bi-elliptic transfers

Noun

bi-elliptic transfer (plural bi-elliptic transfers)

1. A type of movement of a spacecraft from one orbit to another, in which the spacecraft first raises its apoapsis to an extremely high altitude, then, at the new, higher, apoapsis, performs an engine burn to change its periapsis to that of the desired orbit, and, finally, upon reaching the new periapsis, performs a third burn to lower the eccentricity of its orbit and circularize in the desired orbit, or performs these steps in reverse to move from a higher to a lower orbit.