raptop changed the topic of #kspacademia to: https://gist.github.com/pdn4kd/164b9b85435d87afbec0c3a7e69d3e6d | Dogs are cats. Spiders are cat interferometers. | Космизм сегодня! | Document well, for tomorrow you may get mauled by a ネコバス. | <UmbralRaptor> egg|nomz|egg: generally if your eyes are dewing over, that's not the weather. | <ferram4> I shall beat my problems to death with an engineer. | We can haz pdf
<B787_300> I made this nice calculator for an undergrad class https://usercontent.irccloud-cdn.com/file/CB1eDu36/image.png
<B787_300> what is the inclination and Altitude?
<B787_300> and area and mass and c_d?
<B787_300> egg|laptop|egg: to give you an idea of what you need, over 1 year a 40 kg sat with a area od 3 m^2 in a 474 circular sun sync at 97.3 deg inc you need 34.57 m/s every year
<egg|laptop|egg> right, my question is more whether it's done as 95 mm/s every day if close recurrence is needed or whether that level of precision is infeasible
<B787_300> how good is the ground network supporting the satellite? IE how does the satellite know it is not in the right orbit
<B787_300> And what is the satellite doing... if it is doing electro optical imagery you might not want to be thrusting while the aperture is open.
<egg|laptop|egg> so right now I'm looking at 福爾摩沙衛星二號 (Formosat-2, formerly ROCSAT-2)
<B787_300> Similarly you will have to stop ops to orient the engines in the right way unless you are doing funky stuff with engine mountings
<B787_300> Oh and what is the minimum pulse on the engines?
<B787_300> Because that will effect how often you can do stationkeeping
<egg|laptop|egg> the altitude was about 890 km, the thing had a 1-day-recurrent sun-synch orbit passing over taiwan every day, and I have no idea what engines it had
<B787_300> egg|laptop|egg: I highly doubt they maneuvered once a day... maybe once every week or 2 because who really cares if you drift a couple minutes before or after the nominal design time?
<egg|laptop|egg> yeah I guess that makes sense
<B787_300> Plus that would probably put the required dv in a much easier to hit range for chemical thrusters
<egg|laptop|egg> for TOPEX/Poseidon it seems they keep the ground track to within < 1 km of nominal
<B787_300> Are those part of the A train?
<egg|laptop|egg> no, but it was in tandem with Jason-1 at some point
<egg|laptop|egg> (which was then itself in tandem with Jason-2, but by then TOPEX/Poseidon was decommissioned)
<egg|laptop|egg> it seems that over 1993-1999 TOPEX/Poseidon had just 13 OMMs?
<egg|laptop|egg> at 1 300 km alt.
<egg|laptop|egg> and apparently that was enough to keep it within 1 km of the nominal track
<egg|laptop|egg> "MANEUVER ERROR MODEL ΔV (Fixed) 0.013 mm/s."
<egg|laptop|egg> (that's for TOPEX/Poseidon)
<egg|laptop|egg> and the OMMs 2 through 9 are < 5 mm/s
<egg|laptop|egg> (from Bhat, Shapiro, Frauenholz, and Leavitt, TOPEX/Poseidon orbit maintenance for the first five years, AAS 98-379)
<egg|laptop|egg> (which I should print out and give to my cat probably)
<B787_300> egg|laptop|egg: yeah using my calculator with JASON-1 like specs (1325 km orbit @66 deg, 500 kg mass 8 m^2 area [estimated]) the required correction for one year is 0.03 m/s
<egg|laptop|egg> B787_300: what do you get on 890 km, 98°.77?
<B787_300> 0.06 m/s
<B787_300> (over i year)
<B787_300> s/i/1
<galois> B787_300 meant to say: (over 1 year)
<egg|laptop|egg> imaginary years!
<egg|laptop|egg> ... what is the pluralization of complex numbers, is it i year or i years
<egg|laptop|egg> cc bofh
<B787_300> now i will say because i havent alrready... this calculator is very simplistic and doesnt do things like seasonal or diurnal variations
<egg|laptop|egg> yeah but it sounds like a reasonable order of magnitude
<bofh> egg|laptop|egg: I assume i year, like all roots of unity are a singular quantity i believe.
<egg|laptop|egg> bofh: as you know, the plural case depends on more than the numeric value though,
<egg|laptop|egg> i should sleep
<egg|laptop|egg> also that file should be called analyser
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<bofh> same thing :P
<egg|cell|egg> Both: how are the comments
<bofh> egg|cell|egg: that's a fairly smol fudge factor, honestly.
<egg|cell|egg> I keep reading ixion as iximeow
<egg|cell|egg> Ιξιμήω
<bofh> rofl
<UmbralRaptop> 28978 iximeow
<iximeow> egg|cell|egg: it pings me every time too
<iximeow> proper highlights are for people with their lives together
<egg|cell|egg> Same with eggpuns or egg containing words
<egg|cell|egg> Wait I see stars?!
<egg|cell|egg> Ok but very cloudy still so zzz
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* UmbralRaptop recalls hitting 40-odd stalk words on irssi
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<egg|cell|egg> Bofh: have you seen the Paris Brest picture
<bofh> nope, but I assume it's like a typical Paris Brest
* bofh checks it out
<egg|cell|egg> Why am I not zzz
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<kmath> <Integrity_Guy> That feel when you’re watching the game with your homies and you all start instinctively purring and “kneading” the… https://t.co/AQvZwRnc0f
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* egg|laptop|egg meows at bofh, whitequark, et al.
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<egg|laptop|egg> "averaged mean inclination"
<whitequark> warning: word may contain egg
<egg|laptop|egg> hah
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* egg|laptop|egg stares at the Capderou book
<egg|laptop|egg> bofh: it writes Feng Yun-3 as 風雲三 rather than 风云三
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<oeuf> cc rqou
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<egg|laptop|egg> bofh: meow
<bofh> egg|laptop|egg: so it seems like just the traditional form of the name. not sure why but I don't think it's invalid?
<egg|laptop|egg> bofh: yes it's the traditional form
<egg|laptop|egg> bofh: it's a PRC sat :-p
* egg|laptop|egg pets cat
<egg|laptop|egg> bofh: how should I measure the inclination and eggscentricity
<bofh> measuring inclination should be easy, it's just the angle between orbital plane and ecliptic, so I think just an arctangent suffices?
<bofh> eggscentricity... no idée.
<egg|laptop|egg> bofh: an arctangent suffices to get the osculating eggscentricity
<egg|laptop|egg> s/egg.*/inclination/
<galois> egg|laptop|egg meant to say: bofh: an arctangent suffices to get the osculating inclination
<egg|laptop|egg> bofh: and it's easy to get the eggscentricity via the usual formulae
<egg|laptop|egg> bofh: my question is how do I define a meaningful mean inclination or mean eggscentricity (ideally one that's easy to compute from a cartesian trajectory)
<bofh> I don't think inclinations generally vary that much without explicit stationkeeping, so honestly just using the osculating is probably *sufficient*.
<bofh> Mean eggscentricity... I actually had to look this up, sec, I have two papers.
<egg|laptop|egg> bofh: angle of the trajectory with the equator? max latitude? average of the osculating inclinations over an orbit?
<bofh> average over an orbit should be more than fine
<egg|laptop|egg> bofh: i and e both have short-period variations
<egg|laptop|egg> the osculating elements do very much vary over one orbits
<egg|laptop|egg> "one orbits"
<egg|laptop|egg> i am good at plural
<bofh> one orbit(s)
<bofh> :p
<bofh> anyway 1 moment
<egg|laptop|egg> bofh: the problem with averaging the osculating value over an orbit is fig. 2 of https://elib.dlr.de/103814/1/Spiridonova_ISSFD_2014_upd.pdf
<egg|laptop|egg> the mean eggscentricity in both theories discussed is below all osculating eggscentricities
<bofh> Yep, this is very true for eggscentricities.
<bofh> Like, I'm trying to find the paper I read that actually does this sensibly.
<bofh> (it was awhile ago, like a year or so)
<egg|laptop|egg> bofh: is there some sensible discrete definition, e.g. from apsis radii?
<egg|laptop|egg> bofh: for the periods you have the anomalistic and draconitic periods as the periapsis-to-periapsis and ☊-to-☊ times, which is nice
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<egg|laptop|egg> bofh: meow
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* egg|laptop|egg stares at ixion
<oeuf> << <<<<<<< << <<< <<< <<
<oeuf> << << << << << << <<
<oeuf> << <<< << << << << << <<
<oeuf> << << << << << << <<
<oeuf> << <<<<<<< << <<< <<< << <<<
<egg|laptop|egg> That's one way to write ΙΞΙΩΝ, I guess
<egg|laptop|egg> iximeow: does ιξι ping you
<egg|laptop|egg> !u ≡
<galois> ≡: U+2261 IDENTICAL TO
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<bofh> egg: meow. sec.
<egg|laptop|egg> note to egg https://gcmd.gsfc.nasa.gov/KeywordSearch/Metadata.do?Portal=idn_ceos&KeywordPath=%5BPersonnel%3A+Last_Name%3D%27ADAMSON+(DECEASED)%27%2C+First_Name%3D%27HEATHER%27%5D&EntryId=POEs&MetadataView=Full&MetadataType=0&lbnode=mdlb1
<egg|laptop|egg> "CD-ROMs are being produced and are available as the data are processed" um
<egg|laptop|egg> okay so there are POEs for TOPEX/Poseidon, now how do i get them
<egg|laptop|egg> the IGS has things for GNSS sats http://www.igs.org/products
<egg|laptop|egg> Aha, SP3 files for Jason-1 on IGN FTP here ftp://doris.ign.fr/pub/doris/products/orbits/grg/ja1
<egg|laptop|egg> bofh: that Drake meme, with Two-line element set / Extended Standard Product 3 Orbit Format
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<egg|laptop|egg> this might be TOPEX/Poseidon? ftp://doris.ign.fr/pub/doris/products/orbits/lca/top/
<egg|laptop|egg> bofh: meow
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<iximeow> egg|laptop|egg: it appears not
<egg|laptop|egg> clearly you should fix that
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<_whitenotifier-7e6b> [Principia] ArXen42 starred Principia - https://git.io/fhHSI
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<egg|laptop|egg> bofh: B787_300: do you know where in the orbit the osculating inclination is maximal (resp. minimal)?
<B787_300> nope
<egg|laptop|egg> bofh: also you should tweet that golub & van loan selfie
* egg|laptop|egg pokes bofh with a flyswatter
* egg|laptop|egg scratches head
<egg|laptop|egg> ... oh, there's an easy way to compute the mean of the successive differences. derp.
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<egg|laptop|egg> otoh I'm computing the uncertainty too so that doesn't optimize itself quite as nicely
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<egg|laptop|egg> oh i should have ดาวเทียมไทยโชต as a test case
<egg|laptop|egg> bofh: meow
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<egg|laptop|egg> where is my phone
<egg|laptop|egg> egg|cell|egg
<egg|cell|egg> Meow
<_whitenotifier-7e6b> [Principia] CaptainBalls opened issue #2072: Parachutes cut at aproxx 8m above sea level - https://git.io/fhH9h
<_whitenotifier-7e6b> [Principia] eggrobin commented on issue #2072: Parachutes cut at aproxx 8m above sea level - https://git.io/fhHHU
<kmath> <AsteroidEnergy> MRO captures Insight and its two circular solar panels on the surface of Mars. The bright point of light is the SEI… https://t.co/jTag7TdoYj
<_whitenotifier-7e6b> [Principia] CaptainBalls edited issue #2072: Parachutes ineffective below 8m above sea level - https://git.io/fhH9h
<_whitenotifier-7e6b> [Principia] CaptainBalls edited issue #2072: Parachutes ineffective below 8m above sea level - https://git.io/fhH9h
<_whitenotifier-7e6b> [Principia] eggrobin commented on issue #2072: Parachutes ineffective below 8m above sea level - https://git.io/fhHHY
<_whitenotifier-7e6b> [Principia] eggrobin edited a comment on issue #2072: Parachutes ineffective below 8m above sea level - https://git.io/fhHHY
<_whitenotifier-7e6b> [Principia] CaptainBalls commented on issue #2072: Parachutes ineffective below 8m above sea level - https://git.io/fhHHs
<_whitenotifier-7e6b> [Principia] CaptainBalls edited a comment on issue #2072: Parachutes ineffective below 8m above sea level - https://git.io/fhHHs