CubeSat Design for Solar Sail Testing Applications

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CubeSat Design for Solar Sail Testing Applications

• Phillip Hempel Paul Mears
• Daniel Parcher Taffy Tingley

October 11, 2001
The University of Texas at Austin
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Presentation Outline
Project Goal
Management Structure
Satellite Systems
Budget
Future Work
Conclusion
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Project Goal

• Design a Test Platform for Solar Sail Propulsion
  Technology
• Measure Thrust
• Measure Solar Sail Efficiency

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Management Structure

• Daniel Parcher
• Project Manager
• Tracking Systems Department Head
• Electronics Department Head
• Phillip Hempel
• Mechanical Systems Department Head
• Taffy Tingley
• Propulsion Systems Department Head
• Paul Mears
• Orbital Trajectory Department Head

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CubeSat Project Background

• Sponsored by Stanford University
• Utilizes picosatellite satellite Designs that
  perform some scientific task
• Different CubeSat launches provide different
  initial conditions

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Constraints

• CubeSat Prescribed Constraints
• 10cm Sided Cube
• 1 Kg Weight
• Timing System to Delay Power-On
• Space-Flown Materials
• Adopted Constraints (for Simplicity and
  Reliability)
• No Attitude Control
• No Powered Systems (except required Timer)
• No Communications Systems

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Presentation Outline
Project Overview
Management Structure
Satellite Systems
Budget
Future Work
Conclusion
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CubeSat Required Systems

• Timer
• RDAS accelerometer/timer
• Voltage outputs to trigger system
  events
• Casing
• Aluminum
• Kill Switch
• Attached CC reflectors

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Tracking / Communcations

• No Satellite Communication
• Tracking performed with corner cube reflectors
• determine position, rotation, acceleration
• Corner cube reflectors to be supplied by Banner
  Engineering Corp.

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(No Transcript)
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Mechanical Systems

• Phillip Hempel

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Satellite Components

• Frame/ Corner Cube Reflectors
• Kill Switch/ Timer
• Sail
• Inflation Capsule
• Capillaries
• Hardening Strips

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Frame

• 10 cm Sided Cube
• Corner Cubes Panels to be Placed on Sides

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Corner Cube Reflectors

• Flat-Plate Reflectors
• Attached to Frame
• Released Prior to Inflation
• In the Plane of the Solar Sail

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Kill Switch/Timer

• Kill Switch Triggered by Release
• Begins Timer Sequence
• Controls All Timing Sequences

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Solar Sail Properties

• Aluminized Mylar
• Circular Shape
• Area of 100 m2

Example of Aluminized Mylar Structure
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Capillaries

• Tubes attached to the surface of the solar sail
• Capillaries will be placed placed strategically
  for structural rigidity
• Tubes are inflated by nitrogen from capsule

Total Length 272 ft. Diameter 0.5 in
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Inflation Capsule

• 7.6 cm Long
• 3.8 cm Diameter
• 86 cm3 Volume
• 60.5 psi
• Placed in the Center of the CubeSat

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Hardening Strips

• Thin tape-like strips
• Strips will be placed strategically in a spider
  web pattern on the sail
• Strips harden with solar radiation exposure

Total Strip Length 308 ft.
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Cut-Away CubeSat
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Sequence of Events

• P-Pod Release/ Deactivate Kill Switch
• Waiting Period
• Side Panels Unlock
• Inflation Begins
• Inflation Ends/ Rigidization Occurs
• Solar sail reaches final shape

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Propulsion

• Taffy Tingley

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Solar Sail Material Selection
Solar Blade Solar Sail
Encounter Satellite
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Solar Sail Material Selection
Cosmos I
Star of Tolerance Satellite
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Aluminized Mylar

• High Strength to Weight Ratio
• Tested
• Cheap!
• Double Reflective

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ABAQUS
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Finite Element Design

• Monitor regions where high stress occurs
• Add tear strip or tension line to sail
• Monitor rigidity
• Model several perturbations and situations
• Perform thermal analysis
• Monitor effects of additional components
• All in 3-D

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Future Propulsion Work

• Integrate deployment apparatus into FE model
• Install Tear Strips into FE model
• Perform Thermal Analysis

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Orbit Simulation

• Paul Mears

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Solar Radiation Pressure

• Electromagnetic radiation flux
• Photon energy
• Momentum exchange produces force per unit area

?V
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Sail Thrust

• Function of T f (A, S, e, q)

where A sail area S Power (scaled Watt)
e reflectivity q angle of incidence
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Sail Thrust Vector

• Thrust Acts in the direction Normal to the Sail
• Sail Normal makes an angle q with the Sun
  Position Vector
• Thrust is generated by Incidental and Reflected
  Light

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4-Body Problem
ECEF Coordinate System (x, y, z)

• Earth (2) Sun (3) Moon
• (4) Satellite (T) Thrust

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Forces on the Satellite

• The gravitational forces of all the planets
  effect the satellite, as well as thrust

FBD Satellite
i 1, 2, 3
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Initial Conditions of Orbit

• Injection will occur at perigee
• Orbit will be highly elliptic with apogee at
  42000km

• Resulting Orbital
• Elements

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Orbit Propagation Perturbing Forces
Earth, Sun, Moon Forces
Earth Forces Only
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Orbit Propagation with Thrust
All Gravitational Forces plus Thrust
Earth, Sun, Moon Forces
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Future Work in Orbit Simulation

• Rotating Thrust Vector

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Presentation Outline
Project Overview
Management Structure
Satellite Systems
Budget
Future Work
Conclusion
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Budget

• Personnel - 15,633
• Testing - 2,000
• Materials - 5,000
• Launch - 50,000
• Total - 72,653

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Future Work

• Hardware integration
• Part size and weight definition and orientation
  within the satellite
• Deployment system timing
• Finite element analysis
• Orbital simulation
• Rotating thrust vector definition
• Orbital trajectories simulation

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Conclusion

• PaperSat is developing a picosatellite design
  for CubeSat
• Design will test solar sail propulsion technology
• Design will not incorporate attitude control
• Deployment system uses compressed gas
• Solar sail will be reflective on both sides
• Position, acceleration, and orientation will be
  measured from ground stations
• http//www.ae.utexas.edu/design/papersat/

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Acknowledgements

• Dr. Wallace Fowler
• Dr. Cesar Ocampo
• Dr. Eric Becker
• Meredith Fitzpatrick
• Previous CubeSat Design Groups

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Questions?