1: The BEXUS flight trains and the different elemight
sometimes
happen with the Hercules launch
ments : balloon, cutter, telemetry, housekeeping and payload
vehicle,
in
the
first
few minutes of the flight.
holder
4.1.4.3
4.1.3
The Pre-Flight
Once the teams arrived in Kiruna, the flight campaign
begins and lasts about a week. The main activities
are the integrations of the instruments on the Gondola
as well as heavy testing notably the electromagnetic
interferences tests.
4.1.4
The Flight
On Fig. 4.2, the trajectory of BEXUS 11 is represented. This flight embarked the PERDaix experiment
in which the EPFL was involved (see §4.3) it flew 450
kilometers to Finland and lasted 3 hours 20 minutes
[12]. In the following paragraphs, the different phases
of the flight are briefly described.
Float Phase
Once the nominal altitude of 20–35 km, which depends
on the total payload mass as well as weather conditions
and can be predicted right before the flight by the
Esrange staff, is reached BEXUS is in the float phase
which means that the buoyancy of the balloon balances
the weight of the payload. This altitude does not vary
by more than 200 m during this phase. The duration of
this phase is between 1 and 4 hours. Gondola will still
spin at this altitude. On the ground, the teams monitor
and control their experiment through a tele-command
& telemetry link called E-link.
4.1.4.4
Descent Phase
Upon the termination of flight command issued by
Esrange, the cutter will free the balloon from the rest
of the train which starts to fall back to the ground. The
page 10 of 67
parachute slows down the descent to an approximate
8 m/s.
4.1.4.5
Landing
The launch of BEXUS is authorized if the predicted
trajectory will imply a landing in a sparsely populated
area. The precise timing of the termination command
ensures this condition as well. However, the terrain
onto which the payload will touch down is unknown
and can a priori be an hostile environment for electrical or mechanical components. As Gondola possesses
shock-absorbing legs, no damage is usually caused to
the experiments.
Issue 1
− Rare shocks with Hercules launch vehicle
− Submersion in water, during landing soil/organic
material may become lodged
4.2.2
Thermal Requirements
− Overall temperature range : −90 – +30°C
− Indoor Esrange facilities temp. : 20 ± 5°C
− Outdoor Esrange facilities temp. : −15 – ∼ 0°C
4.1.5
The Recovery
The payload will be recovered by a helicopter and then
transported to a truck for the return trip to Esrange
within 24–48 hours.
− Flight temperature range : −90 – ∼ 0°C
− Post flight & pre recovery temp. : −15 – ∼ 0°C
4.1.6
Post-Flight Activities
Before the end of the flight campaign, each team is 4.2.3 Electrical Requirements
required to present the performance of their experiment. A report must also be issued to discuss the final Power Requirements
results.
− Experiment is to be turned on/off several times
4.2
BEXUS Requirements
In the BEXUS user manual [3], the whole launch campaign is described in detail. From this document, we
extracted the different requirements with which a selected experiment must comply. In the user manual,
the necessary tests are described as well as the different
constraints on the frequency usage. It must be pointed
out at this point that the BEXUS team is going to conducts electromagnetic tests before the launch. Failing
to comply with the reserved frequencies policy will
prevent the experiment from flying or will fly without
power.
4.2.1
Mechanical Requirements
− Mass: total mass up to 100 or 200 kg (in total for
all the different experiments)
− Pressure range: 0.5 – 1100 mbar
− Gas-tight or equipped with venting holes
− Accelerations: -10 g vertically, ±5 g horizontally
− Resistant to a drop from 3 meters
− Withstand loads of 10-30× its mass
− Fixation by rails separated by 360 mm
− Phase consumption duration:
· 6h Pre Flight tests
· 6h Count down / launch attempts
· 6h Flight
· 24h post flight waiting time till recovery
− Total time : about 42 hours
Provided Electrical System
− 28V / 1A, 13 Ah battery power source
− Location : outside the experiment
− Connector : 4 pin, male, box mount receptacle
MIL – C-26482P series 1 with an 8-4 insert arrangement (MS3112E8-4P)
− Pin A is +, pin B is − and shall not be connected
to chassis or GND
Other Electrical System
Another system can be selected, however the choice
shall be discuss with BEXUS project manager before
critical design review.
page 11 of 67
Issue 1
A recovery plan document shall be produced in order for Esrange staff to recover the experiment quickly
without danger.
Radio-frequencies transmissions and allocation permissions shall be given by Esrange and PTS (Swedish
Post and Telecom agency).
Hazardous items may need further investigation by
Esrange Safety Board.
A list of hazardous materials shall be established
and be compliant with the Swedish Work Environment
Act.
A post flight presentation shall be given on the performances of the experiment.
An outreach program shall be put into place. Its
precise form is not defined, from past mission we can
deduce that it can take the form of a website with
talks open to the public in the home local media or at
University.
4.3
REXUS/BEXUS – EPFL Heritage
Figure 4.3: The E-Bass (TOP) and E-link (BOTTOM)
telemetry and tele-command for respectively housekeeping
This mission is a heritage from two other missions deof BEXUS and experiment data.
sign by the EPFL using the BEXUS/REXUS program.
The first project (PERDaix) used a BEXUS balloon,
while the second GGES a REXUS rocket. Both were
4.2.4 Telemetry and Tele-command
launched successfully and developed a collaboration
EBASS shall only be used by Esrange which provides between universities or laboratories.
flight control (Altitude, GPS, termination, housekeep4.3.1 PERDaix
ing)
The following frequencies shall not be interfered :
PERDaix (Proton Electron Radiation Detector Aix-la400-405 MHz, 449-451 MHz, 1025-1035 MHz, 1089Chapelle) is a particle detector launched on BEXUS on
1091 MHz and Ch 2-14 in 2.4 GHz-band.
the 23rd of November 2010. The aim is to study the
E-Link for data transfer to and from GND
cosmic rays and thus the idea of flying the experiment
− Interface : Ethernet 10/1000 Base-T Protocol and 3 on a high altitude balloon to minimize the impact of
the atmosphere, was proposed. The project is a colasynchronous duplex RS-232/422 channels
laboration between the RWTH Aachen University and
the LPHE of EPFL.
− Data bandwidth: 2 Mbps duplex nominal
Just as for HAGARE, the science involved in PERDaix is astroparticle physics. The detector can detect
− Connector: MIL-C-26482-MS3116F-12-10P
particles with energies between 0.5 GeV and 5 GeV
− Serial communication with RS-232 shall not be and identify helium, protons, electrons and positrons.
used
The goal is the develop a better understanding of the
composition of charged cosmic rays, by for instance
measuring the ration of positrons to electrons.
4.2.4.1 Administrative Requirements
As the objective of PERDaix is to detect and identify
A comprehensive Student Experimental Documenta- different particles, multiple detector are used : a timetion (SED) shall be submitted for the Preliminary De- of-flight detector, a charged-particle tracking detector
sign, Critical Design, Experiment Building and testing, and a radiation detector. The tracking detector deFinal Experiment preparations, Data Analysis and re- mands a 0.2T permanent magnet that is a big driver of
porting. This document shall allow Esrange staff to the final mass of the experiment. Moreover a permaoperate the experiment in case weather postpones the nent magnet also has repercussions on the electronlaunch after the expected end of the campaign and the ics and thus on the electrical design. This is one of
return of the team to their home universities.
the main difference between PERDaix and HAGARE
page 12 of 67
from the engineering point of view. As we will see
later HAGARE only has one kind of detector and no
magnet. One might think it is a small detail but a
permanent magnet induces complication for the other
instruments and electronics.
As PERDaix is a important source of inspiration for
HAGARE we will described briefly the different subsystems.
Issue 1
4.3.1.2
Electronics
The Data Processing Unit (DPU) reads out the detector
and processes the data before storage on the Data
Storage Unit (DSU). The compressed data can then
be downloaded using the E-link. The DSU contains
the main software and can accept command from the
ground station. One of the requirements for the DPU
is that it shall allow for an average data throughput of
at least 8MB/s.
The DSU contains two solid state hard drives of
128 GB, used in redundancy. The maximum read
and write speed allowed is 90 MB/s but during the
experiment an average of 2 x 3.3 MB/s is expected.
The Analog-to-digital Unit (A/D) is composed of 3
USB readout boards, that are connected to the DPU
with USB cables. There is also a 12 bits converter with
a sampling frequency set to 1MHz but that can go up
to 5MHz.
The Slow Control Unit (SCU) is used for all the
housekeeping.
A/D boards are used to convert
voltages in digital signal and read out the temperature
and pressure sensors. The data is compressed using a
zero suppression algorithm.
Events are send to ESRANGE via the E-link : 200
bytes at 300Hz giving a data rate of 58KB/s.
4.3.1.3
Power Supply Unit
The PSU contains a battery pack and converters to
achieve the required voltages.
The battery pack is composed of battery units connected in parallel. Each units contains 8 D-cells connected in series. The cells weigh 92 g and provide 13
Ah at 3.6 V, giving a energy density of 450Wh/kg. The
4.3.1.1 Science payload
design can hold 5 units but with 4 units the experiment
The science payload is composed of 3 different detec- can be operational for 12 hours at 80 W. As at low temtors that combined allow to detect, identify and mea- perature the capacity of the batteries decreases, some
sure the energy of charged particles.
insulation is needed.
Figure 4.4: PERDaix subsystems – Credit [5]
− Time-of-Flight (TOF) : Charged particle detector
plates, placed on top and bottom of the whole 4.3.1.4 Thermal design
design. If a charged particle passes through it, it
is detected and the time of flight can be computed. During testing the coldest and hottest components
have been identified. Even if the temperature reached
− TRACKER : Placed around the magnet, this de- are inside the operational limits, the performance
tector tracks the trajectory of charged particles.
would be optimal with thermal isolation. Therefore
and in order to achieve a more homogenous temper− Transition Radiation Detector (TRD) : allow ature, some isolation was added, using 10mm stryto distinguish between electrons, positrons and rofoam panels, that add approximatively 1kg to the
heavier particle of the same charge.
weight.
page 13 of 67
Issue 1
particles were recorded. The flight was nearly a full
success, all the data taken was secured. The detector
survived the landing and is still fully operational. But
there were a few hardware issues : corona discharges,
loose fiber ribbons and the performance of the thermal
design were not as good as expected. This should be
kept in mind for the design of HAGARE and more
specifics on the problems could be asked to PERDaix
team.
Figure 4.5: Power distribution is PERDaix – Credit [5]
4.3.1.5
Structure
The structure of PERDaix is made out of a simple case
of carbon fiber with aluminum honeycomb core. The
two side panels (400mm x 859 mm) carry the magnet,
whereas the two support panels (246 mm x 859 mm)
carry the TRACKER and the TRD. Bottom and top of
the case are closed with 560 mm x 575 mm panels. The
bottom plate contains a system to fix the experiment
to the gondola.
4.3.1.6
Experimental modes
The experiment can be set in different modes depending
− Power Off : all components are off, at the event
Power On the experiment goes to the mode Initialized.
− Initialized : Except for high voltage everything is
turned on.
− Calibrating : The high voltage en sensitive detectors as the TRACKER, the time-of-flight detector
and the radiation detector are calibrated.
Figure 4.6: PERDaix experiment – Credit [5]
4.3.2
GGES
− Reading Out : the experiment waits for charged
A second experiment, this time using the REXUS proparticles, reads out the different detector and store
gram was launched on the 22nd of March 2012. The
the data on the DSU.
GGES (Gravity Gradient Earth Sensor) was a collabo− Error : high voltage is turned off and the experi- ration between the Swiss Space Center and the LMTS
(Microsystems for Space Technologies Laboratory) at
ment tries to identify the error.
EPFL. The aim was to test a new Earth sensor develThe final design weighs 40kg and uses 60W of oped by EPFL, that uses the gravity gradient induced
electric power.
by the Earth. The REXUS rocket goes up to 80km and
The experiment was successfully launched on 23 of then free-falls back to Earth. During this fall the experNovember 2010 as part of BEXUS-11 and recovered iment undergo micro-gravity, and this is well suited
after almost 3.5 hour flight, covering a distance of 450 for a gravity-gradient experiment. Figure 4.7 shows
km. During the float phase more than 170’000 charged the experimental principle. The data recovered is still
page 14 of 67
Issue 1
being processed.
Figure 4.8: The figure on the left hand side illustrates the
general configuration of the detector. The figure on the right
hand side shows one single gamma-ray solid state detector.
Figure 4.7: GGES experiment principle – Credit [13]
4.4
General description of the detector
This short section summarises the operating principle
of the gamma-ray detector that will probably be used
for the HAGARE high-altitude gamma-ray detector
project. The precise design of the detector is still under
studies and is therefore not exactly known yet. Hence,
the description presented hereafter is subject to further
improvements.
The present design of the detector consists in the
setup shown on figure 4.8. It is basically a hemispherical structure on top of which approximately
twenty gamma-ray detectors, each of which consisting
in a crystal scintillator and a silicon photo-multiplier
(SiPM), described below. The gamma-ray detectors
are separated from each other by a lead shielding, in
order to give some clue about the directional origin of
the incoming rays. Each detector is also covered by a
foil, hence preventing daylight to trigger the SiPMs.
A larger crystal will possibly be placed in the middle
of the hemispherical structure but this possibility has
not been precisely investigated yet.
The purpose of the following sections is to briefly describe the physical phenomena which allow gammaray detection.
− Firstly, the gamma photon can be photoelectrically absorbed by an orbital electron. This electron
acquires a kinetic energy Ek = ~ω − Eb where Eb is
the electron binding energy and ω is the pulsation
of the photon. This case is the most interesting
because the full energy of the gamma is absorbed
by the electron.
− The second way is Compton scattering, where the
photon elastically scatters an electron. In this case,
the kinetic energy of the recoil electron strongly
depends on the scattering angle. It can easily be
proven that the kinetic energy of the recoil electron lies between 0 and a maximal value which is
always strictly lower than the full energy of the
photon.
− Lastly, if ~ω ≤ 2me c2 where me is the electron
mass, the photon travelling in the vicinity of an
atomic nucleus can produce an electron and an
anti-electron pair, the energy of each of which is
given by Ee = 21 ~ω − me c2 .
In these processes, the excited electrons can disperse
their energy in various different ways, e.g. thermally
or by emitting lower energy photons. The last possibility is the most interesting for gamma detection.
This scintillation process can occur in various ways
depending on the crystal used. In the case of bismuth
germanium oxide (BGO), whose performances have
been measured, the electron disperses its energy by
interacting with bismuth ions, which relax emitting
photons [4] in the visible spectrum. In the case of another crystal which has been studied, thallium doped
sodium iodide (NaI(Tl)), the de-excitation process oc4.4.1 Gamma-Ray Detector
curs in a the vicinity of a thallium impurity, where the
energy levels are closer to each other, also emitting
4.4.1.1 Crystal Scintillator
visible photons [2].
In the detector investigated here, gamma-rays first
Once scintillation photons are emitted, they reflect
scintillate in an inorganic crystal by interacting with on the crystal coating (typically made of teflon, see
an electron. In the range of energies being probed in figure 4.8) before being converted into an electrical
this project (approximately 50 − 2000 keV), gamma- current in an SiPM, whose operating principle in derays mostly interact through three distinct ways [2]:
scribed in the following section.
page 15 of 67
Issue 1
Figure 4.10: Pulse spectrum observed with a BGO crystal
coupled to an SiPM.
4.4.2
Figure 4.9: This figure depicts an avalanche photodiode.
The n+ and p+ layers respectively represent the regions
which are highly doped in donors or acceptors. An incoming
photon will excite an electron-hole pair in the middle depletion region. The electron then drifts to the p and n+ layers
where the electric field is so high that the electron generates
an avalanche of new electron-hole pairs.
4.4.1.2
Silicon Photomultiplier
A silicon photomultiplier is a device designed to count
a number of photons. It is made of an array of
avalanche photodiodes, connected in series with a resistor. An avalanche photodiode operates in Geiger
mode, that is to say that the bias voltage applied to the
diode is higher than the breakdown voltage, which
means that any photon entering the diode produces
a breakdown current which is stopped only when the
voltage drop in the resistor will be sufficiently large
[6]. Such a diode is sketched on figure 4.9. Hence, an
avalanche photodiode gives a signal which is independent on the energy of the incoming photon. Therefore,
when submitted to a flash a photons, an SiPM gives
a currant pulse which is proportional to the number
of incoming photons [7]. One of the advantages of
this device is that the avalanche mechanism acts like a
current amplifier.
Measurements and Further Investigations
Several detectors have been tested using two radioactive sources: 137 Cs emitting a 0.66-MeV photon and
60
Co emitting a 1.17-MeV and a 1.33-MeV photon. Figure 4.10 shows a spectrum obtained using a BGO crystal. The x axis is the pulse area, which is supposed to
be proportional to the energy of the detected gamma
photon. This spectrum clearly shows, for both caesium and cobalt sources, a peak on the left hand side
which corresponds to backscattered gamma-rays, i.e.
photons having been Compton-scattered in the detector environment. Then, a plateau can be observed
(predominatingly for the cobalt spectrum) which is
due to the photons which where Compton-scattered
inside the crystal. Finally, the photoelectric peaks can
be seen on the right hand side of the spectra. Notice
that the low resolution of the device does not allow for
a distinction between the two cobalt emission peaks.
Considering all this, the following characteristics
can be taken into account when choosing a suitable
detector for the experiment:
− The resolution must be good, i.e the photoelectric
peak must be as thin as possible.
− The proportion of photons interacting photoelectrically must be maximal.
− The efficiency of the detector, i.e the proportion
of photons reaching the detector that are actually
detected, must also be taken into account.
− The behaviour of the detector as a function of the
temperature must be well known or controlled.
Photodiodes are particularly sensitive to temperature variations.
For the measurements undertaken so far, the SiPM
model was the Hamamatsu MPPC S10985 - 050C consisting in an array of 140 400 avalanche diodes. The
The main purpose of the high energy physics group
bias voltage is 71.5 V, corresponding to a power con- taking part in the HAGARE project for the next months
is to design and precisely characterise such a detector,
sumption of approximately 4 mW.
page 16 of 67
Issue 1
which will allow for its implementation in the bal- be detected afterwards) and therefore the solid angle
loon’s gondola.
per scintillator is :
4.5
θ∼
Technological Development
2π(1 − cos 20°)
≈ 0.22°
100
(4.1)
Therefore the attitude determination shall be at least
better than 0.22° at all time during the flight.
The read-out of this detector is a trigger which
− Scientific Payload;
means that a threshold must be set to filter out the
noise. A trigger also implies that there is not a contin− Attitude and Altitude Determination;
uous flow of data, but it is event-driven. One event is
characterized by 8 or 10 bits.
− Thermal Control;
A trade-off should be established to decide whether
to
switch the scientific payload on before or in the flight
− Command & Data Handling.
depending on its power consumption and difficulty to
In this section, the subsystems are described and their start-up.
performances as well as their relationship with one
another are characterised. The block diagram of the 4.5.2 Attitude and Altitude Determination
engineering part is shown in Fig. 4.11. The scientific
(AAD)
payload will not be detailed in much depth as it the
subject of investigation of the LPHE.
4.5.2.1 Attitude Determination
HAGARE is composed of several subsystems :
E-Link
Detector
2 Mbps
Ethernet 10/100 Base
...
N
1 2 3 4 5
Trigger
Event-driven
On/Off
1/30 Hz
Attitude Determination
Magnetometer
Σ
5 Hz
Housekeeping
T1
V
T2
A1
Σ
Central
Processing
Unit
1/30 Hz
2 Hz
...
...
TK
Thermal
Accelerometer
AM
min. 1 Hz
Altitude Determination
GNSS Decoder
Mass
Storage
Unit
Figure 4.11: HAGARE Block Diagram with sampling frequencies for the subsystems.
4.5.1
As discussed before, a given attitude precision is required to be able to deduce the origin of a gamma-ray
in the sky. The spin of BEXUS is not determined a
priori, but can be deduced to one or two rotations per
second. Therefore a determination with 5 Hz is needed
at least.
The magnetometer that determines the angle with
the magnetic field of the Earth is biased when it is
inclined with respect to the zenith. To compensate
this effect, accelerometers must be used. The system
should be redundant and placed at different physical
location in HAGARE to mitigate eventual effects of
external magnetic fields of other experiments.
4.5.2.2
Altitude Determination
The altitude is a very important measurement if the
detector is switched on after the launch. In all cases,
it will help determine the kind of events. The altitude
sensor is composed of a GPS receiver. BEXUS possesses already a GPS receiver, but its reading may not
be used by any experiment. As the ascent and descent
rate are maximum 10 m/s and that the approximate
vertical precision is 5 meters, a sampling frequency of
2 Hz is enough.
Scientific Payload
The number of channels for the scientific payload is yet
to be determined, however the latest figure discussed
with the LPHE was of maximum 100. A channel is one
scintillator with a certain position and inclination on
the dome. The angular resolution for 100 channels can
be computed. The angle made between the zenith and
the last scintillator is about 20 degrees (no event can
4.5.3
Thermal Control
The thermal control is responsible to maintain the temperature within operational range in the experience.
This is done via a passive design as well as active
heaters. The sensibility of the detector will vary with
the temperature. Thermometers must be placed in several locations and feed at a very low frequency (one
page 17 of 67
measurement every 30 seconds) the central processing
unit which will actuate the heaters. The thermal control should not be neglected in the design process. On
PERDaix, it was its major flaw.
4.5.4
Command & Data Handling (C&DH)
4.5.4.1
Central Processing Unit (CPU)
The central processing unit is able is process all the
inputs from the housekeeping (voltage, current, temperature), AAD data as well as the scientific data. All
of those subsystems have different data rate and sampling frequency. A high computing power is not required as no processing of the data will be done except
for the magnetometer tilt corrections which are linear
equations. The purpose of the central processing unit
is to packetize the data and store, send data via the 2
Mbps Ethernet bus to E-link, manage the power and
manage the heaters.
The communication to E-link should include telemetry and data. The software should be able to understand commands from the ground as well. This is a
BEXUS requirement.
Issue 1
As the project is to fly with BEXUS, there are some constraint on the time scale, once the project is accepted.
The call for proposals is opened each year in the beginning of September and closed end October. Following
the acceptance of the project, the schedule goes as :
− Begin December : Selection Workshop at DRL
Bohn or at ESA-ESTEC.
− Begin February : Student Training Week and Preliminary Design Review at DLR Oberpfaffenhofen
− May : BEXUS Critical Design Review (CDR) at
ESA-ESTEC
− June : BEXUS Integration Progress Review (IPR)
at the university (in this case EPFL)
− August/September : BEXUS Experiment Acceptance Review (EAR) at the university
− September/October BEXUS Campaign at SSC ESRANGE
− June of the following year : Experiment Results
Symposium
This is summarised in figure 4.1, for selection until
2015. Keeping this in mind, figure 4.2 proposes a
planning for the different phases of the project. As the
The mass storage unit shall be able to host at least
BEXUS selection is done once a year, we could keep
100 GB of information. The data write rate is not deapproximatively the same planning for the selection
fined yet, but was estimated at 4 MB/s for PERDaix.
in 2014.
In first approximation, this value should decrease dramatically as here the data flow is event driven and
gamma-rays are more rare to detect than charged par- 4.6.1 Assembly, Integration and Testing
(AIT)
ticles (see chapter 3). The hardware shall be such that
it can withstand shocks and very low temperatures.
The AIT is generally done in phase C. We propose here
Ideally, it should be air tight.
a few test that will have to be done. The list is clearly
not exhaustive and will have to be completed.
4.5.4.2
Data Storage Unit (DSU)
4.5.5
Electrical Power Subsystem (EPS)
4.6.1.1 Thermal and pressure tests
The EPS supplies the power to the different subsystems. Batteries with enough capacity shall be used to The environment of the flight is in near space, thus the
power the system for at least 12 hours. Three different design has to survive the harsh thermal condition and
buses are used : 3.3VDC, 5VDC and a dedicated bus as well as near vacuum.
for the instrument as it will require higher voltage to
T1
ID
run. The EPS is controlled via the CPU such that it can
Facility
needed
Thermovaccum setup
switch on or off the power. In case of major failure,
Item
tested
The whole experiment
it should also be able to cut high voltages or power if
Test
procedure
Simulate the whole flight : drive
applicable.
ambient temperature cycle between -40 °C and 0°C and ambient pressure down to 1mbar.
4.6 End-to-End Mission Summary
We will described here how the HAGARE mission
Especially the DSU containing all the data should
should proceed. Of course the duration exposed here
depend greatly on how many student will continue survive the flight or the mission will be a total failure.
Thus it must tested for harsher conditions then the rest
this project next semester and the following years.
page 18 of 67
BEXUS 12/13
REXUS 11/12
BEXUS 14/15
REXUS 13/14
BEXUS 16/17
REXUS 15/16
BEXUS 18/19
REXUS 17/18
BEXUS 20/21
REXUS 19/20
BEXUS 22/23
REXUS 21/22
Final Student Report RX
30.06.12
Outreach Programme
Final Student Report BX
15.01.13
Launch Campaign
RX 13/14
03.12
Selection of Experiments
Training Week
04.-08.02.13
30.06.13
Outreach Programme
Launch Campaign
BX 16/17
15.01.1!
Launch Campaign
RX 15/16
Selection
of Experiments
Training
Week
30.06.14
Outreach Programme
Launch Campaign
BX 18/19
15.01.1#
Launch Campaign
RX 17/18
Training
Week
Selection
of Experiments
Selection
Workshops
30.06.15
Outreach Programme
30.06.16
Outreach Programme
Launch Campaign
RX 15/16
Training
Week
Selection
of Experiments
Selection
Workshops
Launch Campaign
BX 16/17
Deadline for Proposals
Call for
Proposals
01.09.15
15.01.1"
2011
2012
2013
2014
2015
2016
Jun Jul Aug Sep Okt Nov Dez Jan Feb Mrz Apr Mai Jun Jul Aug Sep Okt Nov Dez Jan Feb Mrz Apr Mai Jun Jul Aug Sep Okt Nov Dez Jan Feb Mrz Apr Mai Jun Jul Aug Sep Okt Nov Dez Jan Feb Mrz Apr Mai Jun Jul Aug Sep Okt Nov Dez Jan Feb Mrz Apr Mai Jun Jul
15.01.12
Launch Campaign
RX 11/12
03.12
Training Week
06.-10.02.12
Selection of Experiments
Outreach Programme
Launch Campaign
BX 12/13
21.09.-01.10.11
23.10.11
Call for
Proposals
01.09.11
Selection Workshops
05.-08.12.11
Launch Campaign
BX 14/15
20.-30.09.12
Selection Workshops
10.-13.12.12
22.10.12
Call for
Proposals
03.09.12
Call for
Proposals
02.09.13
Selection
Workshops
Call for
Proposals
01.09.14
Table 4.1: REXUS/BEXUS program until 2015.
page 19 of 67
Issue 1
Issue 1
Table 4.2: Planning for the HAGARE project.
page 20 of 67
of the experiment. In test T2 we see put the surviving
limit to the test : can we still extract information of the
DSU. Whereas the test T3 focuses on the operational
limit : what are the performances of the DSU under
the gradient of temperature expected during the flight
and recovery of the payload.
ID
Facility needed
Item tested
Test procedure
T2
Freezer
DSU
Write some data on the DSU, put
it in a freezer at -60°C for a week
and check performance.
ID
Facility needed
Item tested
Test procedure
T3
Thermovaccum setup
DSU
Cycle the DSU in thermovaccum
(20°C to -40°C) at 1hPa and check
performance.
4.6.1.2
Mechanical tests
It is of outmost importance that the experiment survives the flight and landing. For this to be sure we
must test the experiment under low frequency vibration as we expect the gondola to vibrate slightly during the flight. The landing is somewhat more violent
which explains test T5. Just as before the DSU should
be tested in condition that could seem excessive (test
T6), to make sure it survives the worst landing possible.
ID
Facility needed
Item tested
Test procedure
T4
Vibration table
Low frequency vibration test of
the experiment
ID
Facility needed
Item tested
Test procedure
T5
Drop the whole setup from 3m to
check if it will survive the landing of the gondola.
Issue 1
ID
Facility needed
Item tested
Test procedure
4.6.2
T6
DSU
Write some data on DSU, put
into 1m of water for a hour and
check performance.
Flight Campaign
The launch will be at the Esrange Space Center in
Kiruna in the North of Sweden. PERDaix was taken
to Esrange by car by two of the team’s members. For
HAGARE it will have to be decided either to go the
3175 km to Kiruna by car, or to do part of the journey
by plane. Generally the team that goes to the launch
is composed of 10 to 15 members that have a good
knowledge of the experiment.
Once at Esrange HAGARE will have to undergo the
electromagnetic interference tests, to make sure that
non of the experiment on the gondola interfere with the
others. The launch decision depends on the weather
conditions and is taken by the staff of Esrange. It could
happens that the flight is denied and postponed for a
few weeks as it did for PERDaix. The different phases
of the flight have already been described earlier in this
report.
Once the gondola has safely landed it is recovered
by helicopter and truck and brought back to Esrange.
There the data is retrieved and the health of the experiment investigated, and the damage analyzed.
The experiment will have to be transported back to
EPFL to be stored. Finally reports on the analyzed
data as well as the an outreach program should be
set in place. We will also want to write a document
resuming the mission and the lessons learned. These
documents could serve a base for eventual follow up
missions.
page 21 of 67
Chapter
Issue 1
5
SHAGARE – Meteorological Balloon Sized
Experiment
5.1
Motivation and Requirements
From these constraints we define the following requirements. They flow down from the requirements
Following discussions with the Laboratoire de of HAGARE.
Physique des Hautes Energies (LPHE) and with the
Req-1 – Localisation The payload shall be located reSpace Centre in order to develop an experiment that
liably at all altitudes throughout the flight.
would fly on the high altitude balloon ESA program
for students (BEXUS), the idea of flying a much Req-2 – Orientation When the detector is operational
smaller payload on a smaller balloon popped up. For
the orientation of the balloon shall be known with
the PERDaix experiment most of space engineering
a precision better then 2.2 degrees.
part of the project was done by RWTH Aachen
University, whereas the EPFL focused on the science Req-3 – Temperature determination When the detector is operational, the temperature near it shall
and physics part. In order to gain some experience,
be measured and stored with time stamps.
the idea of design a smaller version of the project was
proposed. The second project is called SHAGARE
Req-4 – Housekeeping sensors The temperature and
(Small HAGARE).
pressure shall be measured at least at two different
The goal was to fly only a small fraction of the detector,
points in the payload, throughout the flight.
or to simulate the detectors presence by an other
object, with reduced avionics but based on the same Req-5 – Data Handling The test flight shall emulate
principle. One could even think about launching
the data handling process of the final mission.
multiple balloons to characterize more precisely the
temperature and pressure environment, or to verify Req-6 – Temperature range The temperature onboard shall be at all time in a range for the
that the avionics fulfill the different requirements.
electronics to operate.
Indeed two very specific requirements came from the
LPHE : the detector is temperature sensitive and thus
the temperature in the payload structure has to be Req-7 – Temperature control When the detector is
operational, the temperature near it shall be stable
known at all time and if possible a thermal system
at ±5°C.
should be design to keep the temperature near the
detector as stable as possible. Secondly the position Req-8 – Software Size The SHAGARE software shall
and orientation of the detector should be known at all
hold on 32,256 byte maximum
times during the flight. Indeed for the processing of
the data, knowing if the detector is pointing at the Sun In the following we will see how these requirements
or at empty space, is important. Thus, to reconstruct are met.
the data correctly, the orientation of the detector with
After looking at possible balloon (meteorological
respect to the flight path is needed.
balloon) and taking the different constraints and
Another constraint on the design comes from the requirements in consideration, two possibilities
Swiss law (Art 16, VKL) small stratospheric balloon emerged.
These small meteorological balloons,
can only have payloads up to 2’000 grammes.
depending on the weight of the payload, can go
up to 35 km. But off-the-shelf balloons are closed
page 22 of 67
and as the gas expands with the increasing height,
they explode once the envelope is stretched by the
helium to its structural limit, beginning their descent
immediately when they reached the desired altitude.
It is possible to modify these balloon, opening their
lower end to have them float a little while at 35 km
before descending. This of course induces a certain
cost. These options are summarized in table 5.1.
The trade-off is between cost and preparation time
versus data volume and interest of the mission. As
the Float Around option would take a long time to be
manufactured, and as the main goal of SHAGARE is
not to collect science data but to validate the design
for HAGARE, it was decided to go with the Lift and
Fall option.
Issue 1
(according to Swiss laws Art 16, VLK) payloads up to
2’000 grammes. The purpose of this work is to discuss the open source Trackuino board which provides
a low cost solution for high altitude balloons tracking
based on the popular Arduino board and the Automatic Packet Reporting System (APRS) to report the
trajectory on the web thanks to radio amateurs frequencies.
Float Around
Lift and Fall
Reaches 35 km in altitude
Begins descend
Float phase for
some time
immediatly
Expensive
Cheap
Long engineering,
Available
manufacturing time
off-the-shelf
Figure 5.1: A Trackuino board – Credit [15]
Table 5.1: Characteristics of the two option for SHAGARE
5.3.1
5.2
Science Instrument
Initially the goal was to fly a small part of the detector intended for HAGARE on SHAGARE but finally
an off-the-shelf was bought. The detector – C12137 –
is built by Hamamatsu in Japan and is a state of the
art gamma-rays detector which came on the market in
mid 2012. It weighs 117 g and uses 750 mW.
The drivers to readout this detector only function on
Windows. To accommodate this, the decision was
made to have two OBC, one managing the avionics,
reading out the housekeeping sensors and storing the
housekeeping data whereas the other focuses on reading out the science data. Either the science OBC stores
the science data or we can connect it to the housekeeping OBC for data storage.
As the detector is pretty expensive, the requirement
to localise and retrieve the payload increased.
5.3
Avionics and Hardware
This report focuses on the functional and the hardware
description for a housekeeping and telemetry system
for stratospheric small balloons class that would lift
Trackuino Capabilities Analysis
The Trackuino project was developed to ensure tracking of small high altitude balloons for licensed radio
amateurs. It features a GPS chip, 2 temperature sensors, a “buzzer” used for post flight quick recovery
and a VHF radio-transmitter. This open source project
distributes schematics and board layouts for the standard design. In the following, we discuss how the
Trackuino must be adapted to meet the requirements.
Trackuino is designed to run on a Arduino UNO
board which provides six analogue I/O pins, fourteen
digital I/O pins and operates on a 5VDC voltage. The
board does not have built-in data storage capabilities
nor does it provide orientation. Those capabilities
must be implemented in the Trackuino board1 as well
as a pressure sensors that is not built-in.
The requirement Req-1 demands that the localisation of the payload shall be efficient and reliable.
Trackuino does offer a positioning chip of which the
data is relayed down to the ground via the VHF transmitter. The chip is the “Venus638FLPx GPS Receiver”
which receives GPS signal only on the L1 frequency.
According to its data sheet, the operational limits are
that the chip can work by exceeding either one of the
two following limits : altitude < 18’000 m or velocity
< 515 m/s, but not both. The limit on the altitude will
1 or
“shield” as it comes on top of an Arduino board
page 23 of 67
not be respected hence the velocity of the balloon shall
be at all time below 515 m/s which is 1854 km/h and
therefore not an issue.
This system has one constraint : a receiving antenna
must be in the line of sight of the balloon at all time.
This may not be the case as the balloon may travel far
and speed greater than what the recovery team can
achieve. The connexion may be severed at some point
during the flight. This demands for a more reliable
and more robust back-up option.
The requirement Req-3 expresses the need to probe
the payload environment as the detector provided by
the LPHE is temperature sensitive. Two temperature
sensors are already built in the Trackuino hardware :
one measures internal temperature of the board while
another one can be attached to measure temperature
outside the payload. To meet our requirements this is
changed to two external temperature sensors, instead
of one internal and one external. The idea to exchange
an internal sensor for an external one, is to be able to
place it were it is needed in the payload, for instance
near the detector. Those LM60 one wire thermometers
require one analogue pin on the Arduino board. The
pressure sensor would also require one analogue pin
while the compass require two as it works in the I2 C
protocol. This sums the total of occupied pins to five.
There is also in the original Trackuino design a basic
voltmeter that estimate the tension of the battery which
implies that all the analogue pins are now allocated.
The requirement Req-5 imposes that the command
and data handling system mimics the final BEXUS mission. This can be achieved by acquiring on one hand
science data and one the other engineering data that
would then be stored while a sample of the science
data and the comprehensive housekeeping information is downlinked to ground. The Trackuino system
possesses, as stated before, housekeeping sensors that
generate data which can be transferred to ground. The
possibility to add an interface to communicate with an
instrument to receive scientific data or at the very least
dummy data makes the system meet the requirement.
The connexion can be made easily with the Arduino
module on the serial or USB port.
The storage of data can be achieved through two
options : either by an USB key in the Arduino’s port
or by an SD card. The former option does not allow to meet the requirement Req-5 as the science data
would be conveyed to the board most certainly by
means of an USB interface. The latter implies that another interface must be installed to connect the card.
This hardware exists off-the-shelf. A micro SD Shield
available at Sparkfun Electronics provides such capabilities and has the great advantage of not interfering
with Trackuino as the pins used by both systems are
different. A micro SD card can store up to 32 GB which
largely covers the volume of data generated by the inSwiss Space Center / LPHE
Issue 1
strument and the housekeeping data.
According to flight predictions generated by the
University of Wyoming Balloon trajectory forecast system [16], the payload may travel long distances (more
than 200 km depending on the wind) and may land in
any kind of terrain (even in lakes or rivers). The acoustic device on the Trackuino may then prove useless as
its action would deplete the battery quickly and most
likely before the arrival of the recovery team. Moreover, the buzzer adds weight to the design and therefore reduces the balloon performance. Hence we will
remove it for our applications.
The Trackuino project proposes also a software. This
software controls the measurements taken every second, the GPS chip and the VHF transmitter. The Arduino softwares are implemented in a C-like language
which is therefore easy to understand and master. The
Trackuino software has to be adapted for further measurements (more sensors, compass read-out and USB
bus data acquisition) as well as for storage through the
micro SD card. This can be achieved fairly easily and
quickly as Arduino code exist for each instances. The
work on the software would rather require integration
of spinets than writing new codes.
The Trackuino system has already been used on several flights (even one across the Atlantic). However,
it would require a lot of testing, qualification as well
as sensors calibrations. On the telemetry side, the
frequency that carries the informations (a radio amateur one) is 144.800 MHz with a transmitter power
of 300 mW. On the website of the project, the recommended antenna is a “do-it-yourself” quarter wave
ground plane for a subminiature version A (SMA)
connector with four tubes radiating at 90° with a 30–
40° angle from the horizontal. This design may well
be sufficient to receive the information throughout the
flight provided that the line of sight to the balloon is
guaranteed.
The Arduino board operates on a 5VDC and 3.3VDC
tension, but must be supplied by a 7 to 12 VDC tension.
On the project webpage, no mention is made about
the battery. There are lithium backpacks for Arduino
as well as standard 9VDC battery option. Trackuino
consumes 200 mA for a 7.5 VDC (2 W with margin and
new sensors) reference voltage when transmitting via
the HX1 VHF module. Each pin of the Arduino board
can draw up to 40 mA and 200 mA on VCC and GND
pins [10].
According to the above discussions, it arises that
Trackuino can be adapted to suit the need of the balloon flight. The requirement that state that the temperature should be sufficient for the electronics to operate
can be achieved with a low cost polystyrene foam box.
Additional capabilities of temperature regulation can
be added through electrical resistors that are controlled
by Trackuino thanks to the temperature sensor. If the
page 24 of 67
Issue 1
T T
Compass
GNSS
V
P
A/D convert
Science
OBC Science
OBC Engineering
Thermal
DSU
T/M
VHF
SPOT
T T
12
P
Point-to-point Analogic
OBC Engineering
Arduino Board
USB Interface
Science
I2C Protocol
GNSS
V
OBC Science
Compass
Digital Built-in Ports
T/M
VHF
DSU
Thermal
Figure 5.2: Flight Trajectory Prediction, burst at 32 km
for 11 of November, launch at 7 am and the VHF antenna
144.800 MHz
proposed design. – Credit : Google Earth & Trackuino
website
Figure 5.3: Proposed block diagram for the housekeeping
concept. Links in dashed lines represent possible capabilities
Trackuino is adapted to fit the augmented capabilities
required and provided qualification tests, we are con- rectly picked up by radio amateur along the path of the
fident to say that this system will allow to achieve the balloons. Moreover, a stand-alone localisation device
mission’s objectives.
would relay via satellite the position of the payload
(unfortunately not the altitude) to an internet service
5.3.2 Housekeeping Architecture Proposal ensuring that the requirement Req-1 is met.
The housekeeping architecture would be composed USB Science bus The interface between the science
of several subsystems which are discussed in details
instrument read-out device and the Arduino
below. The main driver is to provide an integrated
board will be an USB wire, but further informahousekeeping system to support the operation of the
tion is not yet available. In the interest of savpayload. This proposal is based upon an adaptation
ing the energy of the batteries, the science instruof the Trackuino board. Schematics of this architecture
ment will enter its operational mode only when
are given in the appendix C.
at a given altitude deemed sufficient to access the
Measurements of the different sensors (GPS and
events measured. This feature may not be impletransducers) would be recorded once a second while
mented as the instrument read out may posses
data from the magnetometer would be retrieved more
built-in storage capabilities.
often (at least at a frequency of 5 Hz) to be able to
sample the rotation of the payload more efficiently. Batteries The two options for the Trackuino power
Those data would then be stored along with the scisource are a rechargeable lithium backpack or
ence data before being transmitted to the ground. This
9VDC batteries stacked in parallel to increase the
would certainly not be compliant with the APRS stancurrent that they can deliver. The lithium backdard which means that the messages would not be corpack are light, cheap (they are rechargeable) and
page 25 of 67
adapted to Arduino, but may not be interfaced
with the science part which means that it would
require two different power system. On the contrary, 9VDC batteries are easy to interface with
other technologies, but heavier and much more
expensive. The lighter option and most adapted
one to the duality of the power needs (Trackuino
on one side and the detector on the other) is to
separate the batteries as well. The selected battery subsystem is a composite of one high capacity
Lithium backpack from Liquidware (2200 mAh)
and two 9V batteries from Ultralife (1200 mAh
each). This selection is based on the study of the
power budget – Tab. 5.5.
Trackuino modified The core of the system is based
on the Trackuino shield modified to accommodate
it to the requirements. After the extensive discussions about the capabilities of the Trackuino system, we only summarise here the hardware used.
Venus 638FLPx chip This GPS which can be
bought at Sparkfun Electronics works on the
L1 frequency only yielding best estimate of
the position to about 2.5 meters. It can be
configured to relay much more information
than simply the position and altitude. The
firmware posses a debug mode which exploits this. It requires either a passive or an
active antenna, however as the payload will
reach altitudes higher than the 18 km operational limit, we recommend the use of an
active antenna.
Issue 1
environment of the science instrument to allow for eventual thermal regulation as well
as post calibration of the data and another
one that would be located outside the payload. The temperature range of the LM60
used here is -40 to +125°C. As the temperature outside the payload will drop below
the minimal operational voltage, the outside
measurement may only work for part of the
flight. This is a very widely-used cheap sensor working at a 2.7–10 VDC tension and providing outputs that are, during operations,
always a positive voltage.
Pressure Sensor The pressure sensor shall be
able to measure pressure from 0 to 1 bar,
work on a 5 VDC basis and output its measurement in analogue form on one wire.
Moreover, it must withstand below 0°C temperature in operation. The only sensor that
was found to operate under those circumstances is the Honeywell 40PC Series. This
is a relatively expensive sensor compared to
the price of the hardware and is sensitive to
electrostatics. It should be handled and use
with care, but has a high sensitivity of 3.87
mVDC per hPa (at 25°C and 5 VDC).
Voltmeter A rudimentary voltmeter provides a
estimate of the health of the batteries by using two resistors (see schematics, appendix
C.2). The capabilities of this sensor shall be
investigated and the possibility to remove it
in order to recover one analogue pin shall be
discussed after testing. This should be considered when soldering the Trackuino shield.
GPS Antenna The antenna connected to the GPS
chip needs to be light and to use low power.
Buzzer The buzzer will not be used.
One solution is to the Sparkfun Electronics
Antenna GPS Embedded SMA which has a Magnetometer There are two off-the-shelf options for
gain of 3 dB, weights 18 g and draws a curthe magnetometer. They both use the same magrent of 12 mA.
netometer chip : the HMC5883L. The first – GY-27
for Arduino by DealExtreme – possesses a magVHF Transmitter module The VHF transmitter
netometer as well as an accelerometer, but is very
is produced by Radiometrix under the prodpoorly documented and does not provide any
uct name of HX1. The transmitting power is
specification on its resolution nor on its preci300 mW (24.7 dBm nominal) with a maximal
sion. On the other hand, the second – Triple Axis
data rate of 10 kbps. This is a downlink only
Magnetometer Breakout by Sparkfun Electronics
system.
– does not have a accelerometer, but is very easy
VHF antenna The VHF antenna has already deto use and to interface as it uses the I2 C interface.
scribed in section §5.3.1.
As there is no information about the orientation
Temperature Sensors The two temperature senin space and the payload must stay vertical. This
sors on the original design are used for incould be a sufficient solution for an early flight
ternal and external measurements. One is
or an early prototype. A third option arise : to
located on the board while the other can be
built out own sensor using an accelerometer and
interfaced through a terminal block. On our
the HMC5883L chip. The tilt compensation is
design (See appendix C.1), we propose that
done fairly easily using trigonometric relations.
both sensor should be used externally : one
We recommend to begin with the easy-to-use sento measure the temperature in the immediate
sor from Sparkfun Electronics and move on to a
page 26 of 67
better measurement using an accelerometer once
the technology is mastered.
Data Storage Unit The data storage unit is a micro SD
card and a microSD Shield for Arduino again from
Sparkfun Electronics. The great advantage of this
part is that it is another shield so it can be stacked
on Arduino Uno and possesses a 3.3VDC regulator which will ensure that the micro SD card does
not burn. No pins interfere with the Trackuino
system which is a great advantage.
Reliable and robust localisation device As already
mentioned, the line of sight between the balloon
and the ground station may be severed at some
point during the flight. This calls for another system of localisation. MeteoLabor, the company
that sells balloons to MétéoSuisse recommend to
use a SPOT Satellite GPS Messenger which relies
solely on satellites to relay the information via the
web back to the ground station. This is an expensive hardware with a paying service. However,
a deal with MeteoLabor can be reached as they
tested some for ESA and do not use them often.
The position of the device (and not the altitude)
can be measured up to every 10 minutes at any
altitude. This features is also present on BEXUS
balloon in the form of an ARGOS transmitter.
Issue 1
5.4
Software
We already discuss the capabilities of the avionics of
SHAGARE. The main idea is to keep the system simple
such that the development time is minimized. Such
that the main goal which is to prepare the way to the
BEXUS flight can be reached in a near future. With this
in mind, Trackuino was modified to suit our needs on
the hardware side. It comes with a dedicated firmware
that can run on an Arduino board which should be
modified as well. The modification of the software
will mainly imply to add the capability to log data and
read more sensors and maybe actuate some others as
well as making the system more robust by adding a
safe mode.
As said before, the code in which Trackuino is written is the language used by Arduino which is pseudoC. Students from EPFL are not going to be overwhelmed by the complexity of the code which isobjectoriented structured. The basic capabilities of the code
include the sampling of the GPS position, the reading out of the two sensors as well as the voltage, and
the time stamping the data. The downlink only communication through the HX-1 radio-transmitter is also
ready to use.
It can be noted that the software described in the
following is represented in a block diagram on Fig.
5.4 and assumes that the instrument possesses its own
data storage unit and an active thermal control subsystem. There is one major requirement that is deduced
from the storage performance of Arduino for its code
less than 32 kb (Req. 8)
Thermal The thermal compensation capabilities of
the proposed design are very limited.
The
electronics would be warmed up using handwarmers. The heat output of must be tested to
see if they would be enough to ensure the success 5.4.1 Initialisation Mode
of the mission. If not further thermal subsystems
must be developed (see Further Developments 5.4.1.1 Time Synchronization
bullet).
Upon powering of the Arduino board, the software
starts by initialize itself. The first step is to provide curFurther Developments If the thermal system must be rent time in order for the clocks to synchronize which
more specialised than simple hand warmers, the means that Arduino is connected to a computer. The
possibility of implementing an electrical resistor time could also be provided by the GPS chip to prevent
to warm up in a more controlled fashion can be floating time measurement in case of synchronization
studied.
failure.
If the value of the science data depends greatly
on the output of the magnetometers, its measure- 5.4.1.2 Self-Test
ment can be improved by using an accelerometer Upon completion of the time synchronization, initialas previously discussed.
ization begins by checking that the different sensors
The installation of a humidity sensor could be read reasonable results and that the GPS can provide a
achieved if a heavier use is made of the I2 bus fixed position to a certain margin (TBD) during a certain period of time. Those values are communicated
for Arduino communications.
via the serial port of Arduino and the HX-1 transmitIf there is not interface via USB cable which would ter to monitor from the computer as well as to test
signify that the instrument possesses its own the transmitter. If the tests were to fail, they should
data storage unit, a power switch from Trackuino be restarted after a certain delay as the failure might
should be implemented.
be caused by difficulties to acquire GPS signals. After
page 27 of 67
Issue 1
Initialisation
mode
§5.4.1
Current time
Synchronise
time
GPS time
Self-test
Is test
successful
?
yes
no
Loop
counter
Is # of
loop < 3?
no
STOP Initialisation
Error
Safe mode
§5.4.4
yes
Close
serial
connection
Flight
Mode
§5.4.2
Attitude
reading
Wait
until next
200 ms
no
Count
attitude
readings
Is # of
readings
=5 ?
Detector
powered
up
Detector
powered
down
yes
Is > 15
km ?
no
no
Has
landed ?
yes
yes
HK + GPS
measurements
Batteries
ok ?
yes
Data
packet
to T/M
and DSU
Adjust
Heating
Power
Save mode
§5.4.3
no
Safe mode
§5.4.4
Figure 5.4: Block Diagram for the SHAGARE avionics system software assuming that the instrument possesses its own
DSU and an active thermal control subsystem.
page 28 of 67
Issue 1
three unsuccessful self-test, the initialization is canOnce that SHAGARE has landed (which is detected
celled, the system issues an initialization error and by the altitude not varying over a long period close at
enter Power Save mode.
plausible altitudes, i.e. below 4 km above sea level),
the software enters a power save mode.
5.4.1.3
Initialization Mode Termination
5.4.2.4 Instrument Control
Upon passing the self-test, a message is broadcasted
that the software is ready to enter flight mode. Upon As described already in §4.4, the detector does not
acknowledgement, the user will send a command to need to be turned on before at least 15 km altitude.
Under the condition that the instrument can withstand
close serial communication2 .
an initialization at 15 km altitude with low temperature and pressure, it could be turned on only when
5.4.2 Flight Mode
the balloon is higher than this altitude in order to save
This mode is entered upon completion of the initial- batteries.
ization. It is basically a loop on several blocks that
have to be carried out during the flight. Those blocks
are described in the following.
5.4.3
Power Save Mode
There are two ways to enter this mode. In case of
failure to initialize the software or once SHAGARE
5.4.2.1 High Sampling Rate Readings
has landed. The purpose of this mode is to wait for
recovery and therefore all measurements are stopped
As the payload might spin with a frequency of once
as well as the detector if it was not already the case
to twice a second, a minimum sampling of 5 Hz is
and emits a continuous signal for a short burst every 10
used to read out the compass such that we are able to
seconds to help the final localization of the device. The
reconstruct the attitude variation.
power consumption is therefore reduced and all the
data is saved on the card. Thermal control is reduced
5.4.2.2 Low Sampling Rate Readings
to a minimal, i.e. making sure that the temperature of
the box stays above the survival temperature.
This low sampling rate measurements is a block in
which measurements are made every second and will
incorporate all sensors but the compass which include 5.4.4 Safe Mode
GPS position, temperature, pressure, voltage and hu- The purpose of this mode is different from the power
midity if implemented.
save mode as it can be suddenly entered if the voltage
5.4.2.3
Housekeeping & Telemetry
Those data are then processed to evaluate whether the
batteries are still delivering a voltage within acceptance. Upon failure of this condition several times in
a row (which is to yet to be determined), the software
should enter Safe mode.
After the battery test, the data are timestamped every second, saved on the Data Storage Unit as well
as sent to the VHF transmitter. Throughout the flight
the telemetry will send a data packet containing at
least the timestamps, position (latitude, longitude), altitude, atmospheric pressure and battery state. If possible, the temperatures, the pressure and the attitude
will be downlinked as well to estimate on the ground
the well-being of SHAGARE.
The thermal control block is hypothetical as it allow to control the heating on-board. Further investigations (notably in the instrument thermal stability
requirements) are needed to define better the thermal
control.
2A
variation of this phase is not to wait for the command and
shut the serial communication down immediately.
of the batteries fall below a certain threshold which
remains to be established. The goal of this mode is to
maximize the duration during which data can be read
and recorded. The telemetry stream is shut to save
power and the sampling rates might also be reduced
if tests (§5.6) show that they are high enough. During
this mode the thermal control is reduced to a bare
minimal.
5.5
Trade-Off Evaluations Criteria
In this section, we present the different key criteria
that were and are useful in the decision process. SHAGARE is a small, cheap and relatively short term mission. Moreover, the resources are limited to two people
from the Space Center. Here are the most important
ones to us :
Robustness The hardware should be designed such
that it withstands the impact upon landing.
Low development risk Low involvement of new,
poorly tested technology versus old reliable technology. Furthermore, the mission goals are well
page 29 of 67
Issue 1
Robustness
Low development risk
Development Time
Simplicity
Accessibility
Cost
Criteria Y
-
-1
-1
+2
+1
-2
+1
-
+1
+0
-1
-1
Development Time
+1
-1
-
+0
-1
-2
Simplicity
-2
+0
+0
-
-1
-2
Accessibility
-1
+1
+1
+1
-
-1
Cost
P
+2
+1
+2
+2
+1
-
1
0
3
5
-1
-8
0
16
15
18
20
14
7
90
17.8
16.7
20.0
22.2
15.6
7.8
100
3
4
2
1
5
6
Criteria X
Robustness
P
+3(N − 1)
Importance in %
RANK
Table 5.2: SHAGARE – Weighting of the different
evaluation criteria. The positive marks mean that Y is
more important than X and negative the opposite. 0
signals that they are equally important. 1 is slightly,
2 more and 3 much more.
designed and should not be adapted during the ple of usage of this methodology is given in appendix
development process. The goals of the mission D.1.
should always be in focus of the development.
Development Time The SHAGARE project should
not last more than a term which implies that the
development time should not be underestimated
and imply delays.
5.6
5.6.1
Testing & Validation
Testing Plans
We will expose a few of the tests that will have to be
Simplicity The complexity is to be kept to a mini- made to ensure the security and success of the mission.
mal. This allows to reduce problem sources and This is done to verify that the requirements are met.
decreases the development time.
This list is not exhaustive and will be completed.
Accessibility The simplicity with which the components can be reached once SHAGARE is inte- 5.6.1.1 Thermal and Pressure Tests
grated.
For the thermal testing two things have to be considCost This project is a mission “path finder” for the ered : the electronics and the detector.
The first test will be to determine if the overall elecBEXUS HAGARE and in such the hardware will
be different on HAGARE and therefore cheap off- tronics functions at the expected temperatures. For
this the whole design has to be mounted in a refrigthe-shelf components should be chosen.
erator that can achieve at least −40°C with thermal
Those drivers will impact on the design choice for protection. The aim of this is also to determine which
SHAGARE and therefore they must be ordered to de- are the warmest and coldest components. The tempercide – this weighting is given on Tab. 5.2 and an exam- ature of the refrigerator will also have to be adjustable
page 30 of 67
to test the experiment at different temperature in an
attempt to determine the response of the electronic (in
temperature and efficiency) as a function of temperature.
The second part of the tests aims to determine what
is the temperature profile inside the structure. To ensure that the design survives the pressure condition it
will have to be tested in near vacuum, using a vacuum
pump.
5.6.1.2
Mechanical test
Issue 1
several temperatures ranges (room temperature and
between 0–10°C).
5.6.1.6
Batteries Voltage Measurement
Trackuino has a built-in voltage measurement, however the accuracy of this measure is much lower than
a voltmeter. As the software depends upon this value
to enter Safe mode, it would be wise to test its reliability such that safe mode conditions can be derived
from a trusted source.
This test will have to be carried out when the house- 5.6.1.7 SHAGARE Recovery and System Reliability
keeping part is integrated inside the protective structure. As for BEXUS [3], it should withstand typical The main cost in a SHAGARE flight is the instrument
that cost almost 4000 CHF. To ensure that this valuable
shocks for landing i.e. :
detector is retrieved (which is one of the requirements),
1. Drop from an altitude of maximal 3 meters
a recovery team (whose mobility is ensured by a car)
must be trained to get to the balloon. The system
2. Mechanical loads of 30× maximum its mass
as a whole should be tested in a real environment.
The test would therefore be a meteorological balloon
5.6.1.3 Data Storage
flight without the instrument for a maiden flight. The
Once the software for the Trackuino is adapted to our Trackuino avionics would be exactly the same as for
requirements, it will have to be tested to ensure that it the real SHAGARE mission with the goal to verify the
is capable of storing all the data, housekeeping as well flight system and to train the recovery personnel with
as science. By changing the data rates (frequency of a cheaper mission.
readout of the sensor and detector) the idea is to find
the operational limits of the design and the optimal
readout frequency. The data volume for the whole
mission is yet to be defined as the science instrument
is not yet fully characterized. We estimate however
that the volume will not be more than 16 GB for a
maximal three hour flight.
5.6.1.4
Data Transmission
5.6.2
First Validation of the Concept
With the short time at our disposal, we carried out
simple thermal tests on a prototype of an Arduino
UNO with temperature and light sensors connected to
a SD data logger. The idea was to prove that an Arduino is easy to handle and that the data storage can be
achieved. We ordered from http://www.playground.
ch a starter kit and a SD card shield.
Using a receiving antenna, we will test the data transmission rates and limiting factors. In order to satisfy 5.6.2.1 Arduino Starter Kit
requirement R1 we have to make sure that the GPS
data can be send reliably for the duration of the flight,
Photoresistor
Thermometer
and if possible in the flight thermal conditions. This
will also be done for the readout of the temperature
and pressure sensor for requirement R4.
Battery
5.6.1.5
Batteries Capacity
As stated in the power budget (§5.5), one SHAGARE
flight should embark one lithium backpack and two ultralife 9V batteries. The maximal lifetime on the power
Serial
profile used is 7.15 hours which is largely more than
port
maximal estimated time of flight of 3 hours (§5.3.1).
Using a depth of discharge of 40%, this 3 hours capacSD Card
Arduino UNO
ity can be achieved. However, this needs to be tested.
The test setup is straightforward : switch the device on,
switch the avionics mode to flight mode and measure Figure 5.5: Arduino UNO with a thermometer, a photorethe time at which the batteries are too low to power sistor and a SD data logger.
the different subsystems. This could be repeated for
page 31 of 67
Issue 1
Thermal Tests
440
5.6.2.2
SD Card Shield
This shield was order to the same retailer, but we had
to assembly it first. This SD card is quite neat as it
has an built-in quartz clock and a battery. The soldering lasted about 20–30 minutes with inexperienced
hands. The tutorial that described its assembly was
comprehensive (there is a picture for every step !).
Once mounted, we pulled off data logging quickly
despite electrical contacts that were not optimal : the
shield is not designed for prototyping but for soldering. One good thing to do would be to replace the
headers by two ways headers such that jumpers can
be inserted. The different tutorials were found from
this link : http://adafruit.com/products/243.
360
10
15
20
25
Time [min]
30
35
340
40
25
500
20
400
15
300
10
200
5
100
0
0
10
20
30
40
50
Time [min]
60
70
80
0
90
30
800
20
600
10
400
0
200
−10
0
10
20
30
40
Time [min]
50
60
Light [arbitrary]
5
Light [arbitrary]
0
0
Temperature [degree C]
Thanks to the shear number of tutorials and code
spinets available on the web, there was not many difficulties to understand and run the different experiments we fancied doing. We reckon one problem
though : on a Linux-based computer, the user/player
should make sure that access to its USB port is not
restricted to its super-user only (root). Arduino has a
basic code editor with its own compiler and serial port
monitor which makes the system very easy to prototype and use. This freely downloadable editor comes
with dozen of example codes ranging form basic LED
controls to much more advanced communication with
Wifi/Ethernet protocols.
380
5
We managed to mount and code every circuit within
2 hours : Christmas-like LEDs blinking, beeping to
a song as well as measuring room temperature and
its brightness. During the following hours we managed to implement a circuit that would start measuring
temperature and brightness on command via buttons,
communicate those reading to a computer via a serial
cord and display them on the screen. The follow-up
to this experiment was to implement two ways communications to Arduino via the serial chord. Those
kind of software are less than 180 lines long including
comments.
400
Light [arbitrary]
420
The starter kit contains an Arduino UNO, a bread- 5.6.2.3
board and several different components (LEDs, photoresistors, piezo-electric device, buttons, ...) that en25
abled us to try simple circuit. There is also an absolute
starter booklet that describes a few circuits as well
as the codes to run them correctly. Moreover, count20
less website give schematics and code spinets to create
up to very complicated project. In our case, all in15
formations about the software and the hardware are
described on the Trackuino website or on the different
pages of the components (for example, the compass
10
comes with a complete code that uses the 3 axis magnetometer.
0
70
Figure 5.6: Temperature tests with the device shown in Fig
5.5.
TOP : Room temperature, more lights are switched on in
the middle.
MIDDLE : Outside (about 2–5°C) and then inside.
BOTTOM : Freezer (30 min), Fridge (20 min) and then
room temperature. Light variations due to the plastic cover
used to protect the device.
page 32 of 67
Issue 1
An Arduino was setup up with a thermometer
(LM60, range -40 – 125°), a photoresistor and the SD
data logger as pictured on Fig. 5.5. Once the time
was synchronized via the serial bus and the computer,
the test starts and logs a timestamp (milliseconds since
start-up), the date with the hours, the temperature in
degree Celsius and a value for the photoresistor.
coping with such low temperatures. It may stop working because it is frozen below -40, but the temperature
measured before, may in fact be hotter than what it
really is outside due to slow change. During the descent, the temperature gradient is positive, the outside
temperature should be trusted. The negative gradient
give an approximate value of -2.85°C/min while the
positive is an logarithm (!) T ∝ a ln(t [min]) with a
Room Temperature The first test carried out is a tem- scaling factor of a ∼ 2.6 °C.
perature stability test over 38 minutes, to check that the
cabling was correctly performed and that Arduino was Humidity The humidity was not measured during
behaving as expected. The result of the test is visible the tests but was an issue as some of the test had to be
on Fig. 5.6. We see a slight noise of about ±0.3°during stopped because the device was not behaving correctly
the test which is satisfactory for our application. The due to a thin cover of condensation all over the device
constant decrease in light reflect the change in lumi- after great positive thermal shocks.
nosity as the Sun was setting during the experiment in
the room and is not an artifact.
Prototyping This setup was a very alpha version of
the device and therefore may not be representative of
Cold Temperature The second test lasted 90 min- the performance of Trackuino once in flight. Moreover,
utes. After start-up, the device was placed outside the connections were not properly made here (using a
(outside temperature about 2°C at the beginning and breadboard) and therefore more exposed to humidity
afterwards 5°C as snow turned to rain). After 35 min- and noise then PCB and protected sensors.
utes, it was brought back inside. The data reveal (Fig.
5.6) that the circuit needs some time (about 7 minutes, consistent with other similar experiments) to cool Arduino Resilience As proved by the harsh temperdown and then stabilises. Upon re-entry, the device ature test carried out, we can say that the Arduino
temperature gradient is better at the beginning but sta- board is very resilient. It supported more than one
bilises slowly afterwards as it needs about 30 minutes hour in different freezer with temperature ranging
to come back to its original value. Again, we can see form -10 to -20°C. Even though the prototype was not
protected enough (the fault is surely to blame on the
the light outside slowly disappearing.
battery) and stopped working, Arduino can be used
straight out the freezer via the USB cable.
Very Cold Temperature Very cold temperature
We can conclude that those tests are sufficient to
means below zero temperature. This was achieved
carry on with Arduino and Trackuino for the next
by placing the device in a freezer after initialization
steps. However, a solution to fix the positive logafor 30 minutes and then in fridge for 20 minutes and
rithm behaviour must be found.
then for the time remaining at room temperature. The
device was put inside a plastic bag to try to protect
from humidity (which is reflected in the very unstable
5.7 End-to-End Mission Summary
light curve). The data show (Fig. 5.6) that it took about
20 minutes for the device to get from 22°C down to -9°.
The peaks in temperature are when the experimenter In this section, we describe the SHAGARE mission
handled the device. The experiment was stopped a bit from the beginning of assembly to post flight analybefore stabilisation because the condensation on the sis to give a reasonable idea of how – in our view –
the HAGARE project should be implemented. Several
device was a concern.
budgets are discussed in this section with different
margins. The margins are chosen as follow :
5.6.2.4 Lessons Learned
50% corresponds a very rough estimate without exAfter those tests a few remarks can be done :
perimental data upon which to rely.
Temperature Gradients The temperature gradient 30% reflects an estimation extrapolated from data or
are not very well followed by the electronics especially
the component needs modifications.
the positive one. The flight lasts about 1h50 (according to simulation, see 5.7) and the temperature varies 10% means that the data has been measured or that
from about 10°C on ground down to -60°C outside
its value is clearly defined without need of modithe box. The external thermometer will have trouble
fications.
page 33 of 67
The total length of a SHAGARE project is such that
the project (at least from the engineering point of view)
should last one semester maximum. The detailed
planning is yet to be established, but is estimated in
every paragraph of this section.
The planning on one term for the SHAGARE project
is presented on table 5.3.
Mass Budget The mass constraint is analysed in the
mass budget – Tab. 5.4 – which yield a total balloon
mass of 1496 grams with a design margin of slightly
more than 30% with the scientific payload weighting
less than 30% of the total mass. If the actual mass
budget of SHAGARE is less than the 1500 grams, the
balloon could go even higher before burst [8]. The
actual mass also determine whether an active thermal
subsystem can be implemented.
Power Budget The power budget is shown in table
5.5. The chosen architecture as discussed in §5.3.2
for the power source is composed of one rechargeable
lithium battery pack and two non-reachable 9V batteries to power the instrument and its read-out. The
housekeeping part of the SHAGARE system draws
309 mA with a 17% margin while the scientific payload draws 300 mA with a 50% margin. The avionics
can draw enough power from the batteries and there
is still about 190 mA of reserve that could be use to
power a heater. The power for scientific payload however is tight as there is no reserve. The figures are
guesses of the currents needed such that there might
be a need for another battery.
Issue 1
List). The balloon already includes an appropriate
parachute for a cost of 540.-. About 9 m3 of helium
must be used to fill the envelope of the balloon [8].
Contacts with Meteolabor SA and MétéoSuisse must
be established very early (in the first two weeks) to
ensure that the launch will take place by the end of the
semester as the cooperation of MétéoSuisse is going to
be very important. MétéoSuisse is used to launch such
small high altitude balloons as they launch several
of them every week from Payerne Airport in canton
Vaud.
The order for the augmented Trackuino (See component list – Tab. C.1) is also to be placed during the
first two weeks of the semester as components must be
shipped from abroad (for instance, the VHF transmitter is manufactured in the UK). We recommend that
the time between the placement of the order and the
arrival of the components is devoted to administrative work (license for the VHF usage, find the testing
facilities, find a VHF receiver, . . . ) as well as software preparation (an Arduino and a SD data logger is
available from the Space Center). It should be stressed
that all the components for the avionics arrived not
mounted and are going to have to be soldered which
we estimate will take two days. The VHF antenna
is not included in the component list and should be
manufactured. The box is to be painted in a bright
color and EPFL plus Swiss Space Center stickers applied on its surface. A piece of paper explaining what
SHAGARE is, that is not dangerous and the telephone
number of the flight director should be visible in case
the balloon is found by locals before the teams arrive.
As soon as the different boards are ready, avionics
testing starts such that a maiden flight can be carried
out. They can coincide with the integration of the
components. The payload is placed inside a Sagex
box of about 300 mm by 250 mm by 200 mm and the
thickness of the wall should be 25 mm such that there is
a passive thermal protection. The detailed disposition
is also to be designed during integration or before if
possible. Integration of the detector should start as
soon as the LPHE has developed an read-out system.
The tests carried out are at least those described in
§5.6 and will last (with design iteration) maximum 6
weeks.
Cost Budget The cost budget presented on Tab. 5.6.
The 2466.- Swiss Francs represent an estimation of the
price for one mission if the complete hardware is to
buy. Moreover, this budget concerns only the engineering part and does not include the price of the detector nor its electronics. Depending upon the impact
on the hardware, it may be reused for another later
flight which would be much more time effective. The
most expensive part (detector excluded) is the the balloon which represents nearly one fourth of the total
cost and is of course not reusable. The second most
expensive item on the budget is the cost of the facilities usages in Payerne plus a reserve for any extra cost
The following sections refers to the maiden flight
for recovery and therefore, this price cannot be refined
campaign as well as the final flight with the instrument
better.
on-board.
5.7.1
Assembly, Integration & Testing
In order to ascend to a 30 km altitude or higher with the
best balloon that can be purchased from Meteolabor
SA, the payload mass should not be more massive than
1500 gr. Meteolabor are the provider of high altitude
balloons for MétéoSuisse (See Appendix B, Contact
5.7.2
Pre-Launch
The pre-launch phase consists of the thorough checking that the equipment and the balloon are ready to be
deployed in the air and in the field. This phase should
take up to one week.
page 34 of 67
Untitled Gantt Project
Gantt Chart
2/18/13
2/18/13
2/25/13
2/25/13
3/4/13
3/5/13
4/22/13
4/12/13
4/22/13
4/19/13
5/10/13
4/23/13
4/26/13
4/29/13
5/3/13
5/10/13
5/13/13
5/17/13
5/20/13
2/18/13
2/22/13
3/1/13
3/1/13
3/4/13
2013
Assembly starts
3/31/13
4/7/13
4/14/13
Avionics ready
Maiden Flight
4/21/13
4/28/13
5/5/13
Term ends
3
Dec 27, 2012
2nd Avionics
2nd
ready
Flight
5/12/13
5/19/13
5/26/13
6/2/13
Week 10 Week 11 Week 12 Week 13 Week 14 Week 15 Week 16 Week 17 Week 18 Week 19 Week 20 Week 21 Week 22 Week 23
3/24/13
3/3/13
3/17/13
Week 9
Table 5.3: SHAGARE Gantt Chart for spring term
2013.
3/10/13
2/24/13
Term starts
Week 8
End date 2/17/13
Term starts
Project starts
Order Parts
Administrative work
Assembly starts
3/4/13
3/6/13
3/15/13
4/2/13
4/15/13
4/22/13
4/23/13
4/23/13
4/29/13
4/29/13
5/6/13
5/13/13
5/13/13
5/20/13
5/24/13
5/31/13
5/31/13
Begin date
Assembly
Testing
Administrative Flight prep
Detector integration
Order parts for 2nd flight
2nd Assembly and testing
Avionics ready
Pre-Flight
Maiden Flight
Maiden Flight Campaign
Post-flight analysis
2nd Avionics ready
2nd Pre-Flight
2nd Flight
5/20/13
5/27/13
5/31/13
Name
2nd Flight Campaign
2nd Post-flight analysis
Term ends
page 35 of 67
Issue 1
5.7.3
Flight Campaign
As previously discussed, the launch would take place
at Payerne to profit from the experience of MétéoSuisse there. The need in personnel is at least 5 divided
into two groups : a main team charged of the launch
and the recovery and composed of at least three persons (one flight director and 2 engineers). Another
team – the support team – is to be dispatched to a
location from which the signal of the balloon can be
received through most of the flight. Two people are
needed here : one driver (preferably with good orientation and map reading skills) and one telecom engineer. The planning of this campaign will necessitate
at least one week and its carrying out one as well. As
described in the section discussing the software (§5.4),
telemetry will be sent every second. Each team will
also receive via internet the position of the balloon
given by the SPOT tracking device which updates the
coordinates every 10 minutes. Normal VHF telemetry
is broadcasted every second.
Issue 1
sible only if the launch conditions are such that the
balloon does not cross the Alps. The time of flight
should be enough for the main team to move out to
landing zone. The total ascent time is around 1h50
minutes as predicted by the University of Wyoming.
If this feature is implemented in the final design, the
instrument will be switched on above a certain threshold which has been established to be 15 km high as the
gamma-rays cannot be measured at the energies with
which we are experimenting. This feature may not
be very useful if the batteries can provide power for
much more than the time of flight, however it might
be critical if this lifetime of the battery is of the order
of the flight duration.
5.7.3.3
Burst
The burst is the moment at which the envelop of the
balloon is too thin to resists the tension applied by the
expansion of the helium inside. With the total mass on
HAGARE, the burst should occur at between 28 and
32 km altitude. There is a slight dependence on the
mass as the volume of helium inserted can be reduced
5.7.3.1 Launch Decision
and therefore rising the burst altitude. There is no
The decision to launch is mostly constrained by the feature of the on-board software nor of the hardware
weather as the balloon may fly up to several kilome- to detect the burst. However, the altitude will start to
ters across the Alps depending on the wind. We pro- fall quickly.
pose a online software developed by the University of
Wyoming [16] to predict the trajectory based on global
5.7.3.4 Descent
winds forecasts. This prediction can be compared to
others (notably MétéoSuisse) before reaching the de- The typical descent velocity is 8 m/s for BEXUS, may be
cision. If the agreement is to proceed with the launch, a bit less for the SHAGARE mission as the parachute
a support team is to be dispatched to the some high is different. The descent time is about 40–45 minutes.
ground location in the middle of the ground track such As soon as the support team is losing the VHF signal,
that the VHF signal can be picked up. The team who is they will pack their equipment and move towards the
burdened with the responsibility of the launch has also landing zone. Upon crossing the 15 km threshold, the
got a receiver for the early ascent. The decision is taken instrument is shut down. If both teams lose telemebefore the start-up of the avionics on-board. A count- try, they will rely on SPOT to locate and estimate the
down sequence is to be prepared in advance to account landing point.
for the different phases (equipment deployment, software initialisation and test, if applicable instrument 5.7.3.5 Recovery
test and inflation). As covered in the Assembly, Integration & Testing section, there is a possibility that the Once on the ground, the software switches the power
payload is found by locals or worse that it lands on scheme to power save mode which means that the
a tree or in water. Those risks have to be taken into emission of a signal is done ever 10 seconds to save
batteries as well as being able to receive it. Both teams
account at decision.
(the support team should arrive on zone after landing)
rely on SPOT telemetry as well as on a goniometer
5.7.3.2 Ascent
(if applicable) to locate SHAGARE. Once SHAGARE
During the ascent, the balloon has a typical vertical is secured, all systems are powered down, the flight
velocity of 5 m/s and a ground speed between 0 and train is disassembled and readied for transportation
10 m/s. The main team is responsible for picking up back to EPFL. The teams need to be equipped with
the telemetry until SHAGARE can be received by the ladders, knifes and mast to pick the payload up in
support team. Upon confirmation that the support heights (trees) or difficult areas. Before leaving the
team has acquired the signal, the people responsible landing zone, the equipment should be checked to
for the launch ready themselves for transportation to make sure nothing is forgotten or left behind. Once at
the predicated touch-down coordinates. This is pos- EPFL, it should be cleaned and stored.
page 36 of 67
5.7.4
Issue 1
Post Flight Activities
Post flight activities consist of data analysis on the
science part and drawing lessons learned from the
engineering that can be used to improve the design
on later SHAGARE-class or HAGARE-class missions.
Documentation of the results and the lessons learned
is another important task. This can last one or two
weeks.
page 37 of 67
System
Lift
Issue 1
Subsystem
Mass [kg]
Margin [%] Allocation [gr]
-1454
2
-1431
Balloon
-1500
0
-1500
Parachute
30
50
45
Nylon cable
6
50
9
Duct Tap
10
50
15
Structure
185
34
248
Sagex Box
150
30
195
Duct Tap
30
50
45
Epoxy
5
50
8
Thermal
25
30
33
Handwarmer
25
30
33
Electrical Warmer
0
0
0
Housekeeping
560
28
719
SPOT Tracker
150
10
165
Batteries
140
30
182
Trackuino
90
50
135
Digital compass
10
30
13
Data Storage Unit
15
30
20
Temperature Sensors
15
30
20
Pressure Sensor
15
50
23
GPS Antenna
30
30
39
Telemetry Antenna
15
30
20
Wiring
80
30
104
Payload
327
31
428
Hamamatsu C12137
117
10
129
Read-out
130
50
195
Wiring
80
30
104
BALANCE
-357
-4
Total mass
1143
31
1496
%
4.6
3.0
0.6
1.0
16.5
13.0
3.0
0.5
2.2
2.2
0.0
48.1
11.0
12.2
9.0
0.9
1.3
1.3
1.5
2.6
1.3
7.0
28.6
8.6
13.0
7.0
Table 5.4: SHAGARE – Mass Budget for the meteorological balloon
page 38 of 67
Issue 1
Ultralife Batteries
2
0
450
480
192
System
Subsystem
Current [mA]
Margin [%]
Allocation [mA] Voltage [V]
Power [mW]
Stand-Alone SPOT Tracker
Thermal
0
0
0
0
Electrical Warmer
0
0
0
5
0
Housekeeping
265
17
309
2054
Trackuino
200
15
230
7.5
1725
Digital compass
2.5
30
3.25
3.3
10.725
Data Storage Unit
2
50
3
3.3
9.9
Temperature Sensors
0.55
50
0.825
5
4.125
Pressure Sensor
10
30
13
5
65
GNSS Antenna
30
10
33
3.3
108.9
Telemetry Antenna
0
50
0
3.3
0
Wiring / Joule
20
30
26
5
130
Payload
200
50
300
2250
100
50
150
5
750
Hamamatsu C12137
Read-out
100
50
150
10
1500
Wiring
0
0
0
5
0
TOTAL DRAWN
465
31
609
4304
Batteries available
Voltage [V]
Weight [g]
Discharge
[mA]
Capacity
[mAh]
Ultralife Batteries
150
1200
9
37
Lithium Backpack
500
2200
5
60
Energizer
120
400
9
46
50
1200
10.8
31
Ansmann
SELECTED BATTERY SYSTEM
Units required
Margin [mA]
Margin [mW] Duration [min] 40% DoD [min]
Housekeeping
Lithium Backpack
1
191
446
427
171
Detector
Table 5.5: SHAGARE – Mass Budget for the meteorological balloon
%
0.0
0.0
48
40.1
0.2
0.2
0.1
1.5
2.5
0.0
3.0
52.3
17.4
34.9
0.0
page 39 of 67
Cost budget
System
Lift
Issue 1
Subsystem
Price [Fr] Margin [%] Allocation [Fr]
775
22
946.5
Balloon
540
10
594
Parachute (included)
0
0
0
Nylon Cable
25
50
37.5
Duct tape
10
50
15
Helium
200
50
300
Structure
50
50
75
Sagex Box
40
50
60
Duct tape (included in lift)
0
0
0
Epoxy
10
50
15
Thermal
40
39
55.5
Handwarmer
10
50
15
Electrical Warmer
30
35
40.5
Housekeeping
361
27
459
Trackuino
50
10
55
PCB manufacturing
50
35
67.5
GPS Chip
50
10
55
GNSS Antenna
10
35
13.5
Digital compass
20
35
27
Data Storage Unit
25
10
27.5
Temperature Sensors
0.5
10
0.55
Pressure Sensor
50
20
60
Telemetry Antenna
50
50
75
Batteries
25
50
37.5
Wiring / Small components
30
35
40.5
Ground Station
170
50
255
Antenna
75
50
112.5
VHF decoder
75
50
112.5
Interface to PC
20
50
30
Launch Campaign
450
50
675
SPOT (Meteolabor)
50
50
75
Facilities
250
50
375
Vehicles for recovery
150
50
225
Global Shipping Cost
100
50
150
TOTAL COST
1846
34
2466
%
38.4
24.1
0.0
1.5
0.6
12.2
3.0
2.4
0.0
0.6
2.3
0.6
1.6
18.6
2.2
2.7
2.2
0.5
1.1
1.1
0.0
2.4
3.0
1.5
1.6
10.3
4.6
4.6
1.2
27.4
3.0
15.2
9.1
6.1
Table 5.6: SHAGARE – Cost Budget for the meteorological balloon – this budget is restricted as the
payload costs are not shown here.
page 40 of 67
Issue 1
Bibliography
Peer-reviewed Articles and Books
[1] Baird-Atomic Inc., Scintillation Spectrometry, Cambridge, Mass.
[2] G. F. Knoll Radiation Detection and Measurement, John Wiley & Sons, 1999.
[3] Siegl. M, BEXUS User Manual, Issue v6.3, 31 Aug 2011
[4] M. J. Weber, R. R. Monchamp Luminescence of Bi4 Ge3 O1 2: Spectral and decay properties, Journal of Applied
Physics 44, 5495, 1973.
[5] G. Roper Yearwood, SED (Student Experiment Documentation) PERDaix, 5May 2010
Data Sheets
[6] Hamamatsu: Characteristics and use of Si APD (Avalanche Photodiodes), [online]: http://sales.hamamatsu.
com/assets/applications/.
[7] Hamamatsu: MPPC Multi-Pixel Photon Counter, [online]:
products/ssd/pdf/tech/mppc_selection_guide_e.pdf.
http://jp.hamamatsu.com/resources/
[8] Meteolabor: Preisliste, Wetterballone für Privaten gebrauch, October 2012
Websites
[9] Arduino Website, http://www.arduino.cc/
[10] Arduino
Pin
Current
ArduinoPinCurrentLimitations
Limitations,
http://www.arduino.cc/playground/Main/
[11] Bexus/Rexus Website, http://www.rexusbexus.net/
[12] PERDaix Website, http://www.perdaix.de/
[13] GGES Website, http://gges.epfl.ch/
[14] Sparkfun Electronics Website, https://www.sparkfun.com/
[15] Trackuino Website, http://code.google.com/p/trackuino/
[16] Wyoming University, Balloon Trajectory Forecast, http://weather.uwyo.edu/polar/balloon_traj.html
Course Documentation
[17] M. Ribordy, Introduction à la physique des astroparticules, 2008
page 41 of 67
Issue 1
Appendices
page 42 of 67
Appendix
Issue 1
A
BEXUS Proposal
page 43 of 67
Issue 1
REXUS/BEXUS
EXPERIMENT PROPOSAL FORM.
Your text should be intelligible to scientists of various fields and engineers with a general scientific
background.
Before you submit your proposal, please ensure that you have read the REXUS/BEXUS
Technical Overviews. You can also refer to the REXUS/BEXUS User Manuals for more
detailed information. The forms and the documents are available at www.rexusbexus.net.
To submit your proposal to DLR, please sent the Letter of Intent for registration and the filled-in
application form electronically before their deadlines to rexusbexus@dlr.de
Team/Short experiment name
E.g. the acronym of the full experiment title
HAGARE
Full experiment title
High Altitude Gamma-Rays Experiment
REXUS
BEXUS
spinning with 4 Hz
despun with Yo-Yo to about 0.08 Hz
Science & Organisation
Team Information
Student team leader:
Include name, university, field of study, graduate/undergraduate, academic year,
and any additional team roles of the team leader if applicable.
(This section should be completed)
Contact information
of team leader:
Include at least the phone number, email address and postal address.
Members of your team:
Include name, university, field of studies, graduate/undergraduate, academic year,
and expected team roles.
Page 1 of 15
page 44 of 67
Issue 1
REXUS/BEXUS EXPERIMENT PROPOSAL FORM
What is the scientific and
/ or technical objective of
your experiment?
This description should outline the scientific / technical question addressed, the
assumptions made and the research methods chosen to solve the question.
Expected results should be stated.
(This section should be expanded once HAGARE will have
been completely defined by the LPHE to give a more in depth
insight.)
Scientific objectives :
1. To determine the rate of gamma cosmic rays at high altitude
for a relatively simple design for the detector in the range of
energy 50-2000 keV. The rate of gamma-rays varies with
the altitude as their mean free paths diminish with
decreasing height due to the atmosphere.
2. To characterise the gamma-rays detected by means of their
energy and their origin in the sky.
3. To prepare a long term large suborbital balloon-borne
experiment.
Technical objectives :
1. To design, build and validate a small and simple high
altitude gamma-rays detector.
2. To achieve the second scientific objective, the attitude of the
experiment must be recorded at all time during the flight
with a precision of at least 3 degrees.
3. The efficiency of the detector varies with the temperature
and therefore, an active thermal subsystem will be designed
such that the operating temperature range of the detector is
respected.
4. To store efficiency and robustly the data.
Page 2 of 15
page 45 of 67
Issue 1
Why do you need a
rocket / a balloon?
If you need a rocket:
- Does your experiment require a reduced gravity environment?
- What is the necessary duration of the phenomenon? (maximum 90 seconds of
reduced gravity might be available)
If you need a balloon:
- What is the optimal altitude for your experiment?
- Does your experiment require daylight, for what duration/part of the flight?
If part of the flight should be in the night/dawn/dusk/please also state this.
The measurements of the gamma-rays part of the cosmic rays
depend greatly on the altitude at which the detector is located. With
increasing altitude, the atmosphere thins and thus the number of
cosmic gamma-rays not absorbed by it, increases. The attenuation
of the flux of gamma-rays photons was studied in the preliminary
phase of this project. This clearly shows (Figure 1) that at low
altitudes there is no flux, which is a good fact for life on Earth, but
not for the study of high energy cosmic rays.
Figure 1: Proportion of γ-rays photons at different energies received by
the detector relative to the photons received at 32 km above ground at a
zenith angle of 10°.
Since the absorption is minimal for altitudes lower than 15 km, the
need for the experiment to be at this high altitude developed. Air
planes fly below this minimum altitude, typically at 10-15 km.
Moreover, the gamma rays flux in the range of energy considered is
low which demands a long time at this altitude. A balloon-borne
experiment provides good conditions for the measurements with an
optimal altitude of about 35 km.
The time at which the experiment would fly is not too important to
us. Of course if the balloon flies during dusk or the night, the Sun
which is a source of error would not be present and the
measurements easier. But if the data analysis can be adapted if the
balloon was to flight during the day.
If the results are conclusive, the experiment could be repeated at a
larger scale, just as the PERDaiX experiment was an inspiration for
the now ongoing PEBS experiment.
Page 3 of 15
page 46 of 67
Issue 1
Where did you get the
idea from?
E.g. research programme at your university, already performed similar experiment,
scientific publications, books, etc.
In 2010, a collaboration between RWTH Aachen University and
Ecole Polytechnique Fédérale de Lausanne (EPFL) resulted in the
PERDaiX experiment also flown with the BEXUS program.
This success led to the PEBS project that has essentially the same
objective as PERDaiX and which will fly over the north pole, during
almost 40 days.
On the PERDaiX experiment, the contribution of the EPFL was
mainly in the Particles Physics field. With the development and
growth of the Swiss Space Center, the idea of a collaboration
between the Laboratory for High Energy Physics (LPHE) and the
Swiss Space Center was brought up to realise this experiment.
The EPFL has also participated in another experiment on REXUS:
Gravity Gradient Earth Sensor (GGES) which was developed by
people involved with the Swiss Space Center.
Page 4 of 15
page 47 of 67
Issue 1
Describe your experiment
This part should link the scientific objective to the experiment itself. Explain how
you are going to fulfil the scientific goal.
HAGARE will be made of several dozen of small detectors – crystal
scintillator and a photomultiplier – that each creates one channel.
Those channels will detect gamma-rays (see below) and create an
“event”. The signal goes through a trigger that verifies that the
energy detected represents a particle and not noise. This event is
then stored in a data storage unit. The different channels have their
own orientation and therefore yield a direction towards the origin of
the photon.
Crystal Scintillator. In the detector, gamma-rays first scintillate in
an inorganic crystal by interacting with an electron. In the range of
energies being probed in this project (approximately 50-2000 keV),
gamma-rays mostly interact through three distinct ways :

Firstly, the gamma photon can be photoelectrically absorbed
by an orbital electron. This electron acquires a kinetic
energy Ek=ħω - Eb where Eb is the electron binding energy
and ω is the pulsation of the photon. This case is the most
interesting because the full energy of the gamma is
absorbed by the electron.

The second way is Compton scattering, where the photon
elastically scatters an electron. In this case, the kinetic
energy of the recoil electron strongly depends on the
scattering angle. It can easily be proven that the kinetic
energy of the recoil electron lies between 0 and a maximal
value which is always strictly lower than the full energy of
the photon.

Lastly, if ħω ≤ 2mec2 where me is the electron mass, the
photon travelling in the vicinity of an atomic nucleus can
produce an electron and an anti-electron pair, the energy of
each of which is given by Ee = ½ħω – mec2
In these processes, the excited electrons can disperse their energy
in various different ways, e.g. thermally or by emitting lower energy
photons. The last possibility is the most interesting for gamma
detection. This scintillation process can occur in various ways
depending on the crystal used. In the case of bismuth germanium
oxide (BGO), whose performances have been measured, the
electron disperses its energy by interacting with bismuth ions,
which relax emitting photons in the visible spectrum. In the case of
another crystal which has been studied,
thallium doped sodium
iodide (NaI(Tl)), the de-excitation process occurs in a the vicinity of
a thallium impurity, where the energy levels are closer to each
other, also emitting visible photons.
Once scintillation photons are emitted, they reflect on the crystal
coating (typically made of teflon) before being converted into an
electrical current in an silicon photomultiplier (SiPM), whose
operating principle in described in the following section.
Page 5 of 15
page 48 of 67
Issue 1
Silicon Photomultiplier. A silicon photomultiplier is a device
designed to count a number of photons. It is made of an array of
avalanche photodiodes, connected in series with a resistor. An
avalanche photodiode operates in Geiger mode, that is to say that
the bias voltage applied to the diode is higher than the breakdown
voltage, which means that any photon entering the diode produces
a breakdown current which is stopped only when the voltage drop
in the resistor will be sufficiently large. Such a diode is sketched on
figure (Figure 2). Hence, an avalanche photodiode gives a signal
which is independent on the energy of the incoming photon.
Therefore, when submitted to a flash a photons, a SiPM gives a
currant pulse which is proportional to the number of incoming
photons. One of the advantages of this device is that the avalanche
mechanism acts like a current amplifier.
+
+
Figure 2: This figure depicts an avalanche photodiode. The n and p
layers respectively represent the regions which are highly doped in donors
or acceptors. An incoming photon will excite an electron-hole
pair in the
+
+
middle depletion region. The electron then drifts to the n and p layers
where the electric field is so high that the electron generates an avalanche
of new electron-hole pairs.
Page 6 of 15
page 49 of 67
Issue 1
Which data do you want to
measure?
The photons that hit the detector, which is made of several SiPM
are measured in terms of their energy. The different signals or
channels are then read-out by a trigger which decides whether an
event is a real one or is to be rejected because it is noise. This
process is done continuously with a number of channels equal to
the number of scintillators implemented. The trigger will allow
strong enough signal in the energy range of 50 keV – 2 MeV to be
processed.
Moreover, as an event originates from at least one of the SiPM, the
field of view can be meshed in the number of channels that the
experiment has. To find the source of the event in the sky, the angle
of the detector with some reference direction must be measured.
Hence, a magnetometer coupled to an accelerometer provides the
information required to produce an azimuth with respect to the
magnetic North. In the post processing of the data, the azimuth is
then used both to subtract the spin of the balloon and to reconstruct
a map of the events recorded in the field of view. Those
measurements must be done often to compensate for an eventual
mid to high spin rate of the balloon as well as to provide sufficient
precision of in the direction to reconstruct the azimuth properly. The
proposed sampling frequency of the azimuth of the detector is at
least 5 Hz. A sensor measures the altitude of the balloon in order to
characterise the event better as well as providing complementary
position information.
Moreover, to characterise better the type of photon that hit the
detector and being able to apply an altitude threshold on the data
measurement and an insight into the dynamics of the flight, a global
navigation satellite system receiver is implemented. As the ascent
and descent rate are maximum 10 m/s and that the approximate
vertical precision is 5 meters, a sampling frequency of 2 Hz is
enough.
In addition, the service module generates housekeeping
information every 30 seconds. This package contains the
temperature at several points of the experiment as well as outside,
the voltage of the batteries and the current consumed by the
experiment.
Page 7 of 15
page 50 of 67
Issue 1
How do you want to take
measurements?
The detector itself is in shape of a dome oriented up with respect to
the balloon vertical. The dome would consist of about a hundred of
SiPM separated by a few degrees. Moreover, the dome would be
protected with a shield that would prevent charged particles to
reach the detectors.
Figure 3: Sketch of the detector. The number of scintillators is thought to
be about 100.
The scientific data as well as the azimuth and the housekeeping
data are then stored on a mass storage device, probably several
flash cards. Some data will then be transmitted to the ground: the
housekeeping package as well as some of the photon events with
their azimuth and their scintillator of origin. The processing unit has
to choose some of the event to downlink. All events will be
recorded on the solid state memory if possible in a redundant way
such that we can still recover the data in case of part failure of the
mass memory unit.
Describe the process flow
of your experiment.




What do you plan to do with
your data after the flight?
Before launch : HAGARE initialisation
From launch onwards: continuous measurement, triggering
and storage. In parallel: measurements of different
housekeeping parameters.
Downlink of the data every two minutes for redundancy
reasons.
At landing: using data from the altitude determination
subsystem, the central processing unit shuts the experiment
down.
The data will after the flight by methods developed in parallel of the
development of HAGARE. Those methods are based upon a
pathfinder experiment launched on a meteorological balloon.
Firstly, the data will be post-processed on ground to correlate the
attitude of the experiment with and the altitude with the data. This
will enable us to create a sky map of our data as well as performing
the first analysis of the rates of altitude in function of the altitude.
Secondly, detailed analysis of the data will be performed for some
of the most interesting events and in the process, the efficiency of
the detector will also compared with the model that will have been
established before the flight.
Finally, the opportunity of developing a much larger version of
HAGARE for a long flight over the Arctic (much like in the PERDaix
experiment) will be assessed.
This work will carried out in the form of semester and master
projects and most certainly in the form of a doctoral study.
Page 8 of 15
page 51 of 67
Issue 1
Organisation of your
project
How will you organize / distribute work within your team? Please note that you are
responsible for all aspects of your experiment (science, mechanical & electrical
engineering, software, etc.)
Are you supported by
institutes and/or senior
scientists?
Do you have access to a
workshop or a laboratory
that meets the fabrication
and testing needs of your
experiment?
If yes, please indicate the name of the institute(s) and/or senior scientist(s).
The project is a collaboration between the Swiss Space Center
(SSC) and the Laboratory for High Energy Physics Laboratory
(LPHE), both from Ecole Polytechnique Fédérale de Lausanne
(EPFL) :

Dr. Anton Ivanov for the Swiss Space Center (SSC)

Prof. Aurélio Bay for the High Energy Physics Laboratory
(LPHE).
We intend to develop the HAGARE project at EPFL. As the two
main laboratories involved have access to clean rooms, mechanical
and electronics workshops. All those facilities are on the campus of
the EPFL.
Concerning the testing, we can use facilities at and close to EPFL
that were used in the validation process of the cubesat Swisscube
and the currently in development cubETH.
Both laboratories have experience with developing and testing
complex devices that were used in particle physics for LPHE and in
space and near for the SSC. We can also benefit from the
experience of the people that worked in past heritage or current
projects.
Do you have all the
material and equipment
which is needed for your
experiment? If not, how do
you plan to obtain it?
Most of the equipment needed to build HAGARE has to be
developed based upon past experiments such as PERDaix which
was an Aachen University / EPFL project to measure high energetic
cosmic particle fluxes and the solar modulation of charged cosmic
rays.
The dome with the trigger will be designed and developed by the
LPHE and the SSC will be responsible for the development of the
other subsystems.
The detector and the trigger will completely be designed and
produced at EPFL while other parts such that magnetometers or
batteries will be off-the-shelf components.
How do you plan to finance
your expenses?
We will get support from EPFL and particularly thanks to the
internal Teaching Bridge Project.
Who else will support you
(sponsors, others)?
We will try to get support from different companies from which we
use components (such as u-blox for the altitude determination).
Outreach Programme
Describe your outreach
programme for before,
during and after the
REXUS/BEXUS flight
campaign.
How are you planning to present your experiment to the public? E.g. newspaper,
local radio, webpage, presentation at the university, etc.
The execution of an outreach programme is mandatory!
The outreach program will be composed of :
Page 9 of 15
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Issue 1

A website in English and French describing the experiment
and documenting the progress of the project with
information both for the general public and experts.

At least one article in the Flash-EPFL the newspaper of
EPFL.

Presentations for the different laboratories involved in the
project as well as public talks in the framework of the
different outreach programs of the SSC and LPHE.
Page 10 of 15
page 53 of 67
Issue 1
Experimental Set-up & Technical Information
Mechanics
Describe your experimental
set-up.
Describe and outline the preliminary set-up of your experiment. Include a least a
sketch or block diagram of the experiment (CAD drawings are optional).
Figure 4: Functional block diagram representing the different HAGARE
subsystems as well as the sampling frequencies.

About 100 SiPM on a dome-shaped support separated by
lead shielding covered with a foil.

A trigger to filter the signals of the channels.

Analog-to-digital converter and amplifier for the measured
signals.

One magnetometer compensated for tilt in order to
determine the localisation of an event in the sky.

A GPS receiver with an antenna to determine the altitude
and characterise better the different events.

At least four temperature sensors (detector, trigger, central
processing unit and batteries).

At least two voltmeters (detector, batteries) and two
ammeters.

Flash memory for data acquisition.

Batteries.

Mechanical interface to BEXUS.

Optional heaters close to the detector if found necessary.
Page 11 of 15
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Issue 1
Estimate the dimensions
and the mass of your
experiment (kg and m).
Dome: about 250 x 250 x 250 mm
The dome is embedded in a box of 400 x 400 x 600 mm with all the
electronics and batteries contained.
Mass: about 40 kg.
Indicate the preferred
position of your experiment:
REXUS:
Indicate the orientation of your experiment and the preferred position in the rocket: module or
nosecone section. Do you need access to the outside environment? Holes? Hatches?
BEXUS:
Define preferred position in the gondola, inside units, external units? Do you need access to
the outside environment?
Side view of a gondola
Top view of a gondola with mounting rails
The dome should not be preferably covered by other experiences
to avoid blocking the gamma-rays.
Electrics / Electronics
Will you need the 28 Vdc
power supply from the
REXUS service system or
power from the BEXUS
gondola respectively?
No, we will use ours.
Will you need (additional)
batteries? What do you
need for charging?
Qualified batteries are listed in the REXUS and BEXUS User Manuals.
Estimate the electrical
consumption of your
experiment (Ah or Wh).
Max. 50 W × 8 hours = 400 Wh.
Do you use any equipment
with high inrush currents? If
E.g. Motors may need high inrush currents which exceed the nominal allowed
current limit.
We will use our own power source.
Page 12 of 15
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Issue 1
so estimate the current (A).
No.
Do you need auxiliary
power? Do you need a
separate umbilical?
Auxiliary power for charging or consumption before launch is not standard.
Mention here whether you need auxiliary power and why.
Use of uplink and downlink:
Please indicate expected data rates for uplink and downlink.
No.
Please note: In addition to on-board storage, it is mandatory that you downlink
housekeeping/scientific data during flight.
On BEXUS, an uplink is also available throughout the flight. On REXUS, an uplink
is not normally available during flight but should be used during ground testing.
Downlink: 8 Mb packets every 2 minutes.
Uplink: a maximum of 400 kb packet every 2 minutes would be
used to to pass commands if judged necessary.
REXUS Only: Do you need
to use the REXUS TV
Channel?
There is only one TV channel available, so only one experiment can use it at any
one time and a maximum of three experiments can be connected. Why should one
be your experiment?
Provide an event timeline,
including the experiment
actions during flight, such
as timer or telecommand
events.
Describe your event timeline.
1) Turn On and initialising
1.1) Turn computer On
1.2) Check Subsystems
1.3) Start communications
– LAUNCH –
2) Continuous data acquisition and sending
2.1) Send Data every 2 min
2.2) Send housekeeping Data every 2 min
3) When the termination flight command occur :
1. Stop data acquisition
2. Enter power save mode
– DESCENT –
4) Landing : go into sleep mode
4.1) Stop Data acquisition
4.2) Stop Household Data acquisition
4.3) Stop communications
4.4) Turn computer off
Environmental Questions
& Safety Issues
Does the experiment use
wireless devices?
E.g. Wifi (WLAN), Bluetooth, infrared, airport, data transmitters. Describe the type
of devices and frequencies used.
No.
Page 13 of 15
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Issue 1
Does the experiment create
any disturbing magnetic or
electrical fields?
No, apart the small perturbations created by the electronics.
Do you expect to use high
voltages in any part of your
experiment?
Please indicate the voltage and its use within the experiment and any expected protection
devices.
Does your experiment eject
anything from the rocket?
Please note that ejections from the BEXUS balloons are not available.
No.
-
Is the experiment sensitive
to light?
No.
Is the experiment sensitive
to vibrations?
No.
Does the experiment
generate vibrations?
e.g. Vacuum pump, rotating devices, etc.
No.
Will you use any
flammable, explosive,
radioactive, corrosive,
magnetic or organic
products?
Specify any products you will use with any of these characteristics.
Will you use a laser?
Which class? Is the laser path securely contained?
No.
No.
Is your experiment airtight?
Are parts of your
experiment airtight?
Yields to a pressurized experiment (1 bar) when the vehicle reaches higher
altitude with lower pressure values.
This question should remind you that there will be a very low ambient pressure
environment for your experiment.
No apart from the data storage unit.
Are there any hot parts (>
60°C)?
Mention any parts besides electronics that heat up.
Are there any moving
parts? Are the moving parts
reachable?
This is important for the preparation before launch. Access to the experiment will
be discussed with EuroLaunch. E.g. a tappet is used for a moving part.
Do you need any pressure
systems from Eurolaunch
before launch?
No.
No.
If you know that you need for example a pressurized nitrogen-bottle for your
experiment before launch, please mention it here. All pressurized bottles will be
handled by EuroLaunch personnel.
No.
Page 14 of 15
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Issue 1
Is there any aspect in your
experiment which you
believe may be viewed as a
safety risk by others
(regardless of whether you
will mitigate this risk in your
design)?
No.
Page 15 of 15
page 58 of 67
Appendix
Issue 1
B
Contact List
Name
Prof. Bay, A.
Belloni, F.
Organisation
EPFL/LPHE
EPFL/SSC
Email
aurelio.bay@epfl.ch
federico.belloni@epfl.ch
Prof. Beuchat, R.
EPFL/LAP
rene.beuchat@epfl.ch
Dr. Bruijn, R.
EPFL/LPHE
ronald.bruijn@epfl.ch
Dr. Clerc, J.-M.
MétéoSuisse
Jean-Michel.Clerc@meteoswiss.ch
Dr. Greim, G.
Aachen
greim@physik.rwth-aachen.de
Dr. Haefli, G.
EPFL/LPHE
guido.haefeli@epfl.ch
Humair, T.
EPFL/LPHE
thibaud.humair@epfl.ch
Dr Ivanov, A.
Kuntzer, T.
EPFL/SSC
EPFL/SSC
anton.ivanov@epfl.ch
thibault.kuntzer@epfl.ch
Dr Maag, R.
Meteolabor
Rolf.Maag@meteolabor.ch
Van Scherven, E.
EPFL/SSC
eleonie.vanschreven@epfl.ch
Description
LPHE leading professor
System engineer who reviewed the
modified Trackuino board.
Processor Architecture Laboratory
leading professor who is interested
to get his laboratory involved in the
project.
Scientist at LPHE who is supervising the detectors investigations.
Head of Radiosounding and Atmospheric Data at Payerne for Météo
Suisse. He launched many balloons
in his career. Offered to meet with
him to discuss the procedures ; we
replied that we were still designing
SHAGARE.
Responsible for the PERDaix
project, http://www.perdaix.de.
Scientist at LPHE who is supervising the data acquisition.
Master student involved in the detectors.
Supervisor of the project in SSC
Master student involved in system
engineering for the project.
Meteolabor is the provider of balloons for Météo Suisse.
He is
the head of the meteorological
balloons department, http://www.
meteolabor.ch/ and offered to lend
us the SPOT device for SHAGARE.
Master student involved in system
engineering for the project.
page 59 of 67
Appendix
Issue 1
C
SHAGARE Avionics Schematics
C.1
Boards Layouts
Figure C.1: SHAGARE Avionics Schematics – Board layout of the modified Trackuino shield – top of the board
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Issue 1
Figure C.2: SHAGARE Avionics Schematics – Board layout of the modified Trackuino shield – bottom of the board
page 61 of 67
Issue 1
Figure C.3: SHAGARE Avionics Schematics – Board Layout of the microSD shield/Data Storage Unit
page 62 of 67
Issue 1
Figure C.4: SHAGARE Avionics Schematics – Board Layout of the Arduino Uno Board/Data Storage Unit
page 63 of 67
C.2
Issue 1
Schematics
Figure C.5: SHAGARE Avionics Schematics – Schematics of the Trackuino schield
page 64 of 67
Issue 1
Figure C.6: SHAGARE Avionics Schematics – Schematics of the microSD shield
page 65 of 67
Issue 1
Figure C.7: SHAGARE Avionics Schematics – Schematics of the Arduino Uno Board
page 66 of 67
C.3
Issue 1
List of Components
Table C.1: SHAGARE Avionics – List of the needed components and their prices.
page 67 of 67
Appendix
Issue 1
D
Example of a Trade-off
Criteria
Dedicated FPGA
Trackuino
Importance in %
ALTERNATIVES
I
M
IM/10
M
IM/10
Robustness
18
5
8.9
10
17.8
17
0
0.0
5
8.3
Development Time
20
10
20.0
0
0.0
Simplicity
22
10
22.2
5
11.1
Accessibility
16
5
7.8
5
7.8
8
10
7.8
0
0.0
Cost
SCORE
66.7
45.0
RANK
1
2
Table D.1: Example of trade-off using Tab. 5.2 for the evaluation criteria. 10 is the best mark and 0 the
worst.
page 68 of 67

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