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Ocean Color Experiment Ver. 2 (OCE2) ~ Concept Presentations ~

Ocean Color Experiment Ver. 2 (OCE2) ~ Concept Presentations ~. Thermal Mike Choi April 27, 2011. Thermal Requirements. Power Dissipation. Orbit Parameters. Sun synchronous, near-polar, near-circular orbit Crossing equator at 1100-1300 local time 700 km altitude

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Ocean Color Experiment Ver. 2 (OCE2) ~ Concept Presentations ~

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  1. Ocean Color Experiment Ver. 2 (OCE2) ~ Concept Presentations~ Thermal Mike Choi April 27, 2011

  2. Thermal Requirements

  3. Power Dissipation

  4. Orbit Parameters • Sun synchronous, near-polar, near-circular orbit • Crossing equator at 1100-1300 local time • 700 km altitude • 98.16º inclination

  5. Beta Angle and Eclipse: 1300 Equatorial Crossing

  6. Beta Angle and Eclipse: 1200 Equatorial Crossing

  7. Beta Angle and Eclipse: 1100 Equatorial Crossing

  8. Detector and Pre-Amp Heat Rejection System Aluminum Thermal Box for Silicon PIN (Cold Biased and Actively Controlled by Heaters) Heat Conduction from Detector Enclosures to Aluminum Thermal Box Aluminum Thermal Box for InGaAs PIN (Cold Biased and Actively Controlled by Heaters) Silicon PIN Radiator InGaAs PIN Radiator

  9. Fiber Optics Thermal Control Heaters & Thermostats for Fiber Optics Enclosure Which is Covered with MLI

  10. Operating Mode Heater Circuits with Electronics Heater Controller *Assuming InGaAs not adjacent to each other

  11. Operating Mode Heater Circuits with Mechanical Thermostats

  12. Survival Heaters

  13. Radiator and Heater Power Sizing • Radiators are sized in worst hot operating case • Operating mode heater power is sized in worst cold operating case • GSFC Gold Rules call for a maximum of 70% heater duty cycle for an active heater control thermal design • In sizing heater electrical resistance (R), orbital average heater power shall be no more than 70% of peak heater power (V**2/R) • Valid for both bang-bang and PID controllers

  14. Thermal Model S/C Bus Solar Array Radiators OCE2

  15. Thermal Model 1100 Equatorial Crossing, -17˚ Beta Solar Vector 98.6 Minute Orbit 34.5 Minute Eclipse Spacecraft enlarged to show its orientation

  16. Radiator Size Predictions InGaAs PIN & Preamp Radiator MEB, MCEB & Digitizer Radiator Silicon PIN & Preamp Radiator

  17. Radiator Area

  18. Radiator Area Reduction Option • A radiator with grids is an option for reducing radiator footprint - Flown on Swift BAT Swift BAT Radiator (Grids increased radiator area by 80% but only increased effective radiator area by 30%)

  19. Operating Mode Heater Power

  20. Thermal System Mass Estimate

  21. Conclusions • Radiator area is very large because power dissipation is very high • Pocketed radiator increases effective area but increases mass significantly • Could accommodate silicon PIN and preamp radiator as part of a circular disc radiator

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