Transcript Pre-CDR Presentation

THE
AVENGERS
Measuring Atmospheric Ozone
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General
• 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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Science
• 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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Technical
• 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 Design
BalloonSAT 5V
constant voltage
supply
12 V
5
V
12V Supply
Current Sources
1m
ITO Sensor
A
A
A
1m
1
mA
1m
ITO Sensor
8 bit data
0 - 3V
ITO Sensor
ITO Sensor
8 bit data
0 - 3V
8 bit data
0 - 3V
8 bit data
0 - 3V
CH0
CH1
CH2
CH3
ADC Channels
BalloonSat
EEPROM
BasicStamp
EEPROM
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Electrical Design and
Development
Sensors/Sensor Interfacing
Control Electronics
Power Supply
Power Budget
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Sensors/Sensor Interfacing
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Control Electronics
BalloonSAT
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Nichrome Heater
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Power Supply
8 x L91, AA,
12V Supply
ITO 1
1m
A
5V Constant
Voltage Supply,
BalloonSAT
1 mA
ITO 2
A
1m
ITO 3
1
30 mA
~ 1mA
NTC Thermistor,
Comparator
Circuit inputs.
BalloonSAT
53 mA
A
m
Z740-ND Relay
Coil
ITO 4
4 x L91, AA,
6V Supply
2.5 W
Nichrome
Heater
CR2032,
3V Supply
<450nA
Real-Time
Clock
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Power Budget
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Software Design
Data Format and Storage
Flight Software
Software Development Plan
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Data Format and Storage
• BalloonSat EEPROM will
store all data collected on
flight (Yellow Circle)
• BasicStamp EEPROM
stores addresses for
flight software (Red
Circle)
Byte #
0
1
Data Stored
Original Address
Current Address
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Flight 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 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 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 Design
•A hollow regular hexagonal
prism
•FOAMULAR Insulating
Sheathing
External Design:
•Each side of the base = 94
mm
•The height of the prism = 193
mm
•51mm X 49mm rectangular
hole for the ITO sensor
•The ITO sensor attached
from the inner walls; minimal
area of the ITO sensor is
exposed
The external design of ITO
sensor payload (in m)
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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 sensor
Nichrome Wire and thermal
paste
Tape, Glue and other structure
17
3*
20*
+/- 3
+/- 2
+/-5
435.3
+/- 77
* ApproximatedTotal:
within 0.1g
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Calibrations
Calibration of Sensor#1 with Ozone
Resistance of sensor
(KOhms)
1.8000
1.7000
y = 0.0133x + 1.6001
R2 = 0.963
1.6000
1.5000
1.4000
1.3000
0.00
y = 0.137x + 1.3183
R2 = 0.9949
2.00
4.00
6.00
8.00
10.00
Concentration of Ozone (ppm)
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Ground Software
• Save into text file
• Use Microsoft Excel
• Algorithms pre-programmed
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Risk Management
Software
Malfunctioning
Malfunctioning
of ITO sensor
Interface
Problem
User Backlash
Cold
Solder
Joint
Unexpected
Weather
Group
Conflit
Bad Component
in the payload
System
Freezing
Bad
Landing
(Not on
ground)
Batteries Drained
Hardware
Malfunctioning
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Looking Ahead
• Flight Readiness
Review (FRR):
5/4/2010
• Liftoff! (Palestine):
5/25/2010
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Special Thanks
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