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Copernicus, A Generalized Trajectory Design and Optimization System

Copernicus, A Generalized Trajectory Design and Optimization System. Greg Johnson Sebastian Munoz The University of Texas at Austin November 25, 2003. Overview. What is trajectory design and optimization? What makes this problem so difficult?

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Copernicus, A Generalized Trajectory Design and Optimization System

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  1. Copernicus, A Generalized Trajectory Design and Optimization System Greg Johnson Sebastian Munoz The University of Texas at Austin November 25, 2003

  2. Overview • What is trajectory design and optimization? • What makes this problem so difficult? • The necessity for a generalized trajectory system • Existing systems • The Copernicus trajectory system • Conclusions

  3. Trajectory produced with Copernicus, created in SOAP by Sebastian Munoz What is trajectory design and optimization? • Finding the best trajectories for a given mission • Example: Moon Capture • Earth/Moon trajectory • Ballistic • 3rd body perturbation

  4. What makes this problem so difficult? • What is the best trajectory? • Minimized parameters • Total ΔV • Time of flight • Maximized parameters • Payload capacity • Excess fuel • Finding a trajectory with optimal values for one or all of these parameters

  5. The necessity of a general system • General • “Not limited in scope, area or application” –The American Heritage Dictionary of the English Language • Capabilities of a general system • ΔV minimization • Time of flight minimization • Payload maximization • Excess fuel maximization • Multiple segments for a trajectory • Such a system would satisfy the needs for any mission, including complex interplanetary trajectories

  6. Some other systems • VARITOP • CHEBYTOP • MIDAS • SEPSPOT • GESOP & ASTOS • Strengths and weaknesses

  7. VARITOP • “General two-body, sun-centered trajectory design and optimization program” • Low thrust trajectories only

  8. CHEBYTOP • “General two-body, sun-centered trajectory design and optimization program” • Computationally quick, but inaccurate • Quick mission planning, but future analysis required

  9. MIDAS • “Patched-conic interplanetary trajectory solver” • Minimizes ΔV and mass, not time • Difficult to use, large input files • Created to verify the validity of results from other programs

  10. SEPSPOT • Computes trajectories for electrically propelled spacecraft • Considers wide range of forces • Only minimizes time • Good for Orbital eccentricities less than .65

  11. GESOP & ASTOS • “Graphical Environment for Simulation and OPtimization” • Can simulate any dynamical system • Uses ASTOS application for spacecraft trajectory optimization • Requires large amount of input • Result accuracy may be affected by broadness of problems it can solve

  12. Inspiration • Copernicus developed to combine capabilities of other programs, without their weaknesses • Development began Fall 2001 by Dr. Cesar Ocampo

  13. Ocampo, Cesar, “An Architecture for a Generalized Spacecraft Trajectory Design and Optimization System,” The University of Texas at Austin, Austin, TX, 2003. Copernicus Trajectory System • Goals • Solve any type of trajectory problem • Initial and final states • Fixed or variable • Parameters to minimize or maximize • Any or all • Methods used • “Basic” trajectory segment

  14. Ocampo, Cesar, “An Architecture for a Generalized Spacecraft Trajectory Design and Optimization System,” The University of Texas at Austin, Austin, TX, 2003. The Trajectory Segment • Allows boundary conditions to be specified • Allows discontinuities • Fixed/free parameters • Numerical methods used to solve the problem

  15. What it can do… • 2-body transfer/rendezvous • Return trajectories • Libration point considerations • Low thrust trajectories • Gravity assists • Ballistic/low energy captures using third-body effects

  16. Conclusions • General system is necessary • Saves mission design time, and man hours • Reliable for any conceivable problem • Copernicus is the most general trajectory design and optimization system available • combines features of other programs without their weaknesses • Copernicus is still a prototype, hence there is still a lot to be done – i.e. graphical user interface, OpenGL graphics

  17. References • For more information about the trajectory systems discussed, see: • Ocampo, Cesar, “An Architecture for a Generalized Spacecraft Trajectory Design and Optimization System,” The University of Texas at Austin, Austin, TX, 2003. • http://trajectory.grc.nasa.gov/Tools • http://www.astos.de

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