Mozella Bell, Herman Neal, Matthew Ware PACER at Grambling State University Grambling Atmospheric Profile (GAP) Mozella Bell, Herman Neal, Matthew Ware

Science Background The payload will ascend through the troposphere, the tropopause, and into the stratosphere to the upper boundary of the ozone maximum. This figure represents a typical temperature profile of the layers of the atmosphere. However, the specific profile depends on location, particularly the latitude. There is also a seasonal variation with the tropopause at higher altitudes in summer at latitudes smaller than 60°. The GAP experiment will measure the profile over East Central Texas (35° latitude) in May.

Science Background (continued) The tropopause is characterized by a region several kilometers thick where the temperature is relatively constant. High altitude sounding measurements indicates that temperature over 2 km altitude range varies 3 °C or less. This figure shows the pressure and density profiles as determined by the NRLMSISE Standard Atmosphere Model. The atmosphere may be considered as an ideal gas. The ideal gas law may be used to calculate the density from measurements of pressure and temperature: r = MP/RT.

Science Objectives 1. Identify the zones of the Earth’s lower atmosphere. 2. Determine the altitude of the tropopause. 3. Develop a temperature profile of the atmosphere. 4. Develop a pressure profile of the atmosphere. 5. Develop a density profile of the atmosphere. 6. Compare accepted models of the atmosphere to measurements. 7. Present findings

Science Requirements Make measurements every 15 seconds. Calculate density within 5% uncertainty which includes: Measure temperature to within 1 °C (0.5% at the tropopause). Measure pressure to which 1 mbar (5% at the tropopause). Determine the altitude to within 100 meters.

Technical Objectives 1. Build and fly a payload and retrieve the data. 2. Measure temperature over the range -80 ˚C ≤ T ≤ 40 ˚C. 3. Measure pressure over the range 5 mbar ≤ P ≤ 1000 mbar. 4. Calculate the atmospheric density using the ideal gas law. 5. Store thermodynamic data in memory contained within the payload control computer. 6. Correlate payload data with mission telemetry data to determine the altitude of each measurement.

Technical Requirements Payload must remain intact from launch to recovery. Power system must operate over the temperature range -80 °C ≤ T ≤ 40 °C with the capacity to power the BalloonSat, sensors, and data archive for the duration of the flight. Temperature sensor able to measure over the range -80 °C ≤ T ≤ 40 °C. Pressure sensor able to measure over the range 5 mbar ≤ P ≤ 1000 mbar. Record time to 15 second accuracy. Data archive system with the capacity to store measurements by the sensors and real time clock for the duration of the flight (approximately 750 data records) Ground system which can download, analyze, and graphically display payload measurements.

Sensor Subsystem Schematic

Power Subsystem Schematic

Data Storage Format Name Bytes Sequence No. 2 Hour 1 Minute Seconds Temperature Outside1 Temperature Outside2 Temperature Inside Pressure

Payload Construction The GAP payload is constructed using a material called Styrofoam. This type of material can withstand extreme temperatures, pressure and shock from the landing of the payload. The material that will reinforce the payload is silver mylar which can withstand cold temperatures and also work as a good insulator.

Mechanical Design Closed Capsule (Two-Side View) Closed Capsule (Three-Side View)

Mechanical Design (continued) Lid (Top View) Lid (Side View)

Mechanical Design (continued) Capsule Interior w/o BalloonSat Capsule Interior w/BalloonSat

Thermal Test

Power Budget Component Voltage (V) Current (mA) Power (mW) Duty Cycle (%) BalloonSat Subsystem 8–12 60 720 100 Data Archive On BalloonSat Temperature Sensors 8 96 Pressure Sensor 5

Weight Budget Components Weight (grams) Case 122 Two Exterior Temperature Sensors 11 Pressure Sensor Included on Daughtercard Batteries for BalloonSat 108 Power Connectors 8 BalloonSat and Daughtercard 149 Total 397

PACER GAP Flight Badge The valley is a GAP in the mountains The tiger is leaping the GAP while being lifted by the balloon. The balloon escapes the boundaries of the patch just as we had to think outside of the box in order to finish the project

Acknowledgements PACER LaSPACE, the Louisiana Space Grant Consortium National Science Foundation NASA Columbia Scientific Balloon Facility Louisiana State University-Baton Rouge