Membrane Structures for Communications Satellites

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Membrane Structures for Communications Satellites

• Present recent successes in deployment of polymer
  membrane structure
• Discuss properties that enabled the product
• Optical tailoring of surface
• Process control to reduce thermal shrinkage
• Thermal control issues
• Discuss emerging applications and areas of
  research
• Solar sails
• Optics
• Rf structures

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Hughes HS702 Summary
SRS and HSC Co-developed the Reflector Panels for
the 702.

• SRS Is the Exclusive Provider of Reflector Panels
  for the 702 Program.
• Currently have Orders for Over 11 Satellites.
• Four are on-orbit.
• G11, Anik F, Pas 1R, Thuraya
• Represents 2B in satellite assets being powered
  in Geo currently
• 160 2 meters of film per satellite
• Film is 1 mil material supported by 5 mil edge
  designs.

• Surface Designed for Tuned Optical Properties
• CP1 Panels Are Extremely Flat With Isotropic
  Material Properties
• All Secondary Components Made From SRS CP1
• Aluminum Coated Both Sides

Patented Technology
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General Philosophy of Approach

• Utilize processes which allow film structures to
  be fabricated from materials which can be
  tailored for specific applications
• Allows user to reduce anisotropic properties
• Control properties to some extent
• Vary thickness of material
• Control product from monomer state
• Construct films in a variety of shapes
• Flat
• Parabolic
• Segmented compound curvatures

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Materials Used
Initial Materials Monomers -- 6-FDA 1,3-3APB 4-B
DAF

• SRS Exclusive licensed CP1/2 material from NASA
  LaRC
• UV, e-rad resistant
• Flight qualified at BSS for 15 year GEO life
• For high performance applications consider
  specialty film not manufactured in large
  quantities.

Use the Highest Grade Monomer
Polyamic Acid Prep 6-FDA 4-BDAF (CP1)
Polyamic Acid Prep 6-FDA, 1,3-3APB (CP2)
Viscosity Rise Indicates Quality
Chemical Imidization Procedure (stabilizes
reaction)
Precipitation Procedure (to make solid)
Perform Thermal Analysis to Assure High Quality
Drying the Precipitate (Imide powder)
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Optical Properties (Key)

• Tuned diffusivity based on Flight specifications
• Increased flatness due to the material and
  processes used to product CP1 film
• Isotropic material properties
• Results in evenly distributed solar source on PV
  array

Presented by C. Gelderloos, 28th IEEE PVSC
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Thuraya Launch

• Five Panel Array Deployment

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G11 Deployment at GEO

• First satellite launch and deployment of membrane
  concentrator.

Hughes Award and NASAs Commercial Invention of
the Year
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Membrane Structures Applications and Requirements
5 meter RF antenna
4 meter non-imaging solar collector
flat film mirror
Solar Collector
Membrane Optics
RF Antenna
RMS Wavefront Error
1-5x10-3 meter
lt1x10-3 meter
150x10-9 meter
RMS Slope Error
NA
2x10-3 Radian
1x10-6 Radian
RMS Thickness Variation
10
10
75x10-9 Meter
Conductivity
High
Charging
Charging
Optical Reflecting
NA
High
High
Increasing Difficulty
10
1000
1
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Large Aperture Optics

• Working with AFRL Directed Energy Directorate to
  make an optical imaging membrane.
• Processing and monomer purity are the enablers
  for membrane optics.

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SRS Technologies CP1 Film
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Carbon Nanotubes as Process Modifiers

• Carbon Nanotubes were added to SRS CP1 film to
  alter the material properties of the films.
• Three different mixture ratios were used 0.5,
  2.5, and 5.0.
• CTE decreased as Carbon increased as shown in
  the graph below
• Surface roughness increased with of Carbon.
• Opacity increased with Carbon 0.5 Light
  Grey, 5.0 Black
• There appears to be a slight increase in strength
  with a maximum occurring between 0.5 and 5.0.

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Metallizing Reaction Mechanism

• Desire to go to higher frequency applications
• Polymeric material becomes a player in the
  insertion loss.
• Thermal Control of composite structures are an
  issue.

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Conclusions

• Newly developed polymers and processes are being
  used to enhance the performance of space
  satellites.
• We are active in RD which will reach the
  warfighter.
• The Chasm has been crossed.

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Solar Sails

• x

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Use Government Labs

• Work in large facilities that have
  state-of-the-art equipment

NASA MSFC Dynamics Vacuum Chamber
NASA GRC 2x3 m Off-Axis Concetrator in Tank 6
NASA MSFC Large Mandrel Machining
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Other Projects