raptop changed the topic of #principia to: READ THE FAQ: http://goo.gl/gMZF9H; The current version is Fréchet. We currently target 1.5.1, 1.6.1, and 1.7.x. <scott_manley> anyone that doubts the wisdom of retrograde bop needs to get the hell out | https://xkcd.com/323/ | <egg> calculating the influence of lamont on Pluto is a bit silly… | <egg> also 4e16 m * 2^-52 is uncomfortably large
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<discord-> e​gg. — @rsparkyc yeah min periapsis could definitely be useful
<discord-> e​gg. — but the rest is just conceptually very messy
<discord-> e​gg. — none of the mean elements are actual geometric properties of the orbit anymore
<discord-> e​gg. — they are sort of notional properties that vaguely feel like the elements you know
<discord-> r​sparkyc. — You have them in the map view though
<discord-> e​gg. — but a mean periapsis would have nothing to do with the minimal distance
<discord-> e​gg. — the things in the map view are not elements
<discord-> e​gg. — they are instantaneous properties
<discord-> e​gg. — "here is the point closest to the planet"
<discord-> r​sparkyc. — It would be cool to see your next, min, max, and average ap and pe
<discord-> e​gg. — a "mean periapsis" is a sort of "if this were a Keplerian orbit, its periapsis would be this", which is really useless
<discord-> e​gg. — next/mean, yes
<discord-> e​gg. — average pe, that is devoid of meaning
<discord-> e​gg. — you do not have one periapsis per orbit
<discord-> e​gg. — not in the sense of "lowest point" at least
<discord-> e​gg. — you can easily get orbits with four of those
<discord-> r​sparkyc. — That’s true
<discord-> e​gg. — and the underlying "mean" periapsis will be at none of those points
<discord-> e​gg. — and will have a different altitude altogether
<discord-> e​gg. — since people are used to thinking of the periapsis as the thing that tells them "will I bump into a planet", bring it as a mean element is very likely to mislead them into said planet
<discord-> e​gg. — mininmal distance from the central body over the mission duration is what you want for that (min of the numbers on the Pe markers)
<discord-> e​gg. — maximum of the minima is largely useless (and will run into the same issues, a sufficiently perturbed orbit might have minima of distance near its apogee for all I know)
<discord-> r​sparkyc. — What do you think about max apoapsis, maybe knowing if you’ll go out of range of comms
<discord-> r​sparkyc. — At that point, it would just be min and max altitude
<discord-> n​eph. — I could see that being useful even for halo orbits
<discord-> n​eph. — Knowing this is on average the closest from a reference body I will get per period & this is on average the furthest--is that easily analyzable?
<discord-> n​eph. — Too much thinking: jack & sunny time
<discord-> e​gg. — 𒈫𒊨𒈦
<discord-> e​gg. — maybe I should switch the keyboard back from my experimental cuneiform IME before typing English
<discord-> e​gg. — min and max distance from the primary over the mission duration sound like a good idea
<discord-> e​gg. — > Knowing this is on average the closest from a reference body I will get per period & this is on average the furthest--is that easily analyzable?
<discord-> e​gg. — Not very well defined
<discord-> e​gg. — (see the issue of multi-apsis revolutions, you cannot have something based on both "the periapsis is a thing of which there is one per revolution" and "the periapsis is a minimum of geometric distance")
<discord-> n​eph. — local extrema from the reference body?
<discord-> e​gg. — yes, those can be far
<discord-> e​gg. — you can have a local minimum near the global maximum because your orbit looks like a plate of noodles
<discord-> e​gg. — and those will mess with the local minima that you are thinking of
<discord-> e​gg. — (the Keplerian periapsides)
<discord-> e​gg. — an other way to look at this is how actionable the information is
<discord-> e​gg. — > this is on average the closest from a reference body I will get per period & this is on average the furthest
<discord-> e​gg. — What definition of this makes it useful for mission design/mission control
<discord-> e​gg. — I contend that none really do
<discord-> e​gg. — if you care about mean orbit shape, you want to constrain e
<discord-> e​gg. — if you care about not bumping into the ground or not losing contact, you want to constrain the absolute min and max distance
<discord-> n​eph. — extrema of the extrema over an arbitrary time forecast by the prognosticator?
<discord-> e​gg. — yes, see the absolute min/max
<discord-> e​gg. — (but it's not the prognosticator, please don't summon technical internals at random, the prognosticator computes the prediction and not the trajectory backing the analysis, which is much longer)
<discord-> n​eph. — Wait, there is a prognosticator in principia?
<discord-> e​gg. — yes there is a thing called the prognosticator
<discord-> e​gg. — it computes the prognostication
<discord-> n​eph. — I am drunk & verbose. That is amusing & coincidental. I'm laughing
<discord-> e​gg. — which gets swapped to replace the prediction
<discord-> e​gg. — the prognostication is the WIP prediction, if you will
<discord-> n​eph. — re: means: I think you could take extrema of the forecast (iteration 0) before approximating it/interpolating it (to taste) & recalculating those extrema of the approximation/interpolation (iteration 1). Repeat until changes are within some epsilon (probably defined as a function of e & distance from ref. body)
<discord-> e​gg. — (that was introduced when prediction computation became asynchronous rather than blocking)
<discord-> n​eph. — Brilliantly named. Will file that for future reference
<discord-> e​gg. — I think you are trying to reinvent mean elements
<discord-> n​eph. — yes
<discord-> n​eph. — I should probably stop
<discord-> e​gg. — the thing is you can compute a thing which is a notional mean periapsis
<discord-> e​gg. — in fact you can compute it from what we give already
<discord-> e​gg. — you have the mean a and mean e, and I think a reasonable mean pe would be computed from those
<discord-> n​eph. — That would be simpler, yes
<discord-> e​gg. — (mean e is actually computed by averaging {e sin (Ω+ω+M), e cos (Ω+ω+M)} rather than e, because that is much more natural and works with low-eccentricity & equatorial orbits)
<discord-> e​gg. — (so computing mean pe from other mean elements would not be that outlandish)
<discord-> n​eph. — & how does it work in halo?
<discord-> e​gg. — it fails
<discord-> n​eph. — Or otherwise in cases where the reference body = the point orbited
<discord-> e​gg. — I think in loosely bound orbits the analyzer will simply say it is not Keplerian
<discord-> n​eph. — Or otherwise in cases where the reference body != the point orbited (edited)
<discord-> e​gg. — and thus there is nothing to analyze
<discord-> e​gg. — it only analyzes elliptic orbits, because it needs to average over a revolution
<discord-> n​eph. — I see. I return to my former position: mean minima & mean maxima distance from an arbritary reference body would be useful
<discord-> n​eph. — I see. I return to my former position: mean minima & mean maxima of distance from an arbritary reference body would be useful (edited)
<discord-> e​gg. — in what way is that actionable
<discord-> e​gg. — a mean pe computed from the mean elements is a different way to look at e, and as such gives you an idea of the orbit shape & size
<discord-> e​gg. — in that sense it is useful
<discord-> n​eph. — Reference from earth: communications. Reference from sun: panel insolation. Reference from orbiting relay no. 199: more communications
<discord-> e​gg. — but I will not give it, because it misleads you as to what Pe means compared to the Pe markers that are a geometric property
<discord-> e​gg. — > Reference from earth: communications. Reference from sun: panel insolation. Reference from orbiting relay no. 199: more communications
<discord-> e​gg. — So then you want maxima, or maybe percentiles, definitely not the mean
<discord-> n​eph. — Rename to "mean min/maximum distance from point"
<discord-> n​eph. — Perhaps
<discord-> n​eph. — Extrema are more unstable than averages though
<discord-> e​gg. — I have to deal with the fact that people know, or think they know, things, I cannot wipe their minds
<discord-> e​gg. — Pe is deeply ingrained as the marker you check to see if you bump into the ground
<discord-> n​eph. — Perhaps having 99% uplink is worth having in cases where 100% is extremely difficult to obtain?
<discord-> n​eph. — These are hypotheticals. I have not yet turned to the analyzer for such situations
<discord-> e​gg. — hence:
<discord-> e​gg. — > So then you want maxima, or maybe percentiles, definitely not the mean
<discord-> n​eph. — No: maxima, perhaps: percentiles.
<discord-> e​gg. — well
<discord-> e​gg. — extrema are also useful
<discord-> e​gg. — if the absolute lowest altitude is below the terrain, you want to know that
<discord-> e​gg. — it doesn't matter if it's above the terrain for 99% of the mission :-)
<discord-> S​kylar. — btw, nice job on the update! thank you. I am really enjoying better rotation lol
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<discord-> n​eph. — That is true. I am thinking more detached applications. eg.: distances from a given point some altitude above surface. see geosynchronous.
<discord-> n​eph. —
<discord-> n​eph. — upon reflection I believe mean omega would serve the same purpose. Hmm.
<discord-> n​eph. — Perhaps you are right that this use case is too niche.
<discord-> e​gg. — yeah then we are definitely past the realm of general orbit properties if this involves points other than the primary
<discord-> e​gg. — I mean, the ground track analysis section goes into things of that flavour a bit
<discord-> n​eph. — One more stab: I have a relay in earth-sol L4. I have a cycler from venus to mars. What % of time will it be in comms range.
<discord-> n​eph. — Yes, my intentions are def. outside of gen. orbit props.
<discord-> e​gg. — yeah, this is entirely outside the scope of orbit analysis
<discord-> n​eph. — I can respect a firm scope limitation
<discord-> n​eph. — thanks for the repostes. back to iasip
<discord-> n​eph. — thanks for the ripostes. back to iasip (edited)
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<discord-> e​gg. — OK I need to learn Chinese apparently https://forum.kerbalspaceprogram.com/index.php?/topic/162200-wip151-161-17x-181-principia%E2%80%94version-frobenius-released-2020-03-24%E2%80%94n-body-and-extended-body-gravitation-axial-tilt/page/60/&tab=comments#comment-3760868
<discord-> S​kylar. — btw, egg, thanks for this update, it is really awesome! in mission reports you can see the device I am using to test it
<discord-> e​gg. — Does someone here speak Chinese so that I may draft a cogent reply ?
<discord-> S​kylar. — frobenius is very cool. thank you. I have been testing a small probe with two metal balls on stick and IR parts to move them inwards or outwards to see how it interects, you can see that in mission reports.
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<discord-> n​eph. — Two balls on a stick eh
<discord-> S​kylar. — @neph lol yeah, I posted it onto mission reports, I have been just messing with it to test all the details of it with timewarp, and seems to work great
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<discord-> S​kylar. — Btw, egg, are you planning on ever adding a persisent thrust to principia almost how you added an essentially peristent rotation?
<egg|cell|egg> That is a very different problem
<egg|cell|egg> Requires interacting with the game in entirely new ways, understanding engines and fuel
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<discord-> n​eph. — https://youtu.be/f_w6JprsXK8
<kmath> YouTube - Three-body problem sonified
<_whitenotifier-d13c> [Principia] KouroshSimpkins starred Principia - https://git.io/JvSVn
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<_whitenotifier-d13c> [Principia] Growflavor commented on issue #2457: Keep track of the vessels when they are managed by KSP - https://git.io/JvSDt
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