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When playing e.g. the Rosetta mission in Kerbal Space Program (KSP), one of the things one can achieve is called Orbit Accuracy.

Unfortunately, after searching KSP's forums and Wiki I still can not find any answer to the question: What exactly is this Orbit Accuracy and how is it defined/calculated? Is this based on reality? Especially the percentage nature of this value makes it difficult to interpret for me.

user40799
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Kreuvf
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    This seems like a gameplay-specific question, and the best place to ask would probably be the official Gameplay Questions and Tutorials. board on the official KSP forums.. The Arqade Stack Exchange at https://gaming.stackexchange.com/ would be another option. – notovny Jul 04 '21 at 20:38
  • @notovny yes, while some KSP questions here are well received (What can the KSP game actually teach about spaceflight and orbital mechanics, and what are its limitations?, Are patched conics (and by induction, KSP) “useless” for simulating ion propulsion?) Does Kerbal Space Program have a software migration path to Lagrange points, halo orbits, and other 3-body goodies? and several others... – uhoh Jul 05 '21 at 00:10
  • one had some pushback: Are Jool's moons' orbits stable?. See my comments there about other specific KSP questions that were well received here and answered. The answer for Jool's moons related to numerical simulation: "Principia, an n-body gravitational implementation" and resulted in the next question How would an n-body numerical orbit simulator use hierarchy in its Jacobian?. I think a question about orbital accuracy of a simulation is on-topic here. I have a hunch this will be answered. – uhoh Jul 05 '21 at 00:16
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    @Kreuvf I think this is fine here and may also be fine in Arqade as well. I updated your title to match your question and to emphasize its orbital mechanical nature, and posted a link in the Arquade chat room. – uhoh Jul 05 '21 at 00:24
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    @uhoh I don't think this question is about how accurate orbits are in Kerbal Space Program. I think this question is about how the "Orbit Accuracy" score is calculated when playing scenarios in the "Making History" expansion for Kerbal Space Program. – notovny Jul 05 '21 at 00:24
  • @notovny it's about the direct relationship between an accuracy setting and the actual mathematical accuracy of a calculation. The question about Jool's moon's numerical stability turned out to have quite an interesting and on-topic answer despite worries to the contrary, let's see what answers are forthcoming here. – uhoh Jul 05 '21 at 00:29
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    This question would be fine on Arqade, as I'm pretty sure it is a gameplay question. IIRC, it can be a requirement for certain contracts, requiring your orbital parameters to be within the defined limits. – MBraedley Jul 05 '21 at 00:31
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    No, this is about an accuracy figure that's specific to the game. If it were about how KSP defines "eccentricity" or something, that would be on-topic. – Russell Borogove Jul 05 '21 at 02:10
  • If KSP is closed source, and they don't mention in the documentation, the formula used for calculating this parameter, then, only the developer can answer this question (definitively) I think. – AJN Jul 05 '21 at 02:34
  • OP, is it a setting or something the player has to achieve? IMO, I interpret both in slightly different ways. In the former, I interpret it as changing the orbital propagation/integration scheme of the simulator. The latter as the difference between the mission orbital parameter target and player achieved target (e.g. apoapsis_target - apoapsis_achived). – AJN Jul 05 '21 at 02:38
  • @AJN "only the developer can answer this question" see my several links in comments above; there is plenty of information available about the inner workings of the numerical algorithms in KSP. Predictions of the type "nobody can answer this" may be premature. – uhoh Jul 05 '21 at 23:16
  • make sure your apoapsis and periapsis are both within that percentage of the values specified in the contract/mission – user40799 Jul 06 '21 at 09:26
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    Please leave this open until there is an answer. If the setting is about how accurate the computational model is to reality, then it is on-topic for Space.SE. If the setting is instead about getting an achievement for playing "accurately", then it is off-topic for Space.SE and should be migrated to Arquade. We simply won't know which is the case until there is an answer. – DrSheldon Jul 07 '21 at 04:09
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    I disagree with that reasoning. Clarifying what's being asked is something that should be done in the question. Questions can be reopened if it can be made clear that they are on-topic. – SE - stop firing the good guys Jul 11 '21 at 08:16
  • @AJN KSP is implemented in C#, and it turns out to be very straightforward to decompile C#'s compiled bytecode back to source. Even if it weren't, the community surrounding KSP is entirely capable of doing the in-game experiments needed to reverse-engineer the algorithm, and probably has already. – Russell Borogove Jul 11 '21 at 17:12

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All you need to do is make sure your apoapsis, periapsis, and inclination are both within that percentage of the values specified in the contract/mission.

You can find the current values for these in the tracking centre, and creating a manoeuvrer node will allow you to see how different thrusts will change your orbit.

So, if the mission parameters say you have to be within 10% of a 125 x 340 km orbit with an inclination of 45 degrees, your periapsis needs to be between 113km and 137 km, etc.

user40799
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