rocketsat v: aircore · • homosphere – 2 km to upper limit 80-100 km – wind currents...

Colorado Space Grant Consortium

RocketSat V

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RocketSat V

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RocketSat V: AirCore

4/18/09

Symposium

Jessica (JB) Brown

Mackenzie Miller

Emily Logan

Steven Ramm


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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.


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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


RocketSat V

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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


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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


RocketSat V

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RocketSat V

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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


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RocketSat V

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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


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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


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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


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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


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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


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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


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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


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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


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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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Balloon Flight Results


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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


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RocketSat V

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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


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RocketSat V

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Backup Slide: 3/8 inch Storage Test January 30

Coils

Mean: 408.3487 ppm

Tank

Mean: 408.2887 ppm

rocketsat v: aircore · • homosphere – 2 km to upper limit 80-100 km – wind currents...

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