Unfortuantly, most of the released SPKs for satellite orbits cover considerably less time than the original models, so next up is to extract the missing time periods from Horizons, and then see just what I can do to shrink this is a more manageable size. Most of the satellite orbits contain velocity data that Celestia shouldn't need, so it should be possible to shrink it by quite a bit.
One thing I've found surprising, though, is just how well Celestia's spice inplementation handles this massive dataset. On my little 1.3Ghz laptop (with only 128MB ram), Celestia draws both the standard and spice orbits with no noticable difference in responsiveness or framerates
What's the point? Well, Pluto is currently in the wrong place by about 1.5 million kilometers, for one thing. Also, it's kinda neat to actually watch Janus and Epimetheus switch orbits.
Anyways, here a couple of pics showing the difference. The untextured planets and moons are from the newer ephemeris.
What I was hoping for a bit of feedback on was what kind of timespan and filesize would people consider worth downloading? I know this is /way/ too huge to ever go into the mainstream distribution. Here is what is currently included..
Code: Select all
1 MERCURY BARYCENTER 1599 DEC 09 00:00:00.000 2201 FEB 20 00:00:00.000
2 VENUS BARYCENTER Same coverage as previous object
3 EARTH BARYCENTER Same coverage as previous object
4 MARS BARYCENTER Same coverage as previous object
5 JUPITER BARYCENTER Same coverage as previous object
6 SATURN BARYCENTER Same coverage as previous object
7 URANUS BARYCENTER Same coverage as previous object
8 NEPTUNE BARYCENTER Same coverage as previous object
9 PLUTO BARYCENTER Same coverage as previous object
10 SUN Same coverage as previous object
199 MERCURY Same coverage as previous object
299 VENUS Same coverage as previous object
301 MOON Same coverage as previous object
399 EARTH Same coverage as previous object
401 PHOBOS 1962 DEC 03 00:00:41.183 2024 DEC 30 00:01:05.183
402 DEIMOS Same coverage as previous object
499 MARS 1599 DEC 09 00:00:00.000 2201 FEB 20 00:00:00.000
501 IO 1924 DEC 29 00:00:00.000 2050 JAN 01 00:00:00.000
502 EUROPA Same coverage as previous object
503 GANYMEDE Same coverage as previous object
504 CALLISTO Same coverage as previous object
505 AMALTHEA Same coverage as previous object
599 JUPITER 1924 DEC 29 00:00:00.000 2050 JAN 01 00:01:05.183
601 MIMAS 1970 JAN 01 00:00:41.183 2050 JAN 01 00:01:05.183
602 ENCELADUS Same coverage as previous object
603 TETHYS Same coverage as previous object
604 DIONE Same coverage as previous object
605 RHEA Same coverage as previous object
606 TITAN Same coverage as previous object
607 HYPERION Same coverage as previous object
608 IAPETUS Same coverage as previous object
609 PHOEBE Same coverage as previous object
610 JANUS 1980 JAN 21 00:00:51.184 2014 DEC 28 00:01:05.183
611 EPIMETHEUS Same coverage as previous object
616 PROMETHEUS Same coverage as previous object
617 PANDORA Same coverage as previous object
699 SATURN 1970 JAN 01 00:00:41.183 2050 JAN 01 00:01:05.183
701 ARIEL 1980 JAN 02 00:00:51.183 2025 JAN 04 00:01:04.184
702 UMBRIEL Same coverage as previous object
703 TITANIA Same coverage as previous object
704 OBERON Same coverage as previous object
705 MIRANDA Same coverage as previous object
799 URANUS Same coverage as previous object
801 TRITON 1980 JAN 01 00:00:00.000 2048 DEC 30 00:00:00.000
802 NEREID Same coverage as previous object
807 LARISSA 1989 JUN 07 00:00:56.184 2024 JAN 01 00:01:05.183
808 PROTEUS Same coverage as previous object
899 NEPTUNE 1980 JAN 01 00:00:00.000 2048 DEC 30 00:00:00.000
901 CHARON 1965 JAN 01 00:00:41.183 2050 JAN 04 00:01:04.184
999 PLUTO Same coverage as previous object
It doesn't show up in this listing, but during the period listed for Phobos and Deimos the Mars ephemeris includes the planet's offset from the barycenter, while at other times Mars uses the barycenter's orbit.
BTW, I'm using 'modify' to do this, so any other addons will continue to work, and everything will revert to the normal Celestia orbit at times not covered by the ephemeris. I'm probably going to aim at getting about 1950-2050 in the final product, unless there's a reason to extend it further. That'll cover the space age, at least, with orbits that match what Horizons produces for spacecraft with a nice margin.