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…
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<queqiao->
⟨NathanKell (he/him)⟩ Hi friends! Does anyone have/know of a calculator for lunar frozen orbits? I'm trying to make a pair of highly-eccentric, polar-orbit lunar relays for farside ops but the moon is hungry! I feel like I've gotten somewhat close on one (I found an NTRS paper on frozen orbits that let me get somewhat close, but I'm still off enough...)
<queqiao->
⟨egg⟩ ⟪NathanKell (he/him)⟫ Hi friends! Does anyone have/know of a […] ⮪ No calculator, but there are pinned charts that should be usable; and then you can use the analyser to check your work.
<queqiao->
⟨Al₂Me₆⟩ ⟪egg⟫ No calculator, but there are pinned […] ⮪ Aren’t the charts for LLO though? He’s trying to do a fairly high orbit I think
<queqiao->
⟨NathanKell (he/him)⟩ Classic egg: ask for a calculator, get a scientific paper 🤣
<queqiao->
⟨NathanKell (he/him)⟩ ⟪egg⟫ No calculator, but there are pinned […] ⮪ I've been using the analyzer, yes, I got one stable (ish, with +/-600km drift in Ap/Pe over 90 days IIRC) but the one with the opposite ArgPe gets EATED after only like 30.
<queqiao->
⟨egg⟩ ⟪NathanKell (he/him)⟫ Classic egg: ask for a calculator, get […] ⮪ Looking at that paper though, I do not think such a calculator would be a simple thing. You can at least look at the examples therein though.
<queqiao->
⟨NathanKell (he/him)⟩ ⟪egg⟫ Looking at that paper though, I do not […] ⮪ I agree, you'd need to fix 3 of the 4 parameters.
<queqiao->
⟨NathanKell (he/him)⟩ ⟪egg⟫ Looking at that paper though, I do not […] ⮪ But assuming you did fix 3 of the 4, I don't see why the math wouldn't work?
<queqiao->
⟨egg⟩ … 4?
<queqiao->
⟨NathanKell (he/him)⟩ ecc, argpe, inclination, and sma, no?
<queqiao->
⟨egg⟩ The moon is not invariant by rotation. That is why it eats your satellites.
<queqiao->
⟨egg⟩ And the RGT solutions are discrete, so I don’t think you can fix anything.
<queqiao->
⟨egg⟩ See op. cit. pp 7 sq. for an outline of the method to find those.
<queqiao->
⟨egg⟩ * pp.
<queqiao->
⟨NathanKell (he/him)⟩ Well the pinned message I was pointed to only mentions 4 parameters.
<queqiao->
⟨egg⟩ Yes, but those are low orbits; there I think you can hope that the moon gets averaged out in rotation.
<queqiao->
⟨NathanKell (he/him)⟩ And this (that I was looking at the last two nights) seemed to imply there were calculations that could be done. https://ntrs.nasa.gov/citations/20080041459 but perhaps I missed a reference to low orbits there
<queqiao->
⟨NathanKell (he/him)⟩ See pp6-7
<queqiao->
⟨egg⟩ Slides tend to lack the context needed to properly understand the limitations without the actual presentation ; but see p. 17, 4th ☾.
<queqiao->
⟨NathanKell (he/him)⟩ So you are reading that as implying the entire paper only covers such orbits. Which given the rest of the context is I guess correct.
<queqiao->
⟨NathanKell (he/him)⟩ * presentation
<queqiao->
⟨egg⟩ Well, that too, but I was specifically noting the 4th ☾: Use of simple differential corrector
<queqiao->
minimal drift in e and ω. That does not sound like a straightforward calculator.
<queqiao->
⟨egg⟩ Well, that too, but I was specifically noting the 4th ☾: Use of simple differential corrector to vary initial conditions and target on minimal drift in e and ω. That does not sound like a straightforward calculator.
<queqiao->
⟨egg⟩ But yes, for low orbits with ω=±90°, you should be able to go with the pinned chart for the right a and just pick e(i) in those ranges where that e does not land you into the ground. I think high orbits are messier.
<queqiao->
⟨Al₂Me₆⟩ ⟪egg⟫ Well, that too, but I was specifically […] ⮪ ~Optimiser when~
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<queqiao->
⟨sierra_hotel⟩ Makes sense now why I couldn't find any info on how to get into a Lunar halo orbit around L2 😄
<queqiao->
⟨Al₂Me₆⟩ ⟪sierra_hotel⟫ Makes sense now why I couldn't find any […] ⮪ That’s a distinct issue. Here’s how: do a TLI as you normally would, such that you come around behind the Moon, roughly equatorial. Do a retrograde burn of ~150 m/s IIRC at periselene; this will swing you ‘forward’ with respect to the Moon, if you look in EML. With the right burn you’ll see your orbit wrap around L2 after the flyby. Fine tune from...
<queqiao->
... there; you only need fractions of a m/s.
<queqiao->
⟨Damien⟩ didn't someone on here get into one?
<queqiao->
⟨Damien⟩ I remember you discussing it with them egg
<queqiao->
⟨Damien⟩ or was that just a synchronous
<queqiao->
⟨Damien⟩ can't remember
<queqiao->
⟨egg⟩ sun-synch, not synch
<queqiao->
⟨StarcatcherKSP⟩ And a side note, is there any tidally-locked planets that has their synchronous orbit attitudes equal to their L-1 point
<queqiao->
⟨StarcatcherKSP⟩ * L-1/L2
<queqiao->
⟨egg⟩ Though sun-synchronism is also reported as impossible ibid, sub-table (d)
<queqiao->
⟨egg⟩ > 0 nodal revolutions O_o ⮪ yeah this is suspicious.
<queqiao->
⟨StarcatcherKSP⟩ ⟪egg⟫ It is indeed impossible, see […] ⮪ H - how in the world are you capable of sending these brainhurting science papers like it’s your ordinary math homework
<queqiao->
⟨egg⟩ My bio is not entirely inaccurate.
<queqiao->
⟨egg⟩ (Also on this one I have a physical copy within reach.)
<queqiao->
⟨StarcatcherKSP⟩ ⟪egg⟫ My bio is not entirely inaccurate. ⮪ I remembered asking you this one before but I don’t remember Principia being a playable game
<queqiao->
⟨StarcatcherKSP⟩ * still don’t recall
<queqiao->
⟨StarcatcherKSP⟩ And your bio is in Chinese and Akkadian
<queqiao->
⟨StarcatcherKSP⟩ I mean what is the purpose of writing your bio in cuneiform
<queqiao->
⟨StarcatcherKSP⟩ But then I wouldn’t be surprised if you actually did study the entire history of ancient Mesopotamia just to write that
<queqiao->
⟨Al₂Me₆⟩ Speaking of which. What’s the first line of your bio say? I assume the third line is the translation of ‘an egg drowning in a sea of papers’.
<queqiao->
⟨egg⟩ ⟪Al₂Me₆⟫ Speaking of which. What’s the first […] ⮪ They both say that, the first in Akkadian, the third in Sumerian.
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<queqiao->
⟨Al₂Me₆⟩ Of course.
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<raptop>
Starcatcher: fiddling with equations, I get a niave distance for a synchronous orbit for a tidally locked body scaling with (\frac{m}{M})^{1/3}, but it looks like L1 distance scales as (3 \frac{m}{M})^{1/3}
<raptop>
But, if you have lagrange points, do you really mind that the distance is different?
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<queqiao->
⟨bobkermanindustries.⟩ Is Principia more CPU or GPU heavy?
<queqiao->
⟨test_account9540⟩ Only CPU heavy, doesn't use GPU at all