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->
⟨sunnypunny⟩ principia is very approachable
<queqiao->
⟨sunnypunny⟩ for a keosynchronous orbit just do everything the same as stock, the only real difference is when you need to adjust the orbital period. basically, switch to the surface reference frame, lengthen the prediction and make adjustments until the flying spaghetti monster overlaps itself
<queqiao->
⟨𒀯 𒄷 𒄈𒀭𒁇⟩ IIRC, wikipedia does a good job of explaining them
<queqiao->
⟨Exend⟩ i have NO idea what a keosynchronous or geosynchronous orbit is
<queqiao->
⟨Exend⟩ i have NO idea how to do a keosynchronous or geosynchronous orbit (edited)
<raptop>
[whatever]synchronous orbits have periods the same as the sidereal period of the planet's rotation
<raptop>
In practice you tend to want stationary orbits, where you have 0 inclination and eccentricity
<raptop>
The geo in geosynchronous means earth, so you'll sometimes see things like aereosynchronous for mars, etc
<raptop>
a keosynchronous orbit has a period of (technically just under) 6 hours, geosynchronous 24 hours, etc
<raptop>
What semi-major axis is necessary for these can be found in the literature (KSP wiki, wikipedia, etc), as well as directly calculated via Kepler's 3rd law
<queqiao->
⟨(ᴇxᴘᴇʀɪᴍᴇɴᴛᴀʟshells)⟩ in other words, if you're using the ECEF (or KCKF, or whatever-centred-whatever-fixed) reference frame, the spacecraft's projection should mostly be a single point
<raptop>
yeah, the "stationary" in stationary orbits is because as seen from the planet's reference frame, the ship appears to be hovering
<queqiao->
⟨sunnypunny⟩ just try to make a circular orbit at around 2863km
<queqiao->
⟨Exend⟩ WHAT IS RAPTOP
<queqiao->
⟨Exend⟩ oh my god
<queqiao->
⟨Exend⟩ that'll be hard to get used to
<queqiao->
⟨Exend⟩ what's raptop (edited)
<queqiao->
⟨(ᴇxᴘᴇʀɪᴍᴇɴᴛᴀʟshells)⟩ sheesh, no need to accidentally press the capslock key
<queqiao->
⟨(ᴇxᴘᴇʀɪᴍᴇɴᴛᴀʟshells)⟩ meanwhile, raptop can enjoy confronting an existential crisis over who or what they actually are
<queqiao->
⟨Al2Me6⟩ Days since Turing test failure: 0
<_whitenotifier>
[Principia] eggrobin labeled issue #3041: Progress bar in the orbit analyser is broken - https://git.io/JczAJ
<_whitenotifier>
[Principia] eggrobin opened pull request #3043: Use floating-point numbers, not integers, for a progress indicator in [0, 1] - https://git.io/JcVze
<queqiao-_>
⟨egg⟩ @Butcher @Al2Me6 just opened PRs for both your bugs, hopefully that should be in Grossmann next week
<_whitenotifier>
[Principia] pleroy labeled pull request #3043: Use floating-point numbers, not integers, for a progress indicator in [0, 1] - https://git.io/JcVze
<_whitenotifier>
[Principia] pleroy labeled pull request #3046: Correct the title of [Wan43] - https://git.io/JcVAf
<_whitenotifier>
[Principia] eggrobin commented on pull request #3042: Make FitHermiteSpline interruptible - https://git.io/JcwBI
<_whitenotifier>
[Principia] eggrobin closed issue #3033: Game stutters when vessel change state from landed to in flight or vice versa - https://git.io/Jn0Wt
<_whitenotifier>
[Principia] eggrobin pushed 4 commits to master [+0/-0/±11] https://git.io/JcwBL
<_whitenotifier>
[Principia] eggrobin synchronize pull request #3043: Use floating-point numbers, not integers, for a progress indicator in [0, 1] - https://git.io/JcVze
<_whitenotifier>
[Principia] eggrobin commented on pull request #3043: Use floating-point numbers, not integers, for a progress indicator in [0, 1] - https://git.io/JcwE3
<queqiao->
⟨Mike⟩ @egg have you decided to better ignore my question regarding not saving state on scene changes or not seen it? 😀
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<queqiao->
⟨egg⟩ I’m mostly confused by it
<queqiao->
⟨egg⟩ what do you mean by an unreal save ? wouldn’t trying to detect that not run into the risk of getting into an incoherent state given KSP’s fondness for invariants ? how would that event be related ?
<queqiao->
⟨Mike⟩ i mean a save triggered by a scene switch in contrast to a save triggered by a user clicking save. I know handling those differently, if possible at all, is not the cleanest solution, but i wonder if it would be possible with that event, so that on the subsequent scene load you get passed a save without principia data but take that data from an in memory store or something like that.
<queqiao->
⟨egg⟩ but a save triggered by a scene switch is still a save, right?
<queqiao->
⟨Mike⟩ I guess so
<queqiao->
⟨egg⟩ as in, if the game subsequently crashes, that save still happened
<queqiao->
⟨egg⟩ so failing to save would yield an incoherent and irrecoverable state
<queqiao->
⟨Mike⟩ Yeah, you wouldn't be able to laod sucha save after a crashed game
<queqiao->
⟨egg⟩ destroying the user’s save if they change scene seems like a poor user experience
<queqiao->
⟨Mike⟩ Yeah, you wouldn't be able to load such a save after a crashed game (edited)
<queqiao->
⟨egg⟩ I practically never save, I always rely on scene-change=save
<queqiao->
⟨egg⟩ so that approach would nuke all my games
<queqiao->
⟨Mike⟩ Ah okay. Well to be honest i probably would just disable saving on scene changes altogether if i could, but i see your point.
<queqiao->
⟨egg⟩ I think we know where we want to go tbh
<queqiao->
⟨egg⟩ for now it seems that the things that are hard to store in computed form are also those that you can’t display
<queqiao->
⟨Mike⟩ Well, if implemented it could be made optional - but i know it's not the nicest of workarounds, fingers crossed you find a better solution. 🙂
<queqiao->
⟨egg⟩ so the solution would be to store them in uncomputed form (simply « three years of free fall from here » which is the most extreme compression), and to keep the last n kilobytes in computed form (which would cover the long-duration trajectories you want to look at, the Voyagers etc.)
<queqiao->
⟨egg⟩ it is important to keep the data in uncomputed form because we don’t want to lose data; maybe in the future we will provide a way to say « I want to look at what my trajectory was at launch »
<queqiao->
⟨egg⟩ it is important to keep the data in uncomputed form because we don’t want to lose data; maybe in the future we will provide a way to say « I want to look at what the trajectory of my LEO sat was at launch 10 years ago » (edited)
<queqiao->
⟨Al2Me6⟩ Possibly stupid question: how does this handle burns and especially RCS?
<queqiao->
⟨Mike⟩ Hm, yeah, sounds nice, i guess you usually care about a much greater time frame of a cheaply stored path of a deep space probe than of an odd leo sat
<queqiao->
⟨egg⟩ those have to be stored normally, but they can’t last very long, because you have to be actively playing with that vessel for them to occur
<queqiao->
⟨egg⟩ hours of real-time gameplay are trivially cheap to store, the problem is years of timewarp
<queqiao->
⟨egg⟩ (in low orbit; interplanetary trajectories are cheap)
* raptop
imagines principia outputting megabytes of FITS files
<queqiao->
⟨egg⟩ SP3 files would probably make more sense
<raptop>
Standard dialect: diverges from the specification in two ways
<queqiao->
⟨egg⟩ no the descriptions are above not below
<queqiao->
⟨egg⟩ note that the two ILRS products are differently nonconformant
<raptop>
ah
<queqiao->
⟨egg⟩ the Center for Orbit Determination in Europe (CODE) operated by Astronomical Institute of the University of Bern (AIUB) produces standard-compliant files
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<queqiao->
⟨Damien⟩ Absolute madman
<queqiao->
⟨Damien⟩ That's the kind of thing that someone who wakes up in the morning, drinks 3 cans of monster for breakfast, and jumps out of the window to start the day does
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<raptop>
drinking cans of monster instead of having breakfast sounds like something @local_catgirl would do
<queqiao->
⟨egg⟩ I made eggs benedict this morning, but I have french windows here so I guess I go out the window
<_whitenotifier>
[Principia] pleroy commented on pull request #3043: Use floating-point numbers, not integers, for a progress indicator in [0, 1] - https://git.io/Jcwxa
<_whitenotifier>
[Principia] eggrobin d8540f2 - Merge pull request #3043 from eggrobin/3041 Use floating-point numbers, not integers, for a progress indicator in [0, 1]
<_whitenotifier>
[Principia] eggrobin closed pull request #3043: Use floating-point numbers, not integers, for a progress indicator in [0, 1] - https://git.io/JcVze
<queqiao->
⟨DRVeyl⟩ "I don't think that word means what you think it means."
<queqiao->
⟨egg⟩ (you could consider the g₀ to be part of the Iₛₚ but that’s another discussion, easily sidestepped by calling it the exhaust velocity :-p)
<raptop>
Δv is change in velocity, which is as it sounds like how much the rocket's velocity changes after the burn. I_{sp} is the rocket's specific impulse -- really the exhaust velocity of the propellants in funny units. g_0 is an arbitrary constant.
<queqiao->
⟨Exend⟩ no
<queqiao->
⟨Exend⟩ i cant understand it
<raptop>
m is the final mass of the rocket, and m_0 is the initial
<queqiao->
⟨egg⟩ yeah the g₀ * Iₛₚ thing is an obnoxious distraction
<raptop>
Yeah, I wish stock KSP used V_e instead of I_{sp}
<queqiao->
⟨egg⟩ really this is change in velocity = exhaust velocity * log of the mass ratio
<queqiao->
⟨Exend⟩ I don't understand anything in that equation and it'll stay that way for a few years
<queqiao->
⟨Exend⟩ probably
<queqiao->
⟨Standecco⟩ I don't really get what's there to understand
<queqiao->
⟨Exend⟩ the math
<queqiao->
⟨Standecco⟩ that means absolutely nothing
<queqiao->
⟨egg⟩ I am not sure how loudly insisting that you don’t understand, without saying what it is you have issues with, is going to help you understand
<queqiao->
⟨Exend⟩ everything about it
<queqiao->
⟨Exend⟩ its an equation that involves complicated math
<queqiao->
⟨badgermasher⟩ Why are we still engaging with this person?
<queqiao->
⟨Exend⟩ i dont know that math
<queqiao->
⟨Exend⟩ i dont know how to do that math (edited)
<queqiao->
⟨Al2Me6⟩ (A word of advice -- if there's one thing you don't want to do in this channel it's to invoke 🥚⛈️.)
<queqiao->
⟨egg⟩ the masher of badger raises an interesting point, ineggshaustible though my patience may be
<queqiao->
⟨Exend⟩ this channel too complicated for me
<raptop>
Also, at the risk of being a bit rude: Don't claim you have a PhD in a subject that the prolate spheroid has an MSc in
<queqiao->
⟨egg⟩ perhaps you have heard the word « exponential », if not the word « logarithm »
<queqiao->
⟨Standecco⟩ if he's scared of a graph I doubt he's even heard the word function
<queqiao->
⟨Standecco⟩ if he's scared of a graph I doubt he's even heard the word "function" (edited)
<queqiao->
⟨Exend⟩ u need tohave a phd in mathematics (edited)
<queqiao->
⟨Exend⟩ no i have not
<queqiao->
⟨(ᴇxᴘᴇʀɪᴍᴇɴᴛᴀʟshells)⟩ uh oh
<queqiao->
⟨Exend⟩ i have in several coding languages
<queqiao->
⟨Exend⟩ not in math
<raptop>
hrm, apparently a reply got eaten
<queqiao->
⟨egg⟩ I think that post from the raptop is a misunderstanding due to the bridge not showing replies as such, please ignore
<queqiao->
⟨(ᴇxᴘᴇʀɪᴍᴇɴᴛᴀʟshells)⟩ they basically describe the same concept
<queqiao->
⟨egg⟩ (I should see if there is a newer version of the bridge bot that knows about replies…)
<queqiao->
⟨egg⟩ a function is a thing that takes a number, that gives you back another depending on the one it took, much like a function that takes a number and returns a number in (programming language of your choice)
<queqiao->
⟨(ᴇxᴘᴇʀɪᴍᴇɴᴛᴀʟshells)⟩ (not necessarily numbers, but that's beyond the scope of this conversation)
<queqiao->
⟨egg⟩ (yes, and really we mean pure functions on the programming side, etc., etc.)
<queqiao->
⟨egg⟩ but anyway, you have a function exponential(number) which returns a number
<queqiao->
⟨egg⟩ the result grows very fast as its argument grows
<queqiao->
⟨egg⟩ the technical term for that « fast » being « exponentially », a term that you will very likely have encountered in common parlance
<queqiao->
⟨egg⟩ the rocket equation can be rewritten as
<queqiao->
⟨egg⟩ exponential(change in velocity / exhaust velocity) = initial mass / final mass
<queqiao->
⟨egg⟩ which means that (all other things being equal), as the desired change in velocity grows, the required initial mass of the rocket grows *exponentially*
<queqiao->
⟨egg⟩ which is why rockets that need to throw even tiny things onto interplanetary trajectories are immense compared to the ones that would lob the same into low orbits
<queqiao->
⟨(ᴇxᴘᴇʀɪᴍᴇɴᴛᴀʟshells)⟩ see: Saturn V vs. Saturn 1B
<queqiao->
⟨(ᴇxᴘᴇʀɪᴍᴇɴᴛᴀʟshells)⟩ see: Saturn V vs. Saturn IB (edited)
<raptop>
contrast the somewhat large rovers of Curiosity/Percy (launched by Atlas V 541s) vs the rather smaller New Horizons (launched by an Atlas V 551)
<queqiao->
⟨Standecco⟩ egg's patience really is limitless
<raptop>
Or more generally, how payloads to GEO are what, 1/3 that of to LEO?
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<queqiao->
⟨vevladdd⟩ This is the only way to access internet on my vessel. We are very far from shore now lol