RocketSat V: AirCore. 4/18/09 Symposium Jessica (JB) Brown Mackenzie Miller Emily Logan Steven Ramm. Colorado Space Grant Consortium RocketSat V 1

Transcription

1 : AirCore 4/18/09 Symposium Jessica (JB) Brown Mackenzie Miller Emily Logan Steven Ramm 1

2 Mission Statement 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. 2

3 History AirCore concept started by NOAA Meant for Balloon flights Limited to 30 km Highest collected sample with focus on CO 2 36 km RocketSat IV Proved it could be flown on rocket Air contaminated by faulty pressure sensor 3

4 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 4

5 Purpose Study greenhouse gasses Carbon Dioxide and Methane Very little data from above 22 km Complement previous high altitude measurements of CO 2 and CH 4 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 5

6 Concept As altitude increases CO 2 and Methane decrease Gasses take decades to diffuse upwards Higher altitudes contain older air Profile shows history of atmospheric concentration Concentrations of CO2 Temperature 6

7 Concept: Payload Tubing starts at 280 Pa of known gas and is closed until ~40 km on descent Valve opens at one end between 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 7

8 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 8

9 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 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 km Wind currents are negligible Atmospheric gases are separated by molecular mass Concentrations of the lightest gases are the farthest up 9

10 Diffusion Molecular motion causes displacement of molecules Diffusion time related to square of distance Longer tubing reduces effect of diffusion on sample resolution Xrms = 2DT Elapsed time 30ms X rms 1mm 9 hrs 1 m 24 hrs 1.633m 9 days 5 m 2.5 years 50 m 10

11 Viscosity (η) 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 4 ρπd Q = 128η l ( P) 11

12 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 12

13 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 13

14 Tubing Pressure Sensor Pressure Sensor Skin of Rocket 3/8 to 1/8 connection 1/8 solenoid valve Safety solenoid Static Port 1/8 Hand turn ball valve 1/8 tubing 3/8 tubing 3/8 to 1/8 connection 24 inches of 3/8 drop down tubing 3/8 to 1/4 Quick Connect 14

15 Structure Tubing 3/8 tubing and 1/8 tubing Two separate coils bent to fit inside canister 15

16 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 16

17 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 17 Bottom plate with batteries

18 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 (Nchannel MOSFET with Parker Solenoid) Pressure sensors Temperature Sensors 18

19 Expected Results Previous NOAA balloon flight results show concentrations of CO 2 and methane decrease with altitude Concentrations of CO2 Temperature 19

20 Balloon Flight Results 20

21 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 21

22 Testing: Flow Test Run a calibrated gas through tubing Measure difference in parts per million of CO 2 Characterize inconsistencies due to wall absorption 22

23 Flow Test 3-13 Average Coil reading: ppm Tank calibrated to ppm 23

24 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 24

25 3/8 inch Slug Test January Slug Fill 1-30 Slug Fill After 2 day Storage Time= 44 sec Distance= cm Time= 41 sec Distance= cm Time= 140 sec Distance= cm Time= 138 sec Distance= cm 25

26 Any Questions? 26

27 Backup Slide: Storage test retrieval 3/16 27

28 Backup Slide: 3/8 inch Storage Test January 30 Tank Mean: ppm Coils Mean: ppm 28