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Solar Sail. Department of Aerospace Engineering and Mechanics AEM 4332W – Spacecraft Design Spring 2007. Team Members. Solar Sailing:. Project Overview. Design Strategy. Trade Study Results. Orbit. Eric Blake Daniel Kaseforth Lucas Veverka. Eric Blake.

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solar sail

Solar Sail

Department of Aerospace Engineering and Mechanics

AEM 4332W – Spacecraft Design

Spring 2007

orbit

Orbit

Eric Blake

Daniel Kaseforth

Lucas Veverka

eric blake

Eric Blake

Optimal Trajectory of a Solar Sail: Derivation of Feedback Control Laws

recall orbital mechanics
Recall Orbital Mechanics
  • The state of a spacecraft can be described by a vector of 6 orbital elements.
    • Semi-major axis, a
    • Eccentricity, e
    • Inclination, i
    • Right ascension of the ascending node, Ω
    • Argument of perihelion, ω
    • True anomaly, f
  • Equivalent to 6 Cartesian position and velocity components.
equations of motion
Equations of Motion

= Sail Lightness Number

= Gravitational Parameter

problem minimize transfer time
Problem: Minimize Transfer Time

By Inspection:

Transversality:

solution
Solution
  • Iterative methods are needed to calculate co-state boundary conditions.
  • Initial guess of the co-states must be close to the true value, otherwise the solution will not converge.
  • Difficult
  • Alternative: Parameter Optimization.
    • For given state boundary conditions, maximize each element of the orbital state by an appropriate feedback law.
orbital equations of motion
Orbital Equations of Motion

= Sail Lightness Number

= Gravitational Parameter

maximizing solar force in an arbitrary direction
Maximizing solar force in an arbitrary direction

Maximize:

Sail pointing for maximum acceleration in the q direction:

locally optimal trajectories
Locally Optimal Trajectories
  • Example: Use parameter optimization method to derive feedback controller for semi-major axis reduction.
  • Equations of motion for a:

Feedback Law:

Use this procedure for all orbital elements

method of patched local steering laws lsl s
Method of patched local steering laws (LSL’s)
  • Initial Conditions: Earth Orbit
  • Final Conditions: semi-major axis: 0.48 AU inclination of 60 degrees
global optimal solution
Global Optimal Solution
  • Although the method of patched LSL’s is not ideal, it is a solution that is close to the optimal solution.
  • Example: SPI Comparison of LSL’s and Optimal control.
conclusion
Conclusion
  • Continuous thrust problems are common in spacecraft trajectory planning.
  • True global optimal solutions are difficult to calculate.
  • Local steering laws can be used effectively to provide a transfer time near that of the global solution.
lucas veverka

Lucas Veverka

Temperature

Orbit Implementation

daniel kaseforth

Daniel Kaseforth

Control Law Inputs and Navigation System

structure
Structure

Jon T Braam

Kory Jenkins

jon t braam
Jon T. Braam

Structures Group:

Primary Structural Materials

Design Layout

3-D Model

Graphics

primary structural material
Primary Structural Material

Weight and Volume Constraints

  • Delta II : 7400 Series
  • Launch into GEO
    • 3.0 m Ferring
      • Maximum payload mass: 1073 kg
      • Maximum payload volume: 22.65 m3
    • 2.9 m Ferring
      • Maximum payload mass: 1110 kg
      • Maximum payload volume: 16.14 m3
primary structural material1
Primary Structural Material

Aluminum Alloy Unistrut

  • 7075 T6 Aluminum Alloy
    • Density
      • 2700 kg/m3
      • 168.55 lb/ft^3
    • Melting Point
      • ? Kelvin

Picture of Unistrut

primary structural material2
Primary Structural Material
  • Density
  • Mechanical Properties
    • Allowing unistrut design
      • Decreased volume
  • Thermal Properties
    • Capible of taking thermal loads
design layout
Design Layout
  • Constraints
    • Volume
    • Service task
    • Thermal consideration
    • Magnetic consideration
    • Vibration
    • G loading
design layout1
Design Layout
  • Unistrut Design
    • Allowing all inside surfaces to be bonded to
      • Titanium hardware
    • Organization
      • Allowing all the pointing requirements to be met with minimal attitude adjustment
design layout2
Design Layout
  • Large Picture of expanded module
3 d model
3-D Model
  • Large picture
3 d model1
3-D Model
  • Blah blah blah (make something up)
graphics
Graphics
  • Kick ass picture
graphics1
Graphics
  • Kick ass picture
trade studies
Trade Studies
  • Blah blah blah
why i deserve an a
Why I deserve an “A”
  • Not really any reason but when has that stopped anyone!
kory jenkins
Kory Jenkins

Sail Support Structure

Anticipated Loading

Stress Analysis

Materials

Sail Deployment

attitude determination and control

Attitude Determination and Control

Brian Miller

Alex Ordway

brian miller

Brian Miller

Tip Thrusters vs. Slidnig Mass

Attitude Control Simulation

alex ordway 60 hours worked

Alex Ordway60 hours worked

Attitude Control Subsystem Component Selection and Analysis

design drivers
Design Drivers
  • Meeting mission pointing requirements
  • Meet power requirements
  • Meet mass requirements
  • Cost
  • Miscellaneous Factors
trade study
Trade Study
  • Sliding Mass vs. Tip Thruster Configuration
    • Idea behind sliding mass
trade study1
Trade Study
  • Sliding mass ACS offers
    • Low power consumption (24 W)
    • Reasonable mass (40 kg)
    • Low complexity
    • Limitations
      • Unknown torque provided until calculations are made
      • No roll capability
  • Initially decided to use combination of sliding mass and tip thrusters
adcs system overview
ADCS System Overview
  • ADS
    • Goodrich HD1003 Star Tracker primary
    • Bradford Aerospace Sun Sensor secondary
  • ACS
    • Four 10 kg sliding masses primary
      • Driven by four Empire Magnetics CYVX-U21 motors
    • Three Honeywell HR14 reaction wheels secondary
    • Six Bradford Aero micro thrusters secondary
      • Dissipate residual momentum after sail release
slide50
ADS
  • Primary
    • Decision to use star tracker
      • Accuracy
      • Do not need slew rate afforded by other systems
    • Goodrich HD1003 star tracker
      • 2 arc-sec pitch/yaw accuracy
      • 3.85 kg
      • 10 W power draw
      • -30°C - + 65 °C operational temp. range
      • $1M
    • Not Chosen: Terma Space HE-5AS star tracker
slide51
ADS
  • Secondary
    • Two Bradford Aerospace sun sensors
      • Backup system; performance not as crucial
      • Sensor located on opposite sides of craft
      • 0.365 kg each
      • 0.2 W each
      • -80°C - +90°C
slide52
ACS
  • Sliding mass system
    • Why four masses?
    • Four Empire Magnetics CYVX-U21 Step Motors
      • Cryo/space rated
      • 1.5 kg each
      • 28 W power draw each
      • 200°C
      • $55 K each
      • 42.4 N-cm torque
slide53
ACS
  • Gear matching- load inertia decreases by the gear ratio squared. Show that this system does not need to be geared.
slide54
ACS
  • Three Honeywell HR14 reaction wheels
    • Mission application
    • Specifications
      • 7.5 kg each
      • 66 W power draw each (at full speed)
      • -30ºC - +70ºC
      • 0.2 N-m torque
      • $200K each
      • Not selected
        • Honeywell HR04
        • Bradford Aerospace W18
slide55
ACS
  • Six Bradford micro thrusters
    • 0.4 kg each
    • 4.5 W power draw each
    • -30ºC - + 60ºC
    • 2000 N thrust
    • Supplied through N2 tank
attitude control
Attitude Control
  • Conclusion
    • Robust ADCS
      • Meets and exceeds mission requirements
      • Marriage of simplicity and effectiveness
      • Redundancies against the unexpected
power thermal and communications

Power, Thermal and Communications

Raymond Haremza

Michael HitiCasey Shockman

raymond haremza

Raymond Haremza

Thermal Analysis

Solar Intensity and Thermal Environment

Film material

Thermal Properties of Spacecraft Parts

Analysis of Payload Module

Future Work

casey shockman

Casey Shockman

Communications

acknowledgements
Acknowledgements
  • Stephanie Thomas
  • Professor Joseph Mueller
  • Professor Jeff Hammer
  • Dr. Williams Garrard
  • Kit Ru….
  • ?? Who else??
ad