Section 7 Part 3 Thermal Accommodation

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Section 7 - Part 3Thermal Accommodation

• . . . Nick TetiEO-1 Lead Thermal EngineerSwales
  Aerospace

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Agenda

• Thermal Requirements
• Design Philosophy and Accommodation
• Thermal Analysis
• Louver Layout
• Actions / Concerns

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Thermal Requirements

• Accommodate Hyperion without adding additional
  heater power and still maintain temperature range
  of 0 - 40C for the spacecraft, with a 10C
  margin (Note Worst Case Predictions are 10 -
  30C for Nadir Deck)
• TRW provides geometric math model in TRASYS,
  SSPTA or TSS format and thermal math model in
  SINDA format
• Hyperion environmental testing includes thermal
  balance thermal vacuum before delivery to
  spacecraft
• Thermal Interfaces
• Temperature control at the Nadir Deck interface
  is maintained by thermostatically controlled
  heaters and MLI blankets. The Nadir Deck is
  maintained between 0C and 30C during all
  mission phases.
• The HSA mounting interface is thermally isolated
  from the nadir deck
• The HEA CEA are thermally coupled to the nadir
  deck, however, they will utilize individual
  radiators on the boxes to radiate the majority of
  excess heat to space. The radiators will be sized
  so that NO heater power is needed to maintain the
  lower temperature limits.

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Design Philosophy and Accommodation

• EO-1 spacecraft is a cold-bias design
• Passive Radiators
• Redundant survival heaters
• Designed to minimize make-up heater power
• Baseline estimates are 0 Watt for nominal orbit
  and 12 - 15W for battery panel during standby
  (not safemode)
• Louver to be added to reduce battery heater power
• Switch MLI blankets from black Kapton to
  aluminized Kapton on Nadir deck, except for areas
  identified by MIT/LL (e.g., nadirdeck surface in
  front of FPA radiator)
• Four available inputs for temperature sensors

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Thermal Analysis

• Update ALI thermal model w/ALICE box mounted to
  Pallet and Radiator removed
• Parallel design and analysis effort with MIT/LL
• ALI and ALICE geometric model changes made by
  Swales
• SINDA thermal model changes based on inputs from
  MIT/LL
• Geometric Model update from MIT/LL not received
  as of 9/16
• Assess impact of removing ALICE Radiator to
  accommodate Hyperion
• Maintain temperature requirements?
• Additional heater power?
• Add geometric representation of HSA, HEA and CEA
  to spacecraft model and additional nodes to SINDA
  thermal model
• Trade study to determine impact of HEA and CEA to
  current thermal design
• Verify that nadir deck stays within temperature
  limits and that no heater power is required
  during standby orbits
• HSA external radiation model only (radiation
  blocker)

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Scheduled Thermal Analysis

• TRW Thermal Model Status
• TRWs SINDA/G model obtained at Hyperion CDR
  converted to SINDA/FLUINT (non-standard data file
  did not convert easily)
• TRASYS model received at Hyperion CDR did not
  include radiators on HEA and CEA
• Analysis pending delivery of Updated TRW thermal
  models
• Integrate TRW HSA, HEA, CEA thermal models with
  EO-1 ALI thermal models
• Higher fidelity CEA and HEA box design
• Modify nadir deck MLI properties
• HSA internal radiation model
• Updated heater control logic
• Re-size spacecraft radiators based on new
  satellite configuration
• Since power is critical, need maximum-fidelity
  and precision in analysis

The Following Charts Are Based On Swales Thermal
Models of Hyperion
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Solar Absorptivity of Thermal Model
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Hot Bias Temperature Predictions
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Hot Bias Temperature Predictions
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Louver Mechanical Layout
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Thermal Actions / Concerns

• Addition of Hyperion Instrument will require
• Modifications to spacecraft thermal model
• Thermal models needed for Hyperion Sensor and
  Electronics
• Additional conductive path through HEA and CEA
  Mounting Plate
• Assessment of Battery Thermal Control (additional
  heat transfer path)
• Updating Survival Heater Power (Stand-by and
  Safe-mode)
• Assessing influence of additional heat into nadir
  deck from HEA and CEA
• Summary of Thermal Action Items Imposed at
  Hyperion CDR
• Delta Thermal CDR for TRW suggested
• Add internal radiation model for HSA to thermal
  model
• Provide power profiles for HSA, HEA and CEA
  (science, standby safemode)
• Provide operational, survival and qualification
  temperature requirements
• Provide details for thermal testing (Thermal Vac
  and Thermal Balance)
• Describe heater layout, design and duty cycle
  (50 _at_ 28v)