FIELDS SPP meeting Thermal MLI requirements

1. FIELDS SPP meetingThermalMLI requirements G.K.Martin 2013-06-26

2. 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

3. 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

4. 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

5. 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)

6. 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

7. APL Estimate for FIELDS blankets

8. 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)

9. 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

10. 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)

11. 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

12. 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