Stratospheric Ozone Stratospheric Ozone ExperimentExperiment

26 May 200526 May 2005

Donald SwartDonald SwartChristopher BarberChristopher Barber

Michael O’LearyMichael O’LearyGregg RidlonGregg Ridlon

Robert ScheffersteinRobert Schefferstein

GoalsGoals

Measure UVB and UVC attenuation Measure UVB and UVC attenuation through the stratospherethrough the stratosphere

Approximate the thickness of the Approximate the thickness of the ozone using attenuation dataozone using attenuation data

““Map” the ozone layerMap” the ozone layer Measure pressure as a function of Measure pressure as a function of

altitudealtitude

Overview of ResultsOverview of Results

UV Data: UncollectedUV Data: Uncollected

Cause: Programming ErrorCause: Programming Error

Pressure Data: Collected successfullyPressure Data: Collected successfully

UV DataUV Data

Circuit retested on the ground Circuit retested on the ground successfullysuccessfully

Programming error caused our UV Programming error caused our UV readout to come from an incorrect readout to come from an incorrect ADC pin.ADC pin.

Four ADC pins, only three were used Four ADC pins, only three were used (ch 0,1,3), and our data was (ch 0,1,3), and our data was recorded from channel 2, which had recorded from channel 2, which had no signal being fed into itno signal being fed into it

Pressure DataPressure Data

Pressure measurements were very Pressure measurements were very successful in showing the variation of successful in showing the variation of pressure as a function altitude.pressure as a function altitude.

After correcting the zero offset for our After correcting the zero offset for our circuitry our pressure graph looks circuitry our pressure graph looks accurate, within 17 HPa of the known accurate, within 17 HPa of the known ground pressure at launch.ground pressure at launch.

Taking this error into account the lowest Taking this error into account the lowest pressure sustained by our payloads was pressure sustained by our payloads was 93.66 HPa ± 17 HPa.93.66 HPa ± 17 HPa.

Pressure UsesPressure Uses

Adding temperature data to our Adding temperature data to our pressure data (thanks go to LA Tech) pressure data (thanks go to LA Tech) we were able to calculate several we were able to calculate several other pieces of data:other pieces of data:• Air densityAir density• Drag ForcesDrag Forces• Potential TorquePotential Torque

Velocity data was inferred from Velocity data was inferred from altitude and time stamp data.altitude and time stamp data.

Pressure and Altitude vs. TimePressure and Altitude vs. Time

0

20000

40000

60000

80000

100000

120000

12:46:00 13:14:48 13:43:36 14:12:24 14:41:12 15:10:00 15:38:48 16:07:36

Time (HH:MM:SS)

Pre

ssu

re (

Pa)

Alt

itu

de

(ft)

Pa

Altitude (ft)

Velocity and Density vs TimeVelocity and Density vs Time

-60

-50

-40

-30

-20

-10

0

10

12:46:00 13:14:48 13:43:36 14:12:24 14:41:12 15:10:00 15:38:48 16:07:36

Time

Vel

oci

ty (

m/s

) D

ensi

ty (

kg/m

^3)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

Velocity

Mass Denisty

Velocity and Altitude vs. TimeVelocity and Altitude vs. Time

Velocity and Altitude Vs Time

0

20000

40000

60000

80000

100000

120000

12:4

9:30

12:5

6:38

13:0

3:46

13:1

0:54

13:1

8:02

13:2

5:10

13:3

2:18

13:3

9:26

13:4

6:34

13:5

3:42

14:0

0:50

14:0

7:58

14:1

5:06

14:2

2:14

14:2

9:22

14:3

6:30

14:4

3:39

14:5

0:47

14:5

7:55

15:0

5:03

15:1

2:11

15:1

9:19

15:2

6:27

15:3

3:35

15:4

0:44

15:4

7:52

15:5

5:00

16:0

2:08

16:0

9:16

16:1

6:24

16:2

3:32

Time

Alt

. (ft

)

-60

-50

-40

-30

-20

-10

0

10

Altitude (ft)

Velocity

AnalysisAnalysis

Sharp Change in Velocity at UT 15:34Sharp Change in Velocity at UT 15:34• Probable time of SU payload lossProbable time of SU payload loss• Highest “jerk”Highest “jerk”• Greatest potential torque (assuming payloads Greatest potential torque (assuming payloads

weren’t falling “ducks in a row”)weren’t falling “ducks in a row”) Time and altitude correspond to the Time and altitude correspond to the

location of the tropopause; lowest location of the tropopause; lowest temperatures and most brittle state for temperatures and most brittle state for most plasticsmost plastics

Analysis cont.Analysis cont.

Early speculations stated payload Early speculations stated payload possibly lost at tropopause; collected possibly lost at tropopause; collected data reinforces original theories.data reinforces original theories.

Velocity Data too inaccurate to Velocity Data too inaccurate to reliably calculate dragreliably calculate drag• Parachute behavior also unknown, only Parachute behavior also unknown, only

speculatedspeculated

ImproveImprove

• Earlier testing techniquesEarlier testing techniques• Labeling Programs with proper version Labeling Programs with proper version

numbersnumbers• Organized checklist of final assembly Organized checklist of final assembly

stepssteps• Periodic review/revising of checklistsPeriodic review/revising of checklists• Debug ProcessesDebug Processes• TeamworkTeamwork• Time ManagementTime Management

SustainSustain

Circuit DesignCircuit Design Thermal DesignThermal Design Finishing the payload despite Finishing the payload despite

setbackssetbacks Background ResearchBackground Research

AcknowlegmentsAcknowlegments

Lawrence BlanchardLawrence Blanchard Dr. Kevin StokesDr. Kevin Stokes Lester Langford and Stennis Space Lester Langford and Stennis Space

CenterCenter NSBF and NASANSBF and NASA LA TechLA Tech LA ACES PanelLA ACES Panel