egg changed the topic of #principia to: Logs: https://esper.irclog.whitequark.org/principia | <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…
<queqiao-> ⟨Starmincer⟩ I have one (which might be the one being referenced).
<queqiao-> I don't use it so code rot has probably set in.
<queqiao-> Some notes:
<queqiao-> Direct ascent sucks.
<queqiao-> It was always a bit twitchy and hard to nail an exact solution with.
<queqiao-> ⟨Unofficial Aesthetic Inspector⟩ Well unfortunately for me Direct Ascent is the only solution
<queqiao-> ⟨Unofficial Aesthetic Inspector⟩ what's the specific .ks
<queqiao-> ⟨the rocket science kid⟩ polar direct ascent.ks in boot folder of the repo
<queqiao-> ⟨the rocket science kid⟩ it runs two other scripts and then ends, and those probably rely on other libraries, so best install the whole package.
<queqiao-> ⟨egg⟩ This discussion seems to have veered into the land of #script-automation . We now return to our regularly scheduled cats.
<raptop> Have you tried giving the cats a copy of K&R to read?
<_whitenotifier-1adf> [Principia] eggrobin opened pull request #3676: Benchmark PlotMethod3, not PlotMethod2. - https://github.com/mockingbirdnest/Principia/pull/3676
_whitelogger has joined #principia
<_whitenotifier-1adf> [Principia] eggrobin closed pull request #3676: Benchmark PlotMethod3, not PlotMethod2. - https://github.com/mockingbirdnest/Principia/pull/3676
<queqiao-> ⟨night_beast⟩ what is this phenomenon where sats tend to be pulled towards the poles?
<raptop> Is it my imagination, or is the eccentricity also decreasing?
<queqiao-> ⟨egg⟩ ⟪night_beast⟫ what is this phenomenon where sats tend […] ⮪ Can we get a report from the orbit analyser?
<queqiao-> ⟨egg⟩ The inclination is not changing much—nor, to raptop’s comment, is the eccentricity—; what you are seeing in that picture is probably the nodal (and what raptop is seeing is probably the apsidal precession).
<queqiao-> ⟨night_beast⟩ in english? I'm still getting use to principea terms
<paculino> Tilt and ovalness are not changing much. Where it is pointing is changing.
<queqiao-> ⟨egg⟩ That was english, and those are not Principia terms, they are astronomy terms.
<queqiao-> ⟨egg⟩ But yes, the plane of the orbit is changing (though keeping a constant inclination to the equator), and where the highest point is on that plane is also changing (at a different rate)
<raptop> I guess if you want non-english, 古在メカニズムではありません
<paculino> Is Principia getting a Japanese translation?
<queqiao-> ⟨egg⟩ As raptop is alluding to, there are cases where the inclination and eccentricity both change (the Лидов–古在 mechanism, which would probably kick in for much higher orbits than yours), so it is useful to look at the analyser to see what kind of change is happening.
<queqiao-> ⟨patrikcath⟩ ⟪night_beast⟫ what is this phenomenon where sats tend […] ⮪ I vaguely remember hearing about an effect where objects are very slowly pulled into more equatorial orbits. Not sure what exactly caused it, off the top of my head I'd guess it has something to do with there being more matter around the equator
<queqiao-> ⟨egg⟩ (And should you want English transliterations of Лидов and 古在: Lidov and Kozai, respectively)
<queqiao-> ⟨egg⟩ ⟪paculino⟫ Is Principia getting a Japanese […] ⮪ Not unless someone puts in the bulk of the work, same as any other language. We can help with digging up specific terminology and random I18N trickiness, but we are not going to translate the whole thing into a language we do not speak.
<queqiao-> ⟨night_beast⟩ so is this because my orbit wasn't _exactly_ to the same inclination of my launch site? Am I seeing where the orbits are over the earth, and not the orbit relative to the center of the earth? EX: if I launched at the 50 some degree of the space station would I see the wave I'm used to seeing on station missions?
<queqiao-> ⟨egg⟩ ⟪night_beast⟫ so is this because my orbit wasn't […] ⮪ This has nothing to do with anything being exact. Your inclination, whatever you wanted it to be, is practically not changing, see the analyser report you sent.
<queqiao-> ⟨egg⟩ It is just that _while remaining at the same inclination_, the plane of your orbit changes over time.
<queqiao-> ⟨Al₂Me₆⟩ (I wonder if it's time to polish up the translation of that 百度 wiki article that I made...)
<queqiao-> ⟨egg⟩ Might be useful to link it, at least.
<queqiao-> ⟨egg⟩ Not unless someone puts in the bulk of […] ⮪ (To be honest, even in a language we do speak: we never did Italian nor German. Someone putting in the work also shows that there is interest.)
<queqiao-> ⟨Al₂Me₆⟩ (Casually glossing over the fact that they speak four languages...)
<paculino> I thought raptop's "if you want non-English" message might have been alluding to something I missed.
<queqiao-> ⟨FlapJackSlap⟩ ⟪night_beast⟫ what is this phenomenon where sats tend […] ⮪ iirc the equator of the earth has slightly more mass due to the rotation of the planet, making it have more gravity and pull orbits around it over time, it's how sun synchronous orbits work as well
<queqiao-> ⟨FlapJackSlap⟩ This is modeled in principia
<queqiao-> ⟨egg⟩ ⟪night_beast⟫ so is this because my orbit wasn't […] ⮪ To put it another way, albeit with more Greek letters and pretty pictures and less English: In this figure, your ω and Ω are changing, not your i.
<raptop> paculino: mostly siliness at the complain of asking for English language astronomical terms to be translated into english, and covering the missing thing (kozai mechanism vs nodal and apsidal precession)
<queqiao-> ⟨night_beast⟩ ⟪egg⟫ To put it another way, albeit with more […] ⮪ So my plane of reference is shifting? isn't that always the equator?
<paculino> The angle from your plane to the equatorial plane remains the same, but the angle from "up" on your plane to a reference meridian changes, as does the angle between the highest point on the orbit to an arbitrary (but consistent) "up" on your plane.
<queqiao-> ⟨egg⟩ ⟪night_beast⟫ So my plane of reference is shifting? […] ⮪ No, the equator, the grey plane in that figure, is not changing. The plane of your orbit, the yellow plane, is changing. But it is changing while the angle i remains constant.
<queqiao-> ⟨egg⟩ (That change is the change in Ω. The change in ω does not change the orbital plane.)
<queqiao-> ⟨night_beast⟩ So my orbital plane is orbiting? My AN/DN are orbiting?
<queqiao-> ⟨night_beast⟩ * orbiting on the plane of reference (the equator)?
<queqiao-> ⟨egg⟩ Orbiting is not the correct term for that, _precessing_ is, but other than that, yes. They are going around the equator at the rate given as _nodal precession_ in the analysis.
<queqiao-> ⟨egg⟩ The reason for that is that the Earth is oblate.
<queqiao-> ⟨night_beast⟩ So my nodal precession is -5.38 per day, so my longitude of my AN/DN is shifting 5.38 degrees per day?
<queqiao-> ⟨egg⟩ Yes.
<queqiao-> ⟨egg⟩ (Rule #3, no memes; but feel free to react with 🤯.)
<paculino> Would two images of a 3d model that crudely shows nodal vs apsidal precession be helpful?
<queqiao-> ⟨night_beast⟩ and this is a normal phenomenon for earth based sats because of the oblateness of earth's sphere? so in that case higher inclinations would exacerbate it right?
<queqiao-> ⟨night_beast⟩ not to mention this brings up a question about geosynchronous (not geostationary) orbits
<queqiao-> ⟨night_beast⟩ That to me is more confusing, but it might be how much you changed the orbit. that makes it look like it "flattened" out
<queqiao-> ⟨night_beast⟩ * orbit (and the frame of reference of the camera).
<paculino> The inclination and eccentricity remain the same, but the direction of each changes
<queqiao-> ⟨egg⟩ ⟪night_beast⟫ and this is a normal phenomenon for […] ⮪ The effect actually gets _smaller_ as the inclination gets higher, with no nodal precession for a perfectly polar orbit. The effect gets larger as the semimajor axis decreases though.