Porkchop plot

, vertical axis: arrival dates (mm/dd)) A given blue contour represents a solution with a constant C 3 . The center of the porkchop is the optimal solution for the lowest C 3 . The red lines represent trips with the same travel time for the trajectory. The green lines represent the Sun-Earth-Probe angle upon departure. In orbital mechanics, a porkchop plot (also pork-chop plot) is a chart that shows level curves of equal characteristic energy (C 3 ) against combinations of launch date and arrival date for a particular interplanetary flight. The chart shows the characteristic energy ranges in zones around the local minima, which resembles the shape of a porkchop slice. By examining the results of the porkchop plot, engineers can determine when a launch opportunity exists (a 'launch window') that is compatible with the capabilities of a particular spacecraft. A given contour, called a porkchop curve, represents constant C 3 , and the center of the porkchop the optimal minimum C 3 . 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).

, vertical axis: arrival dates (mm/dd)) A given blue contour represents a solution with a constant C 3 . The center of the porkchop is the optimal solution for the lowest C 3 . The red lines represent trips with the same travel time for the trajectory. The green lines represent the Sun-Earth-Probe angle upon departure. ]] In orbital mechanics, a porkchop plot (also pork-chop plot) is a chart that shows level curves of equal characteristic energy (C 3 ) against combinations of launch date and arrival date for a particular interplanetary flight. The chart shows the characteristic energy ranges in zones around the local minima, which resembles the shape of a porkchop slice. By examining the results of the porkchop plot, engineers can determine when a launch opportunity exists (a 'launch window') that is compatible with the capabilities of a particular spacecraft. A given contour, called a porkchop curve, represents constant C 3 , and the center of the porkchop the optimal minimum C 3 . 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). C_3 = v_\infty^2\,\! where v_\infty \, is the orbital velocity when the orbital distance tends to infinity. Note that, since the kinetic energy is \frac{1}{2}mv^2 , C 3 is in fact equal to twice the magnitude of the specific orbital energy, \epsilon , of the escaping object. ==See also== Orbit Parabolic trajectory Hyperbolic trajectory ==References== ==External links== JPL Introduction to Porkchop plots Pork-chop plot online computation tool

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