1. High Performance MLI for Cryogenic Hardware
Leslie Buchanan
Steve Buerger
March 13, 2003

2. Today’s Talk The nature of MLI - theory vs practice Basic principles
High performance MLI
Results
Conclusions
2/5/2019

3. Theory vs Practice Simple, versatile technology.
Radiation shields to minimize heat transfer
Customized for wide range of applications.
Implementation degrades performance.
Seams to facilitate installation and access
Penetrations to accommodate supports, plumbing, cabling, and venting
Fastening devices to attach blanket to hardware
Real estate limitations cause tight clearance
IRAS
SBIRS HEO TCS
PRSA
2/5/2019

4. MLI (Multi-Layer Insulation) - A Versatile, Effective Technology
Purpose - Create Adiabatic Surface
Cryogenics-Insulate cold surface from warm electronics
S/C-Insulate warm electronics from space
Construction
Inner Layers
10 min to 50 max
Double Aluminized Mylar, .25 mil thick
Dacron Net Spacers
Outer Layers
Space Exposure
Maintain Temperature
Provide ESD prevention
Provide atomic oxygen and micrometeoroid protection
Protect inner layers during installation and handling
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5. Minimize Heat Leak Through MLI
MLI - Basic Principles
Minimize Heat Leak Through MLI
radiation shield theory
through thickness
lateral
2/5/2019

6. MLI - Basic Principles Radiation Shield Theory
Parallel planes, no shield
Multiple Shields 1 2 1 2 N
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7. MLI Best Practices Wherever Possible
High Performance MLI
Low emissivity surfaces on layers
Optimize number of layers
Maximize loft
adequate clearance
CTE considerations
Minimize effect of seams, gaps, and penetrations
Provide vent paths
Minimize temperature mismatches
2/5/2019

8. Application – Test Unit for Cryogenic Cooling System
Requirements
Design high performance MLI
Critical to mission success
Requirement:
Goal:
Provide ease of disassembly
Facilitate post MLI installation hardware changes
Meet tight schedule
Design and produce MLI in parallel with hardware
4 months start to finish
2/5/2019

9. Number of Layers Optimized for Available Clearance and Ease of Installation
Design Goal
Reference - C.W. Keller, Thermal Performance of Multilayer Insulation, Final Report, prepared for NASA Lewis Research Center Contract NAS , Lockheed Missiles and Space Company, Sunnyvale, CA, 1971, NASA CR
2/5/2019

10. Number of Layers Optimized for Available Clearance and Ease of Installation
Design Goal
SBIRS GEO Test Data
Reference - C.W. Keller, Thermal Performance of Multilayer Insulation, Final Report, prepared for NASA Lewis Research Center Contract NAS , Lockheed Missiles and Space Company, Sunnyvale, CA, 1971, NASA CR
2/5/2019

11. Seam Selection Criteria
Thermal Performance
Minimize radiation line-of-sight
Match temperature profiles of adjacent edges
Minimize compression of shields in joint formation
Allow gas venting
Producibility
Edges easily fabricated
Facilitate fastening techniques
Ease of assembly/disassembly on hardware
2/5/2019

12. Sub-Blanket Fastening Device Selection Criteria
Thermal Performance
Minimize conduction through fasteners
Minimize radiation through fastener penetrations
Allow interstitial gas venting
Structural Integrity
Resistance to tensile loading
Resistance to shear loading
Allow clearance for loft
Control ballooning
Producibility
Ease of assembly/disassembly
2/5/2019

13. Blanket-to-Hardware Attachment Selection Criteria
Thermal Performance
Minimize conduction through fasteners
Minimize radiation through fastener penetrations
Allow interstitial gas venting
Structural Integrity
Resistance to tensile loading
Resistance to shear loading
Allow clearance for loft
Control ballooning
Producibility
Ease of assembly/disassembly
2/5/2019

14. Penetration Selection Criteria
Thermal Performance
Minimize radiation line-of-sight
Minimize radiation from penetration into layers
Minimize conduction from MLI to penetration
Allow gas venting
Producibility
Ease of installation on hardware
2/5/2019

15. Ball MLI Center Charter – Develop and Communicate MLI Technology
We design, fabricate, and install MLI blankets
Standard performance MLI, s/c
High performance MLI, cryogenics
Standard processes company wide
Documented in Quality Business System
MLI team
Thermal Engineer
MLI Designer/Production Engineer
MLI technicians
00-114d
2/5/2019

16. Full-up MLI Fabrication Capability
Controlled facilities, clean rooms
Capacity: 80 feet of lay-up tables, 2 sewing stations, 12 cutting stations
CAD templates
Cutting techniques
Hot knife
Laser cutter (high quantity jobs)
Capable of processing all insulation materials including Mylar, Kapton, Teflon, beta-cloth, net/mesh films with all metallized finishes such as aluminum, gold, silver, and inconel
Processes used include stitching, venting, attachment (snaps, grommet, Velcro, bonding), and ground strap installation
2/5/2019

17. MLI Best Practices Applied on Test Unit
Component
MLI Design Performance
Minimize Radiation Lines-of-Sight through MLI
Minimize Conductive Paths through MLI
Minimize Lateral Conduction along MLI Layers
Minimize radiation from penetration into MLI
Maximize Loft
Allow Gas Venting
Maximize Ease of Assembly and Disassembly
Maximize Ease of Fabrication
Blanket-to-Hardware Attachment Method
High
Moderate
N/a
Sub-blanket Attachment Method
Seams
Clearance
Blanket Pattern Contouring
Material Shrinkage at Cryogenic Temps
Penetrations
(Support Struts, Cold Rods, Windows)
Low
(GSE Cooling Lines, Cables)
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18. Tips and Tricks Number of layers optimized using Lockheed correlations
Developed seam and penetration treatments to minimize performance degradation
Optimized seam locations
Facilitate ease of installation and disassembly
As few as possible
Layer temperature profiles matched at interfaces
Used streamlined design and production processes
company standard
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19. MLI Performance Exceeded Design Goals
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20. Conclusions Best MLI practices wherever possible
Work concurrently with mechanical to develop “MLI friendly” configuration
Compromises made to simplify implementation, facilitate disassembly, and where high performance unnecessary
Test unit excellent opportunity to verify concepts
2/5/2019