Thermal Modeling of the CX Satellite

1. Thermal Modeling of the CX Satellite Jacob Boettcher Thermal Team Lead 4/5/02

2. Overview • Brief description of the thermal design process • Discuss the reasons for an orbit revaluation • Describe the procedure used to perform the orbit revaluation • Present the results

3. Thermal Design Philosophy • Thermal Control System had to be entirely passive • Places requirement that the spacecraft absorb and emit the right balance of radiation • Required accurate model of the thermal environment • Must know if the spacecraft can achieve a steady thermal state

4. Thermal Modeling Process • Create 3-D model of the spacecraft for radiation view-factor calculation • SUPVIEW • Determine the Beta Angle • FINDB6 • Calculate Thermal Inputs • ALBTIME2 & ALBEDO • Determine overall radiation model • REFLECT • Input thermal conductances and capacitances into model to get temperature profiles • TAK III

5. Reasons for Orbit Revaluation • CX was designed to operate in a particular orbit • Altitude: 705 km; Local Time: 10am-10pm • Needed to see if other orbits would satisfy: • Power requirements (solar panels) • Science requirements (instruments) • Thermal requirements (radiation budget)

6. Evaluated Orbits • Selected based on the following criteria: • Must be sun-synchronous (constant beta angle) • Science must have pass time between 9am-9pm & 12am-12pm • Altitude must be above 500 km (drag effects) • Power required local time of 10:30am-10:30 pm or earlier • Each ran with hot and cold case values for Solar flux, Earth IR Emission, and Direct Solar Albedo

7. Subsystem Thermal Requirements

8. Results

9. Conclusions • No single orbit satisfied all thermal requirements • Science subsystem only subsystem not to be satisfied by any other orbit • Closer to the original orbit the better • All subsystems, except Science, satisfied with local times between 10am-10pm & 10:30am-10:30pm

10. Questions?