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AATSR Function & Performance

AATSR Function & Performance. Thermal Cooler Performance Scan mirror performance. In-Orbit Temperatures Vs. Flight Predictions. Thermal Stability. Blackbodies Orbital variation ~ ± 0.1 °C Rate of change <0.015 °C per two minutes (reqt. <0.02°C) Fore-Optics Orbital variation ~ ± 0.5 °C

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AATSR Function & Performance

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  1. AATSR Function & Performance • Thermal • Cooler Performance • Scan mirror performance

  2. In-Orbit Temperatures Vs. Flight Predictions

  3. Thermal Stability • Blackbodies • Orbital variation ~ ±0.1°C • Rate of change <0.015°C per two minutes (reqt. <0.02°C) • Fore-Optics • Orbital variation ~ ±0.5°C • Rate of change <0.04°C per two minutes (reqt. <0. 2°C) • FPA Baffle Tube • Orbital variation ~ ±0.5°C • Rate of change <0.04°C per two minutes (reqt. <0. 2°C)

  4. Temperature Trends

  5. Thermal - Summary • In-orbit temperatures for all units show positive margins compared to the EOL predictions • Fore-optics temperatures meet and exceed requirements for actual temperature and orbital stability

  6. Cooler Performance - Cooldown

  7. Cooler Performance – Trends Max commanded compressor A amplitude = 2.679 Software increases amplitude to maintain a commanded FPA baseplate temperature Thermal load increasing with time as water condenses, with the rate of condensation slowly reducing as the mission progresses and ENVISAT-1 loses its atmosphere.

  8. Cooler Performance - Summary • Cooldown to 80K achieved in ~5 hours • Cooler software is controlling the compressor amplitude to maintain the FPA temperature at 80K as required • Thermal load on the FPA increases with time as water condenses on surfaces • Recovers to nominal conditions after outgassing • Rate of condensation slowly reduces as the mission progresses and ENVISAT loses its atmosphere.

  9. Scan mirror performance • Average rotation rate = 150.0032ms 0.42ms • Determined from average time difference between source packets (OBT resolution 4ms) • Current when running ~ 0.35A and is stable • Scan mechanism running in as expected, jitter levels have become almost negligible (Some scan mirror jitter can be expected during early stages of mission while the lead-bronze lubricant tracks are being established which will improve with time)

  10. Scan Mirror Stability

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