Orbital Mechanics Expert

Orbital Mechanics Expert

Before Starting

1. Earth orbit or interplanetary trajectory?
2. Mission design or operations focus?
3. Impulsive or low-thrust maneuvers?

Core Expertise Areas

Keplerian Orbits

Six orbital elements: semi-major axis, eccentricity, inclination, RAAN, argument of perigee, true anomaly. Vis-viva equation: v squared = GM times 2 over r minus 1 over a. Orbital period: T = 2 pi sqrt a cubed over GM. Orbit types: circular, elliptical, parabolic, hyperbolic based on eccentricity. Specific energy: epsilon = minus GM over 2a, negative for bound orbits.

Orbital Maneuvers

Hohmann transfer: minimum energy transfer between circular orbits, two burns. Delta-V: velocity change required for maneuver, determines propellant mass. Plane change: expensive maneuver, best done at low velocity near apogee. Bielliptic transfer: three burns, more efficient than Hohmann for large ratio orbits. Phasing orbit: adjust timing for rendezvous by changing orbital period.

Rendezvous and Proximity

Clohessy-Wiltshire equations: relative motion near circular reference orbit. V-bar approach: approach along velocity vector, passive abort safe. R-bar approach: approach along radial direction, natural drift used. Hold points: stable relative positions for inspection before docking.

Perturbations

J2 effect: Earth oblateness causes nodal regression and perigee rotation. Atmospheric drag: lowers perigee, causes orbit decay for LEO satellites. Solar radiation pressure: significant for large area-to-mass ratio spacecraft. Third body: Moon and Sun perturb high Earth orbits.

Best Practices

• Use high-fidelity propagator for mission planning not just two-body model
• Include delta-V margins for navigation errors and perturbations
• Check launch window constraints for planetary missions
• Verify ground track and coverage for Earth observation missions

Common Pitfalls

Related Skills

• astrodynamics-expert
• spacecraft-design-expert
• propulsion-expert