In astrodynamics, orbit phasing is the adjustment of the time-position of spacecraft along its orbit, usually described as adjusting the orbiting spacecrafts true anomaly. Orbital phasing is primarily used in scenarios where a spacecraft in a given orbit must be moved to a different location within the same orbit. The change in position within the orbit is defined as the phase angle, ϕ. To gain or lose time, the spacecraft must be subjected to a simple two-impulse Hohmann transfer which takes the spacecraft away from. The first impulse to change the orbit is performed at a specific point in the original orbit. The impulse creates a new orbit called the “phasing orbit” and is larger or smaller than the original orbit resulting in a different period time than the original orbit. The difference in time between the original and phasing orbits will be equal to the time converted from the phase angle. When complete, the spacecraft will be in the final position within the original obit. To find some of the orbital parameters, first one must find the required period time of the phasing orbit using the following equation. Total change of velocity required for the maneuver is equal to two times ∆V. Orbit phasing can also be referenced as co-orbital rendezvous like an approach to a space station in a docking maneuver. Orbital maneuver Docking maneuver Hohmann transfer orbit General Curtis, Howard D, sellers, Jerry Jon, Marion, Jerry B. Understanding Space An Introduction to Astronautics, http, //arc. aiaa. org/doi/pdf/10. 2514/2.6921 Minimum-Time Orbital Phasing Maneuvers - AIAA, CD Hall -2003 Phasing Maneuver
Image: Phase angle
If the target (satellite) is behind the spacecraft (shuttle) in the same orbit, the spacecraft must speed up to enter a larger, slower phasing orbit to allow the target to catch up.
If spacecraft is behind the final position on the same orbit, the spacecraft must slow down to enter a smaller, faster phasing orbit to catch up to final position.