1 Thermal Investigation for Accurate Temperature Measurement Team TCTJ Truc Le Cedric Toguem Jonathan Newman

2 Overview Mission Goal Objectives Science Background Tests Overall Design Payload Design Electrical Software Mechanical Payload Development Projected Budget Schedule and Status

3 Mission Goal The goal is to determine why previous LaACES payloads temperature measurements are different in comparison to NOAA temperature measurement.

4 Objectives Determine the effect of the thermal boundary layer on temperature measurements Determine the effects of material and coating of temperature sensors on temperature measurement Have the measurements of the control temperature sensor be similar to NOAA measurements

5 Science Background Troposphere (0 to 12km) : lowermost atmosphere where temperature decreases from 30 to -80 °C Stratosphere (12 to 48km): second lowermost part of the atmosphere where temperature increases from -80 to 0 °C

6 Science : Boundary Layer Thin layer of fluid in contact with a solid body that flows more slowly than the rest of the fluid As the payload gains altitude in fluid air, the boundary layer around it will be affected by heat transfer processes

7 Science: Radiation Electromagnetic radiation emitted from the surface of an object in the form of heat due to the objects temperature If an object is warmer than its surrounding environment, it will emit more radiation in the form of heat into the surrounding environment than it will absorb in order to attain thermal equilibrium

Science: Previous Data

9 Test 1: Radiation Test 1 Radiation test: Sun → Electromagnetic radiation → Space → Sensors The test will consist of different color shielding to reflect the electromagnetic radiation from the sun

10 Test 2: Radiation Test 2 Radiation Test: The payload circuitry will emit radiation to the sensor. Distance from the radiation source will determine the amount of heat dissipated

11 Test 3: Boundary Layer Test Sensors are placed at different distance from the exterior surface of the payload Determine how much effect the boundary layer has on the measured temperature

Overall Design

13 Electrical: Sensors 1µA constant current from LM134 Output voltage will then vary from 1mV to 190.8mV (Value based on device’s datasheet – Resistance V. Temperature Table)

14 Electrical: Sensors 7 temperature sensors Model: 44003RC Precision Epoxy NTC Thermistor -80 °C to 50 ° C 1kΩat 25 ° C

15 Sensor Interfacing Sensors’ output voltage will vary from 1mV to mV Payload ADC, from 0 to 3V Will use AD820 op-amp to amplify each sensors’ output

16 Sensor Interface

17 Sensor Interface Vref = 1.5V, R6 = 1kΩ R4 = 0.94MΩ R5 = kΩ

18 Power Supply 6 x 1.5V Energizer L92 Ultimate Lithium (AAA) 9V to BalloonSat 9V to Op-Amps 9V Current sources positive voltage terminal 1.5V Battery to Op-Amps Vref

Supplemental ADC Chip Team will use 7 sensors 4 Channel on BallonSat ADC Team will add another ADC0834 chip New chips’ pin connection will follow the original’s. Ohmmeter will test pin connections

Supplemental ADC Chip (cont.) ADC pinConnection 2P0 3CH4 4CH5 5CH6 6CH7 7GND 8 10&13P13 12P14 14Vcc Added ADC Pin Connection

21 Power budget ComponentCurrent (mA)DurationCapacity BalloonSat51 (measured)4204mA-h Thermistors (x7)≤ 0.7 (desired)42.8mA-h AD820 op-amp (x7)≤ 25 E mA-h LM134≤0.7 (desired)42.8mA-h Max Total mA-h

22 Software: Data Format Table DescriptionByte Extra variables2 Time-Hour1 Time-Minute1 Time-Seconds1 Sensor-Inside wall1 Sensor-Outside wall1 Sensor-Control sensor1 Sensor-Inside B.L.1 Sensor-Outside B.L.1 Sensor-Black coating1 Sensor-White coating1 Total per Loop12 Total Estimated Bytes2880 bytes

23 Software: Flowchart

24 Software: Flight Flowchart

Software: Ground System

26 Exterior Mechanical Design

27 Interior Mechanical Design

Mechanical/electronics interface

29 Weight Budget ComponentWeight (g) Batteries~91 BalloonSat60.4 Op amp Board~30.2 Foamular structure64.1 BalloonSat/Op-amp board attachments ~9 Wiring~10 Booms (Plexiglas Straws)~20 Boom attachments~25 Sensors~1.5 Total~311.2

Thermal Test ActivityTime (min) 1. Acquire dry ice and place it in a cooler2 2. Initialize software1 3. Place payload in refrigerator5 4. Place payload in freezer15 5. Place payload in dry ice cooler30 6. Place payload in freezer60 7. Place payload in dry ice cooler15 8. Return payload to room temperature.5 9. Run program to ensure payload worked5

Vacuum Test ActivityTime (min) 1. Initialize software2 2. Place payload in vacuum chamber Begin evacuating chamber (10 mb/min)1 4. Allow chamber to reach 5mb~ Begin re-pressurizing chamber (35mb/min)~30 6. Run program to ensure payload worked5

Impact Test ActivityTime (min) 1. Initialize software2 2. Go outside with a tape measure and the payload2 3. Put payload at a height of 3 meters and drop.5 4. Analyze damage to determine if current structure is sufficient20

Budget ItemPartRetailerQty.Unit Price Total Price Sensors x744003RC Precision Epoxy NTC Thermistor ment-specialties 10$15.17$ BatteriesEnergizer L92 Ultimate Lithium (4 pack) or local Wal- Mart or Radio Shack $40.00 Constant Current x7 LM234In house ADCADC0834In house Op-ampAD820In house ResistorsVarying valuesIn house???? BoomsPlexiglas strawshttp:// pack $20.00 Op-amp BoardStripboardhttp:// ards.shtml 1$2.00 Payload Structure FoamularIn House Total$214.00

34 Reference 1. Clavius: Environment - heat transfer. November 24, Anne E. Egger "Earth's Atmosphere: Composition and Structure," Visionlearning Vol. EAS Sad Dr Rodrigue – Introduction to physical Geaography. re.html re.html 4. BASIC Stamp 2p 24-Pin Module. dules/tabid/134/ProductID/7/List/1/Default.aspx?SortField=UnitC ost,ProductName. November 25, dules/tabid/134/ProductID/7/List/1/Default.aspx?SortField=UnitC ost,ProductName

35 Questions?