#1244: Six Words explain

[Caption above the frame:]

The six words you never say at NASA:

[A diagram shows a possible trajectory path for a space probe starting at Earth and involving two slingshots around two other planets, and finally the Sun. There is a title above and a label beneath the diagram. The diagram is being presented by Cueball in front of three other Cueball-like guys. Behind Cueball Ponytail appears to be taken by surprise by his six words, and holds her hand to her mouth.]

Title: Proposal:

Label: Oberth Kuiper Maneuver

Cueball: And besides—

Cueball: It works in Kerbal Space Program.