FIELDS SPP meeting Thermal MLI requirements

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FIELDS SPP meeting Thermal MLI requirements. G.K.Martin 2013-06-26. SPP Observatory Thermal Overview. Thermal Protection System (TPS) Shields the S/C from the sun during closest approach Transition Structure Assembly (TSA) Conductively isolates the S/C from the TPS Solar arrays
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FIELDS SPP meetingThermalMLI requirements G.K.Martin 2013-06-26 SPP Observatory Thermal Overview Thermal Protection System (TPS)
  • Shields the S/C from the sun during closest approach Transition Structure Assembly (TSA)
  • Conductively isolates the S/C from the TPS Solar arrays
  • Two DOF to track the sun (PPT) and move through the umbra & penumbra for optimum solar load CSPR panels
  • Dissipates heat via a water cooled pump system to maintain thermal heatload on solar arrays Barrier blanket
  • Thermal blanket suspended above the top of the S/C that radiatively decouples the backside of the TPS from S/C components Spacecraft
  • Internal heat sharing within S/C design
  • MLI is stood off 2”
  • Aluminum facesheets
  • Louvers on S/C body
  • Conductively isolated to instruments via bracket
  • Radiatively view to instruments is TBR on individual basis (currently radiatively isolated)
  • Unless otherwise noted, the components described have a negligible radiative (no conductive) coupling between TPS & S/C mounted instruments MLI Requirements
  • ICD
  • TheInstrument to observatory MLI blanket interface is the joint responsibility of the Instrument IDT and JHU/APL. Design details will be developed cooperatively.
  • Blanket interfaces shall be captured in the mechanical drawing, with adequate closeout to the spacecraft blankets, and include mechanical tie downs and/or closeout locations [INST_067].
  • The Instrument IDT is responsible for MLI fabrication and installation, unless other arrangements have been made with the spacecraft thermal engineer.
  • The Instrument surfaces with blankets shall have a minimum clearance of 0.635 centimeters from all other surfaces [INST_068].
  • Blanket venting requirements are TBD.
  • External blanket surface electrical resistivity is required to meet the requirements established in the EMECP. The size of all non-conductive areas shall be reported to the JHU/APL system engineer [INST_069]. Approval of non-conductive areas requires approval of JHU/APL in view of electrostatic requirements. At least two (unless otherwise agreed) grounding straps shall be provided for each thermal blanket to meet observatory-level electrostatic requirements installed by the Instrument team [INST_070]. The spacecraft thermal team shall provide ground straps for the Instrument. Ground strap details will be included on the instrument specific ICD.
  • Instrumentsinternal to the spacecraft bus shall not be blanketed [INST_071].
  • Other
  • Components exposed to temperatures > 150°C requires high temperature MLI (S/C mounted instruments do not fall under this category)
  • Instrument shall have an MLI attachment location for S/C blanket close-outs (mechanical requirement)
  • Labor costs for APL built blankets is the instrument responsibility
  • MLI Clearance Requirements 0.25” INSTRUMENT INSTRUMENT Close-out for S/C blanket Clearance required from instrument surface with MLI to any adjoining surface is 0.25” Instrument shall design a mechanical close-out for the S/C blanket interface FIELDS MLI LocationAntenna Preamps and Hinges Antenna preamps MLI (high temperature) on box only, 5 of 6 sides Quantity: 4 (each test & flight) Antenna hinges MLI (high temperature) Quantity: 4 (each test & flight) FIELDS MLI LocationFGMs, SCM MLI on all 3 sensors
  • Lay-up = mylar-dacron (15 to 17 layers)
  • (MAYBE high temperature layup, TBD)
  • GSFC will provide FGM blankets
  • APL is responsible for any boom blankets
  • APL Estimate for FIELDS blankets APL MLI Building Process
  • For teams that APL is building blankets
  • Sent quotes to PM
  • Verify delivery dates
  • Will meet requirements/work together
  • APL blanketing process
  • Build rapid prototype (in quote)
  • Build MLI template
  • MLI drawings (lay-ups)
  • Build test blankets
  • Modify test blanket template for flight blankets
  • Information required from each team
  • Need drawings/design
  • Wiring locations
  • Purge lines
  • Close outs (specifically for odd locations (i.e. near apertures)
  • MLI Lay-ups
  • High temperature MLI lay-up
  • Embossed aluminized Kapton (10 layers)
  • Outer layer of StaMet on Black Kapton
  • Standard MLI lay-up
  • Mylar-dacron alternating layers (17 layers)
  • Outer layer of StaMet on Black Kapton
  • Thermal RequirementsInternal boxes and Contamination
  • Internal boxes (SWEM)
  • Surface finish shall have an IR emittance >0.85
  • Flatness requirement of 0.025 cm
  • Boxes will have thermally conductive mounting interface (CV-2946, TBR)
  • Internal boxes shall NOT have MLI
  • Contamination
  • Bakeouts will be performed of subsystems and components in order to ensure low spacecraft outgassing.  Bakeout candidates among others would include among; solar arrays, flight harness, MLI, boxes. (Bake-out requirements for high temperature components are TBD)
  • Thermal Resources
  • Mass
  • All thermal mass associated with the instruments is carried in the instrument MEL, including S/C controlled thermal hardware such as survival heaters
  • Instrument MELs should include brackets, MLI, heaters, harness, temperature sensors, etc.
  • S/C carries the mass up to interface for heaters & sensors
  • Temperature sensors
  • Each S/C mounted instrument will be allocated survival S/C controlled survival temperature sensors
  • Additional sensors required by the instrument are instrument responsibility
  • Heater power
  • Operational heater power is the responsibility of the instrument & maintained in the instrument power budget
  • Survival heater power (table) is maintained in the S/C power budget
  • FIELDS allocation for survival heater power is 5.0 W
  • Thermal Hardware
  • Procurement
  • Thermal hardware procurement is the responsibility of each instrument provider unless otherwise agreed upon
  • Heaters
  • Heater procurement by S/C can be arranged assuming schematic & funds are provided
  • Temperature sensors (thermistors)
  • Temperature sensors in S/C allocation will be provided by APL
  • MLI
  • APL will provide blanket material to all instrument teams
  • Ground straps
  • APL will provide ground straps for instruments & blankets
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