Six Words
Six Words
[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.

The six words are: "It works in Kerbal Space Program ".
The Kuiper Belt is a region of the outer Solar System beyond the orbit of Neptune consisting of numerous small icy bodies, including the dwarf planets Pluto and Eris . An Oberth maneuver is a spaceflight maneuver, specifically an engine burn performed during the flyby of a celestial body. The point of this is to optimize usable energy, because rocket burns are more effective to perform at high speeds than at low speeds. The more massive the body and the lower the altitude, the higher the flyby speed will be, and the greater the performance gain due to the Oberth effect. The theoretical way to use rocket fuel most efficiently is therefore to execute the burn during a flyby of the most massive celestial body available, as close as possible.
Cueball is proposing to implement an "Oberth Kuiper Maneuver", and the proposal diagram shows the spacecraft using gravity assists to travel first towards (presumably) Venus for a first boost, then towards Jupiter for another swing by, aiming it back towards the Sun , the most massive Solar System body, to perform an Oberth maneuver at the point of closest approach, as indicated by a small dot along the spacecraft trajectory. It is possible that the diagram might only be a simplified outline of a more complex flight plan. For example, the trajectory from Earth to Venus would require two separate burns in deep space. The first burn would occur immediately after escaping Earth's sphere of influence. The second burn would occur about halfway to Venus. Alternatively, Cueball may have gotten it wrong, or Randall may simply not have concerned himself with such things for the purpose of a webcomic sketch.
An Oberth maneuver in the close vicinity of the Sun, while theoretically possible and extraordinarily effective at the speeds the spacecraft would reach, would however be very difficult to carry out in real life, because the neighborhood of the Sun is an extremely hostile environment [ citation needed ] and the spacecraft could be incinerated during a too-close flyby.
Cueball's argument for why the maneuver will work in real life is that it works in Kerbal Space Program (KSP), a sandbox spaceflight simulator game. While KSP does simulate a lot of the physics of space flight, it is (necessarily) simplistic in its modeling of orbital dynamics. For example, KSP does not do any N-body simulations , so if one were flying a rocket from Earth to the moon, in the game the rocket would only be affected by Earth's gravity until it reaches a certain point where it will only be affected by the moon's gravity, unlike in real life where the rocket would feel the effects of both celestial bodies at all times. Therefore, orbits modeled using KSP would poorly reflect the actual orbital behavior of a probe traveling through the solar system on a multi-year mission involving multiple fly-by maneuvers.
Another reason why using KSP would not inspire confidence is that many players playing the game use a 'trial-and-error' method, field testing designs and inevitably either crashing them or running out of fuel stranding the craft in deep space. Inside a game this is not a major issue as one can simply reload an earlier save with no repurcussions, but in real life this would result in expensive costs constructing new spacecraft and even loss of human life, which NASA would likely frown on.
The humor in referencing KSP in the comic lies in using a simple game program to simulate complex space missions which in reality take a great number of experts to plan and implement. Fly-by maneuvers, used to minimize the fuel needed to reach a destination, need to be very carefully timed - often to within seconds - so the use of Kerbal Space Program to simulate them isn't a good enough argument for NASA to agree to implement the proposal, and implies simplistic thinking on the part of the proposer; therefore one should not say it at NASA.
The title text refers to Orbiter , which is another spaceflight simulator program. The title text suggests that the argument doesn't work for NASA, not because it's not scientifically sound, but because NASA relies on the Orbiter simulator rather than the Kerbal simulator (although the proposed maneuver would appear to work in both).
[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.
