rocketsat v: aircore · • homosphere – 2 km to upper limit 80-100 km – wind currents...
TRANSCRIPT
Colorado Space Grant Consortium
RocketSat V
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Colorado Space Grant Consortium
RocketSat V
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RocketSat V: AirCore
4/18/09
Symposium
Jessica (JB) Brown
Mackenzie Miller
Emily Logan
Steven Ramm
Colorado Space Grant Consortium
RocketSat V
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Mission Statement
RocketSat V is a team of undergraduate
students working in collaboration with
NOAA to collect and validate an AirCore
sample with emphasis above 22 km to
determine the change in the concentration
of carbon dioxide and methane in the
upper atmosphere in order to create an
atmospheric profile.
Colorado Space Grant Consortium
RocketSat V
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History
• AirCore concept started
by NOAA
– Meant for Balloon flights
– Limited to ≈ 30 km
– Highest collected sample
with focus on CO2 36 km
•RocketSat IV
–Proved it could be flown on rocket
–Air contaminated by faulty pressure
sensor
Colorado Space Grant Consortium
RocketSat V
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Colorado Space Grant Consortium
RocketSat V
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Background: Rocket Payload
• RocketSat IV provided rocket flight heritage to AirCore concept
• Tubing coiled to fit into can
• Solenoid valve controlled by C&DH
• System collected sample successfully
• Contamination through pressure sensor
Colorado Space Grant Consortium
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Purpose
• Study greenhouse gasses
– Carbon Dioxide and Methane
• Very little data from above 22 km
– Complement previous high altitude measurements of
CO2 and CH4
– Extend AirCore concept beyond balloon flights
• Validate a collected sample of atmosphere
– Characterize stainless steel tubing
– Test flights alongside other methods of sampling
– Smaller temperature gradients experienced
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Colorado Space Grant Consortium
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Concept
• As altitude increases
CO2 and Methane
decrease
• Gasses take decades to
diffuse upwards
• Higher altitudes
contain “older” air
• Profile shows history
of atmospheric
concentration
Concentrations of CO2
Temperature
Colorado Space Grant Consortium
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Colorado Space Grant Consortium
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Concept: Payload
• Tubing starts at 280 Pa of known
gas and is closed until ~40 km on
descent
• Valve opens at one end between
42-38 km
– Within regime of viscous flow
• During descent, increasing
pressure outside pushes air into
tubing
• Location of air in tubing
corresponds to altitude
• Sample analyzed for carbon
dioxide and methane
Colorado Space Grant Consortium
RocketSat V
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Flight Altitudes
•Molecular flow above
~47 km
•Sampling from 40km
down to 6km
•Mean altitude of first
sample approximately
35km
•Most important
samples collected from
this flight: 40km down
to 15km
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Variation of Concentration
• Planetary Boundary Layer
– Surface to 2 km
– Drag from the surface of the earth causes turbulent wind currents
• Homosphere
– 2 km to upper limit 80-100 km
– Wind currents horizontally along isobars.
– Wind currents mix molecules, keep concentrations homogenous
– Changes in concentration due to diffusion, not mass
• Heterosphere– Lower limit at 80-100 km
– Wind currents are negligible
– Atmospheric gases are separated by molecular mass
– Concentrations of the lightest gases are the farthest up
Colorado Space Grant Consortium
RocketSat V
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Colorado Space Grant Consortium
RocketSat V
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Diffusion
• Molecular motion
causes displacement of
molecules
• Diffusion time related
to square of distance
• Longer tubing reduces
effect of diffusion on
sample resolution
DTXrms 2=Elapsed time X
rms
30ms 1mm
9 hrs 1 m
24 hrs 1.633m
9 days 5 m
2.5 years 50 m
Colorado Space Grant Consortium
RocketSat V
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Colorado Space Grant Consortium
RocketSat V
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Viscosity (ηηηη)
• Resistance of a fluid to shear stress
• Independent of pressure (Ρ)
• Not enough pressure differential at high
altitude
• Flow (Q) related to fourth power of diameter (w)
• Inversely related to length of tube (Ä )
• Viscosity increases as temperature increases
• Flow rate might not be sufficient to fill
tubing at high altitudes with high speed
descent
( )Pl
dQ ∆=
η
ρπ
128
4
Colorado Space Grant Consortium
RocketSat V
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Velocity
• Flow rate is a function of altitude
• Rocket will fall quickly through high altitudes
• Flow rate will not fill tubing with as many high
altitude samples
Colorado Space Grant Consortium
RocketSat V
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Tubing Effects
• Tubing needs to be clean
– Calcium carbonate and other contaminants
• Stainless steel wall effects
– Tubing absorbs gas molecules
– Lower pressure amplifies wall effects
• Water in tubing
– Water absorbs carbon dioxide and competes for
wall space
Colorado Space Grant Consortium
RocketSat V
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Tubing
Static
Port
Safety
solenoid
3/8” to 1/4”
Quick
Connect24 inches of 3/8”
drop down tubing
Pressure
Sensor
3/8” to 1/8”
connection
1/8” solenoid
valve
3/8” tubing 1/8” tubing
3/8” to 1/8”
connection
1/8” Hand turn ball
valve
Skin of Rocket
Pressure
Sensor
Colorado Space Grant Consortium
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Colorado Space Grant Consortium
RocketSat V
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Structure
• Tubing
– 3/8” tubing and 1/8” tubing
– Two separate coils bent to fit
inside canister
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Structure
• Flight Canister
– Height of 9.5”, a diameter of 9.75”
– All components of the payload must remain with in these dimensions
– All subsystems housed inside canister
Flight Canister
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Structure
• C&DH Stack– Four Makrolon plates stacked on top of each
other
– Bottom three each house different C&DH component
– Top plate serves as protection
Top plate with Air Core board,
z-accelerometer, and g-switch
Second plate with AVR board
Bottom plate with batteries
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Electronics
• Hardware
– Two main boards:
• AVR
– microprocessor of the system
– Software will be executed on the Atmega-32PU
– Accelerometers XYZ axis with high and low ranges
• Aircore
– external A/D converters (AD974)
– solenoid control circuit (N-channel MOSFET with Parker Solenoid)
– Pressure sensors
– Temperature Sensors
Colorado Space Grant Consortium
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Expected Results
• Previous NOAA
balloon flight
results show
concentrations of
CO2 and methane
decrease with
altitude
Concentrations of CO2
Temperature
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RocketSat V
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Balloon Flight Results
Colorado Space Grant Consortium
RocketSat V
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Testing
• Expected that sample will be offset due to tubing effects
• Try to characterize tubing effects and apply to flight sample– Solenoid Valve and Pressure Sensor
– Flow Test
– Storage Effects
– Slug Test
– Low Pressure Fill Test
– Gas Switch Test
– Temperature Fluctuation Test
– Full Mission Simulation Test
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Testing: Flow Test
• Run a calibrated gas through tubing
– Measure difference in parts per million of CO2
– Characterize inconsistencies due to wall
absorption
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Tank calibrated to 392.56 ppm
Flow Test 3-13
Average Coil reading:
392.57 ppm
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Testing: Storage Effects
• Flow known amount of gas into the tubing and
leave for 2 days and 3 days
• Measure offset from known gas concentration
• Know how much gas is absorbed by walls of
tubing
• Determine effect of storage time
Colorado Space Grant Consortium
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Colorado Space Grant Consortium
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3/8 inch Slug Test January 30
1-28 Slug Fill 1-30 Slug Fill After 2 day Storage
Time= 44 sec
Distance= 287.09 cm
Time= 41 sec
Distance= 267.51 cm
Time= 138 sec
Distance= 900.43 cm
Time= 140 sec
Distance= 913.48 cm
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Any Questions?
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Backup Slide: Storage test retrieval 3/16
Colorado Space Grant Consortium
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Colorado Space Grant Consortium
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Backup Slide: 3/8 inch Storage Test January 30
Coils
Mean: 408.3487 ppm
Tank
Mean: 408.2887 ppm