Trajectory Analysis
These are some notes from a lecture by Helge Eichhorn
What is Space Mission Design?
- Determining how a spacecraft will reach its target orbit (efficient, reasonable amount of time and not break the laws of physics)
Definition of State Vectors
- : Position vector
- : Velocity vector
- : Epoch e.g. in Julian days
- Cooridnate frame
- Central body (e.g. gravitational parameter )
Determination of Keplerian Orbital Elements
- Shape of the orbital ellipse (or other conic section):
- : Semi-major axis
- : Eccentricity
- Orientation of the orbital plane:
- : inclination
- : Longitude of the ascending node
- Orientation of the orbital ellipse within the orbital plane
- : Argument of periapsis
- Position of the orbiting body on the orbital ellipse at a given point:
- : True anomaly
Solving Kepler's Equation
Paraphrasing Kepler's Second Law:
- The radius vector sweeps equal areas in equal fractions of time
- Umkreis = Circumcircle
- : Mean anomaly - angle at the center sweeping the circumcircle of the orbit
- : Eccentric anomaly - angle at the center sweeping the orbital ellipse
- : True anomaly - angle at the focus sweeping the orbit ellipse