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

2 Overview Mission Goal Objectives Science Background Technical Background Payload Design Electrical Software Mechanical Payload Development

3 Mission Goal The goal is to determine why previous LaACES payloads failed to correctly measure temperature in comparison to NOAA.

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 Temperature change in the Atmosphere 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 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 Heat Transfer Modes Heat can be transferred in three different ways: - Conduction - Convection - Radiation

8 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

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

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

13 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 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

15 Sensor Interface

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

17 Control Electronics

18 Power Supply 6 x 1.5V Energizer L92 Ultimate Lithium (AAA) 9V to BalloonSat 9V to Op-Amps pin 7 1V from BalloonSat’s Voltage regulator to Op-Amp Vref 9V Current sources positive voltage terminal

19 Power Supply

20 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

21 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

22 Flight and Post-Flight Software

23 Programming Flow Chart

24 Flow Chart During Flight

25 Exterior Mechanical Design

26 Interior Mechanical Design

27 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

28 Payload Development Plan Mechanical ◦ Thermal Testing ◦ Boom Testing ◦ Attachment prototyping ◦ Impact test to find best design to store components ◦ Maintain payload within regulation

29 Payload Development Plan Electrical ◦ Design the circuitry of the system ◦ Determine how well the components will function in flight climate ◦ Determine methods of calibration of the sensors

30 Payload Development Plan Software ◦ Determine if extra memory will be needed and how to access it ◦ Determine how to access ADC ◦ Determine methods of calibration

31 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

32 Questions?