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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