🔗 Porkchop plot

A porkchop plot (also pork-chop plot) is a chart that shows contours of equal characteristic energy (C₃) against combinations of launch date and arrival date for a particular interplanetary flight.

By examining the results of the porkchop plot, engineers can determine when launch opportunities exist (a launch window) that is compatible with the capabilities of a particular spacecraft. A given contour, called a porkchop curve, represents constant C₃, and the center of the porkchop the optimal minimum C₃. The orbital elements of the solution, where the fixed values are the departure date, the arrival date, and the length of the flight, were first solved mathematically in 1761 by Johann Heinrich Lambert, and the equation is generally known as Lambert's problem (or theorem).