Celestia Forums

I announce the release of my NAIF SPICE Kernel Solar System addon. This add-on makes use of Celestia's support for NAIF SPICE kernels to improve the accuracy of planetary and satellite positions. This add-on includes every planet, moon, and the Pluto system. Currently these SPICE kernels generally run from 1900-2053 with keplerian orbits or Celestia's built-in calculations used outside that timeframe. Accuracy runs from sub-km scales for the moon, ~1 km for Earth, Mars, and Venus, and 2-3 km for Mercury, Jupiter, and Saturn. Please read the instructions in the files linked below thoroughly before running. Most of the spice files are not included in order to reduce the file size of the add-on package. The file FILES TO DOWNLOAD.txt includes a list of all the files you need to download to the add-on's data directory. Grand total, expect to download 2-3 GB worth of files from the NAIF FTP site.

For now, I have created an add-on for the entire solar system, which includes a separate folder for Barycenters, which facilitates the use of Spice kernels in other add-ons, for other spacecraft. I have also created a separate add-on for the Cassini Mission, but that requires the Solar System Add-on for it to be used to full effect.

Solar System using NAIF SPICE kernels
http://pirlwww.lpl.arizona.edu/~perry/C ... mSPICE.zip

Cassini SPICE add-on
http://pirlwww.lpl.arizona.edu/~perry/C ... iSPICE.zip

Positions for Cassini run from Launch through the end of the Extended mission. However, the kernels for orientation run out on August 25, 2009.

This add-on requires Celestia Version 1.6, currently in development, but nearing completion. Compiled versions can be downloaded from the Development sub-forum.

Future SPICE add-ons include support for the following missions: Juno, New Horizons, Galileo, and Mars Reconnaissance Orbiter.

This screenshot shows one of the neat things that this add-on can display that the default orbit definitions can't. This shows the orbits of all the minor outer satellites of Jupiter. Each color corresponds to a different dynamical group of outer satellites. One thing you might notice are the kinks in the orbital paths. Particularly look at 2003 J2 near the lower left corner for an extreme example. These kinks are caused by solar perturbations on the orbit of these small rocks, where the sun's gravitational influence is almost as much as Jupiter's. So their orbits precess about Jupiter at a rather rapid rate. This shows up here as visible differences in the position of these moons between the start of an orbit and the end of the at orbit.

volcanopele wrote:

Jupiter_moons.jpg

This screenshot shows one of the neat things that this add-on can display that the default orbit definitions can't. This shows the orbits of all the minor outer satellites of Jupiter. Each color corresponds to a different dynamical group of outer satellites. One thing you might notice are the kinks in the orbital paths. Particularly look at 2003 J2 near the lower left corner for an extreme example. These kinks are caused by solar perturbations on the orbit of these small rocks, where the sun's gravitational influence is almost as much as Jupiter's. So their orbits precess about Jupiter at a rather rapid rate. This shows up here as visible differences in the position of these moons between the start of an orbit and the end of the at orbit.

Interesting...
Now, imagine we could have an automated fully transparent process that would update the Celestia default database according to Spice kernels to keep ALL bodies as accurate as possible... that would be fantastic...
As a parenthesis, concerning the kinks in the orbit we definitively need a better graphic solution but I guess Chris have this in his todo list for next big revision...

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Okay, if you already have the Saturn add-on, this does supercede that. If you downloaded the last version of my Saturn add-on, just move the .bsp files that start with "sat", like sat296.bsp, to the extras/zzSolarSystemSpice/data directory (that way you don't need to download them again). For the Cassini mission optional add-on linked above, move all the other .bsp and .bc files over to the extras/CassiniSPICE/data directory. You will need to download the following kernel that I added in the last few days:

ftp://naif.jpl.nasa.gov/pub/naif/CASSIN ... h_psiv2.bc

Once those kernel files are copied over, you should then delete the Saturn add-on so it doesn't interfere.

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Volcanopele, Sorry to trouble you after your extensive work on the SPICE kernel. But I just recently got interested to this subject. One point: how can one download easily (automatically) the numerous ftp files of the SPICE kernel I am not a specialist of DOS ! I probably need a simple batch. Sorry t ask so basic question
Michel

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Hi guys,

To date, for my usual purposes, I've been satisfied with the overall accuracy of the standard Celestia distribution, so I've never done anything with SPICE Kernels. Now, with New Horizons approaching it's goal in a few years time, I thought it's time I gave my Solar System an upgrade.

I apologize in advance if some of my questions are a bit ignorant, but I've never touched anything to do with SPICE files, so I'm a complete rookie with how it all hangs together.

So I have DL'd and installed volcanopele's solarsystem addon, and am in the process of downloading the latest kernels.
What's a little confusing is: when browsing the FTP site, how do you know which are the necessary or correct files to download?
The current list of available files is different to the list in JVV's last update (Mon Jan 30, 2012 6:14 am). Some listed by John are no longer there, there are some new ones with higher numbers. What is the rule?
So far I have got:
What's confusing is that in some cases, the higher numbered .bsp file seems to supersede the lower one (eg. There's a couple of .txt files: mar097-vs-mar085_deimos.txt and mar097-vs-mar085_phobos.txt which seem to suggest that mar097.bsp replaces mar085.bsp, plus the fact that mar085.bsp is no longer on the site would seem to suggest that this is the case.)
In other cases, it seems that all of them are required. eg. JVV uses al 3 of:

So, what's the process for determining which files to download? Is there even a general rule?
I would like to try and avoid downloading superseded files as some of them are quite large, but it seems that there is no clear rule that a higher numbered one supersedes the lower one. In some cases, all appear to be required.

Also, why does de423.bsp have to be installed in BOTH the aaBarycenters\data folder AND the zzSolarSystem\data folder? .. and are older versions de431.bsp?, de421.bsp?, no longer required, or is this a case where BOTH are still required?

Final question...
Aside from de423.bsp, which John mentioned above, how do we know if any of the original files that shipped with the addon:

cpck02Feb2009.tpc de421.bsp sat291.bsp
cpck_rock_02Feb2009_merged.tpc jup230-rocks.bsp ura074.bsp
cpck_rock_11Mar2009_merged.tpc jup255.bsp ura086.bsp
cpck_rock_11May2009_merged.tpc pck00008.tpc
and in
aaBarycenters/data
de421.bsp

need to be updated, deleted, or superseded?

EDIT:One final, final question:
It looks as though I need to get the SPICE Toolkit as well? ... or is this only required by the DEV's?
It seems to me that just some or all of the Utilities will be sufficient for my purposes: http://naif.jpl.nasa.gov/naif/utilities_PC_Windows_32bit.html

Cheers
CC

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I was just wondering if anyone has asked Chris how/if he plans to handle the issue of orbit display for planets with SPICED orbits.
For example, the orbit of a SPICED Earth looks like this:EDIT:[This is fine of course]...because Earth is now orbiting it's Earth-Moon barycenter, rather than the Sun...

BUT: Now it's the barycenter "Earth_bary" that is in orbit around the Sun). so an orrery of a (partially) SPICED Solar System will look rather bare of orbits (with orbit rendering enabled):

Perhaps all that is needed is the ability to render barycenter orbits, but I suspect it may be a bit more complicated than that.
Also, I suspect that SPICE kernels will play havoc with any scripts that rely on the usual parent-child relationships, ...although I haven't investigated this aspect yet.
eg.

There's also the issue of whether there is (any need for) an established convention for the naming of barycenters.
eg. Celestia's convention (pre-SPICE) was/is : "Pluto-Charon", whereas the implementations (by volcanopele) I've seen so far use "Pluto_bary", etc...

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John,

I don't understand what you mean. The aaBarycenters.ssc that I have appears to specify all Periods in "days". Are you saying that Periods should be in years?

It seems to me that it shouldn't be necessary to specify a Period at all for a SPICE orbit, as all the information for the orbit is contained in the KERNEL.

Interestingly, the planets which DO display orbits correctly on my system (eg. Jupiter) don't have any Period specified at all in the SSC.
[CORRECTION: The only planet that displays an orbit in the orrery is Saturn (which has: Period 10833 )

I'm going to go ahead and comment out all "Period" directives in aaBarycenters.ssc as I believe that will fix it.
EDIT: This made no difference.

I can't see what connection the Period could possibly have with the display of the orbits.

Perhaps this is actually due to having an incomplete set of kernels or referring to the wrong kernel. ??

CC

Chuft-Captain wrote:I can't see what connection the Period could possibly have with the display of the orbits.

Perhaps this is actually due to having an incomplete set of kernels or referring to the wrong kernel. ??

CC

Try add



in ReferencePoint to all planets and Period in years.

I have that in aabarycenters.ssc



If you have added ReferencePoints in other ssc files then add
Class "planet"
Visible true
Clickable true

too.

And don't add (") in true only "planet" must have (").

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Hi I have strange problem with shadows in Mars surface when I use SPICE

See this in animation of rotating Mars

https://www.youtube.com/watch?v=XhErXlMskJU


I have got all Barycenters and Solar system bodies here is my folder structure and ssc files:



00Barycenter.ssc



and 01SolarSystem.ssc

Hi Limax7... Where can I download .BSP files.... for Planets and major moons? I am interested in this kind of orbits... it's better for spacecrafts with.XYZV trajectories ... I am planning and building .XYZV trajectory now for spacecraft ( I will cal it Celestia-1) which will journey to Jupiter system... It will make several Callisto, Ganymede, Europa, Io flybys and enter in orbit around Ganymede...