# How are B-Plane parameters actually determined for a planetary flyby?

Reading from this document, I am trying to simulate the New Horizons probe trajectory in GMAT and I am puzzled with how the authors of the original paper (by legendary mission designer Robert W. Farquhar and Yanping Guo) got the B-Plane parameters for the Jupiter flyby.

From the original paper the correct B-Plane parameters for the Jupiter flyby should be

What techniques do they use to actually derive the correct Fly-by parameters? Is there any method that I can use in GMAT to arrive at those actual parameters? One method that I can think of is using the Optimization module in GMAT but I am not sure If that is the correct route.

• Neither This nor this answer about Juno answers your question but you might find something there helpful.
– uhoh
Nov 11, 2020 at 22:27
• @uhoh actually, I think the answer is in the NASA tech report linked from there. The choice has to be flexible, because the plane in which the spacecraft travels depends in part on the location and time of day of the launch., as the tech report graphs in many different ways. Nov 24, 2021 at 21:11
• Typically, mission designers will design the mission "backward" from the final desired orbit all the way back to launch date. For example, if you have an orbiter whose goal is to map out the celestial body from latitude +/- 80 degrees over X days, then the orbit will be optimized to meet that. Then, build the interplanetary trajectory by converting that orbit to a hyperbolic heliocentric orbit and computing the B-plane. If the maneuver is too large, find an insertion orbit different from the science orbit and compute the dv needed to make sure you're still within the fuel budget. Nov 24, 2021 at 22:38