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THE THE AVENGERSAVENGERSMeasuring Atmospheric OzoneMeasuring Atmospheric Ozone
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GeneralGeneral
• The primary goal of the ITO sensor project is to measure the concentration of Ozone (O3) as a function of altitude.
• The concentration of these gases will specify the current situation of ozone depletion.
• These measurements will be compared to past measurements made by other payloads.
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ScienceScience
• The measurement from the sensor is done as the function of physical quantities as the sensor might function in a different way depending on the altitude, temperature, humidity and pressure.
• The obtained measurements are compared with various experiments showing the precise concentration of Ozone.
• Different halogens, such as Flourine, Chlorine, and Iodine have been used to accelerate this process.
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TechnicalTechnical
• The concentration of Ozone is calculated as the function of voltage produced across the sensor.
• As the resistance in the ITO sensor varies with the concentration of these gases, different voltages are produced with the same amount of input current in the circuit board.
• The Real Time Clock will be utilized as a counter and a timestamp will be printed for each measurement so that it can be related by time to altitude.
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System DesignSystem Design
BalloonSatEEPROM
ITO Sensor ITO SensorITO SensorITO Sensor
BasicStampEEPROM
ADC Channels
CH0 CH3CH2CH1
8 bit data0 - 3V
8 bit data0 - 3V
8 bit data0 - 3V
8 bit data0 - 3V
12V SupplyBalloonSAT 5Vconstant voltage
supply
12 V
Current Sources
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Electrical Design and Electrical Design and DevelopmentDevelopment
Sensors/Sensor InterfacingSensors/Sensor InterfacingControl ElectronicsControl Electronics
Power SupplyPower SupplyPower BudgetPower Budget
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Sensors/Sensor InterfacingSensors/Sensor Interfacing
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Control ElectronicsControl ElectronicsBalloonSATBalloonSAT
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Nichrome HeaterNichrome Heater
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Power SupplyPower Supply8 x L91, AA,12V Supply
4 x L91, AA,6V Supply
CR2032,3V Supply
<450nAReal-Time
Clock
2.5 WNichrome
Heater
BalloonSAT53 mA
5V ConstantVoltage Supply,
BalloonSAT
ITO 1
ITO 2
~ 1
mA
NTC Thermistor,Comparator
Circuit inputs.
ITO 4
ITO 3
30
mA
Z740-ND RelayCoil
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Power BudgetPower Budget
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Software DesignSoftware Design
Data Format and StorageData Format and Storage
Flight SoftwareFlight Software
Software Development PlanSoftware Development Plan
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Data Format and StorageData Format and Storage
• BalloonSat EEPROM will store all data collected on flight (Yellow Circle)
• BasicStamp EEPROM stores addresses for flight software (Red Circle)
Byte # Data Stored0 Original Address1 Current Address
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Flight SoftwareFlight Software
• Read “original address” from BasicStamp EEPROM
• Add counter to data – 1 byte
• Read RTC – 3 bytes
• Read all 4 ITO sensors– 4 bytes
• Store all data from reading • Store current address in
BasicStamp EEPROM• Repeat loop until current
address equals the original address– (current_address =
original_address)– LED flashes once per second
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Software Development PlanSoftware Development Plan• Prototyping Software
– Software must run without glitches– Software must successfully record
correct data from input sensors• Data must be saved in a way
that it will not be overwritten– Once software is completely
functional, it will be optimized– Software will be uploaded to
Excel, so it must be formatted• Prototyping Hardware
– Electronics and Mechanical aspects should work with software
– Temperature and Pressure Tests• Flowcharts
– As the code is written and refined, flowcharts will be updated
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Thermal DesignThermal Design
• ITO Sensors must maintain temperatures between 24 and 30 degrees Celsius
• Nichrome wire @ 22.3 ohms/m
• Requires approximately 2.5W
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Mechanical DesignMechanical Design•A hollow regular hexagonal A hollow regular hexagonal prismprism
•FOAMULAR Insulating FOAMULAR Insulating SheathingSheathing
External Design:External Design:•Each side of the base = 94 Each side of the base = 94 mmmm
•The height of the prism = 193 The height of the prism = 193 mmmm
•51mm X 49mm rectangular 51mm X 49mm rectangular hole for the ITO sensorhole for the ITO sensor
•The ITO sensor attached The ITO sensor attached from the inner walls; minimal from the inner walls; minimal area of the ITO sensor is area of the ITO sensor is exposedexposed
The external design of ITO sensor payload (in m) 17 of 25
Internal Design:
• Rectangular- shaped foam (thickness = 18 mm) bisects the internal payload in two
– Batteries, ITO sensor and Nichrome heater
– BalloonSAT
• Two chambers have different temperatures
• Nichrome wire attached to the back of the sensor with thermal paste
Internal Divider with BalloonSAT (in m)
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a) Side where ITO sensor is attached (in m)
b) Side where ITO sensor is attached with ITO sensor (in m)
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Weight Budget:
• Balloon payload should be less that 500 g
• Density of The FOAMULAR Insulating Sheathing = .029 g/ cm3
S.N.
Components Weight (gram) Clearance (g)
1. BalloonSAT 60.4 +/- 5
2. FOAMULAR Insulating Sheathing 115 +/- 20
3. Power Supply (Battery) 178.8 +/- 25
4. ITO sensor and PCB 6.1 +/- 2
5. Components for Sensor Interface 35* +/- 15
6.7.8.
Mass of cable for ITO sensorNichrome Wire and thermal pasteTape, Glue and other structure
173*
20*
+/- 3+/- 2+/-5
Total: 435.3 +/- 77* Approximated within 0.1g
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CalibrationsCalibrations
Calibration of Sensor#1 with Ozone
y = 0.137x + 1.3183
R2 = 0.9949
y = 0.0133x + 1.6001
R2 = 0.963
1.3000
1.4000
1.5000
1.6000
1.7000
1.8000
0.00 2.00 4.00 6.00 8.00 10.00
Concentration of Ozone (ppm)
Res
ista
nce
of
sen
sor
(KO
hm
s)
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Ground SoftwareGround Software
• Save into text file
• Use Microsoft Excel
• Algorithms pre-programmed
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Risk ManagementRisk Management
Software Malfunctioning
Malfunctioning of ITO sensor
User BacklashInterface Problem
Cold Solder Joint
Unexpected Weather
Group Conflit
Bad Component in the payload
System Freezing
Bad Landing (Not on ground)
Batteries DrainedHardware
Malfunctioning
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Looking AheadLooking Ahead
• Flight Readiness Review (FRR): 5/4/2010
• Liftoff! (Palestine): 5/25/2010
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Special ThanksSpecial Thanks
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