00:57 <_whitenotifier> [Principia] Failure. #2148 failed - https://dev.azure.com/mockingbirdnest/445d7b9d-0318-42e3-857f-b69d40b1ed1b/_build/results?buildId=2148

07:45 <queqiao-_> ⟨Z​eusbeer⟩ Mars aerostationary is nuts

07:45 <queqiao-_> ⟨Z​eusbeer⟩ https://cdn.discordapp.com/attachments/480397772248580098/918045534827204609/unknown.png

07:45 <queqiao-_> ⟨Z​eusbeer⟩ it occilates between this arc over 5 years

08:37 <queqiao-_> ⟨e​gg⟩ that doesn’t sound too different from Earth then

08:37 <queqiao-_> ⟨e​gg⟩ you just have a stable longitude in the middle of that arc

08:40 <queqiao-_> ⟨e​gg⟩ (and the fact that this otherwise stays there for five years would tend to confirm that the babbling about phobos and deimos on Wikipedia is unwarranted; I would expect the Moon to be far nastier, because it’s off the equator)

08:44 <queqiao-_> ⟨e​gg⟩ Wikipedia does link to potentially interesting papers at least, both of which give you the stable longitudes

08:44 <queqiao-_> ⟨e​gg⟩ this Mars-Earth comparison is amusing https://ars.els-cdn.com/content/image/1-s2.0-S0032063313000044-gr3.jpg

08:45 <queqiao-_> ⟨e​gg⟩ Mars is far lumpier than the Earth

08:46 <queqiao-_> ⟨e​gg⟩ (from 10.1016/j.pss.2012.11.013)

08:54 <queqiao-_> ⟨!​Kerbinator (free to ping me)!⟩ hmm TWP actually takes eccentricity into consideration

08:54 <queqiao-_> ⟨!​Kerbinator (free to ping me)!⟩ hmm TWP actually takes eccentricity and inclination into consideration (edited)

08:55 <queqiao-_> ⟨!​Kerbinator (free to ping me)!⟩ and alexmoon.github.io also take this into account; only (very legacy) https://ksp.olex.biz/ don't take that into account

08:55 <queqiao-_> ⟨!​Kerbinator (free to ping me)!⟩ interesting

08:56 <queqiao-_> ⟨!​Kerbinator (free to ping me)!⟩ I think my trying to figure out how to calculate proper orbital elements of satelites under precession

08:57 <queqiao-_> ⟨!​Kerbinator (free to ping me)!⟩ I think my trying to figure out how to calculate proper orbital elements of **regular** satelites under precession (edited)

08:58 <queqiao-_> ⟨!​Kerbinator (free to ping me)!⟩ for inclination, LAN (relative to equator) precesses quickly, so I know the answer is roughly inpossible; I'll use an event to mark time (for example, landing time of Huygens probe, in JPL horizons)

08:58 <queqiao-_> ⟨!​Kerbinator (free to ping me)!⟩ however MNA is the problem

08:58 <queqiao-_> ⟨!​Kerbinator (free to ping me)!⟩ for inclination, LAN (relative to equator) precesses quickly, so I know the answer is roughly inpossible; I'll use an event to mark time (for example, landing time of Huygens probe, in JPL horizons, or Galileo reaching Jovian system) (edited)

08:58 <queqiao-_> ⟨v​on Kerman⟩ I misread the comment, thought it was about KAC launch window predictions. TWP should be correct, yes.

08:59 <queqiao-_> ⟨!​Kerbinator (free to ping me)!⟩ however MNA for JD2433282.5 is the problem, since ArgPe shaking heavily, and there are effects shown above. I want to get best precision in 120 years, so need to get the center of that arc (edited)

09:17 <queqiao-_> ⟨e​gg⟩ You should look at https://www.researchgate.net/publication/264860121_Mean_Element_Propagations_Using_Numerical_Averaging (which is roughly what Principia’s orbit analyser does).

09:17 <queqiao-_> ⟨e​gg⟩ I also found https://www.researchgate.net/publication/281638840_Precise_mean_orbital_elements_determination_for_LEO_monitoring_and_maintenance interesting.

09:18 <queqiao-_> ⟨!​Kerbinator (free to ping me)!⟩ thanks

09:18 <queqiao-_> ⟨!​Kerbinator (free to ping me)!⟩ Plain Excel averaging works very well for Sun (using body center for Jupiter and inside; using SSB for Saturn and outside)

09:19 <queqiao-_> ⟨!​Kerbinator (free to ping me)!⟩ but not for satelites

09:19 <queqiao-_> ⟨!​Kerbinator (free to ping me)!⟩ but not for satelites (needs to take a look) (edited)

09:21 <queqiao-_> ⟨!​Kerbinator (free to ping me)!⟩ but not for satelites (needs to take a look at better methods) (edited)

09:21 <queqiao-_> ⟨e​gg⟩ The important thing is averaging the right kind of elements. If you average usual Keplerian elements (eccentricity, argument of periapsis, etc.) you get utter garbage, in part because of the singularities. You want to use some sort of nonsingular elements (which is what both of the methods I linked do; Ely in particular uses the equinoctial elements, for those see https://ui.adsabs.harvard.edu/abs/197

09:43 <queqiao-_> ⟨e​gg⟩ The other important thing is choosing the period or periods over which to average; you want the notches of that filter where there are periodic phenomena you want to ignore (so obviously the orbital period itself to get mean elements, but you could also average over the periods of perturbators for long-term studies)

16:26 <queqiao-_> ⟨g​ravShark⟩ I'm a day late but thanks everyone for the responses to my question yesterday regarding interplanetary window planning

23:08 <queqiao-_> ⟨k​raimoco⟩ What's the difference between that and plain old geostationary?

23:10 <queqiao-_> ⟨🌈​Exilate⟩ geostationary for mars

23:10 <queqiao-_> ⟨🌈​Exilate⟩ that's what aerostationary is

23:11 <queqiao-_> ⟨Q​eDelphyn (Xšayāršā/-ām/-āyā)⟩ *areo-

23:13 <raptop> It's important to get your greek prefixes correct

23:18 <queqiao-_> ⟨🌈​Exilate⟩ autocorrect

23:19 <queqiao-_> ⟨K​obymaru⟩ Would a tethered balloon count as aerostationary orbit?

23:20 <queqiao-_> ⟨S​paceMarine⟩ tethered to what?

23:20 <queqiao-_> ⟨Q​eDelphyn (Xšayāršā/-ām/-āyā)⟩ the planet, obviously

23:20 <queqiao-_> ⟨S​paceMarine⟩ also if its in orbit its in a vacuum so

23:20 <queqiao-_> ⟨Q​eDelphyn (Xšayāršā/-ām/-āyā)⟩ and yes

23:20 <queqiao-_> ⟨S​paceMarine⟩ why would you need a balloon

23:21 <queqiao-_> ⟨Q​eDelphyn (Xšayāršā/-ām/-āyā)⟩ there is no such thing as a vacuum

23:21 <queqiao-_> ⟨S​paceMarine⟩ partial vacuum then

23:21 <queqiao-_> ⟨S​paceMarine⟩ still the point remains

23:27 <raptop> Putting a balloon on a tether so long you have dodge Phobos to prove a point

23:29 <queqiao-_> ⟨Q​eDelphyn (Xšayāršā/-ām/-āyā)⟩ no, we where talking about aerostationary, not areostationary.

23:32 <queqiao-_> ⟨e​gg⟩ clearly https://www.nasa.gov/directorates/spacetech/niac/2017_Phase_I_Phase_II/Evacuated_Airship_for_Mars_Missions/ is an areoaerostat

23:41 <raptop> the prolate spheroid has a point

23:44 <queqiao-_> ⟨Q​eDelphyn (Xšayāršā/-ām/-āyā)⟩ so, areoaerostats for Mars, HAVOC for Venus. Are there any more interplanetary airship missions we want to happen?

23:45 <raptop> might be able to do Titan

23:46 <raptop> The gas/ice giants hate you and want you to suffer

23:46 <queqiao-_> ⟨Q​eDelphyn (Xšayāršā/-ām/-āyā)⟩ high pressure ones for the gas giants perhaps?

23:46 <queqiao-_> ⟨🌈​Exilate⟩ titan helicopter

23:47 <raptop> nuclear powered helicopter

23:48 <queqiao-_> ⟨Q​eDelphyn (Xšayāršā/-ām/-āyā)⟩ 1.45 atm mainly N2 on Titan. sounds pretty comfy for an airship.

23:48 <queqiao-_> ⟨Q​eDelphyn (Xšayāršā/-ām/-āyā)⟩ just put SLAM on Titan

23:49 <queqiao-_> ⟨Q​eDelphyn (Xšayāršā/-ām/-āyā)⟩ https://en.wikipedia.org/wiki/Supersonic_Low_Altitude_Missile