Orbital Mechanics: The Fundamentals

Space is not just high up; it is moving very fast horizontally. Getting to orbit requires immense velocity.

An orbit is simply a trajectory where an object's forward velocity is sufficient that the curve of its fall matches the curvature of the planet below.

The Six Orbital Elements

• Semi-major Axis (a): The size of the orbit.
• Eccentricity (e): The shape of the orbit (0 = circular).
• Inclination (i): The tilt relative to the equator.
• Right Ascension of the Ascending Node (Ω): The swivel of the orbital plane.
• Argument of Periapsis (ω): The orientation of the ellipse.
• True Anomaly (ν): The position of the spacecraft right now.

Changing inclination in orbit requires immense amounts of propellant, which is why launch site latitude dictates what orbits can be reached efficiently.