OHM SPICE

[OrbitHangar]

Orbiter SPICE addon v0.1 (for testing only) (API v.060425) Using SPICE kernels (a type of NASA trajectory information file) this addon provides more accurate states of planets/satelites/etc... Some useful links: About NAIF: http://naif.jpl.nasa.gov/naif/about.html About SPICE: http://naif.jpl.nasa.gov/naif/aboutspice.html SPICE kernels for satellites: ftp://naif.jpl.nasa.gov/pub/naif/generic_kernels/spk/satellites/ Kernels for planets: ftp://naif.jpl.nasa.gov/pub/naif/generic_kernels/spk/planets/ --- Best regards, Alex Frost [email protected]

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[FlyingSinger]

This looks pretty interesting since it would seem to provide access within Orbiter to the most up to date JPL data for the planets and moons, along with a new Orbiter module that can propagate the state vectors for those objects (at least the ones for which you provide new cfg files) as Orbiter runs.

I haven't tried anything yet, but I have a couple of questions. Your sample cfg files reference several .bsp files which are available through JPL's ftp site. Presumably you have incorporated these data into your spice.dll since there are no .bsp or other data files in the zip file. Is that right? Or does the .dll somehow access data over the web? If not, then how would updates be handled? The .bsp data are valid over certain ranges of time which depend on the body. I assume planetary data can be valid for a pretty long time, while spacecraft could vary a lot (especially those which are still being maneuvered like Cassini).

I just read through the SPICE overview presentation and that toolkit provides an amazing range of capabilities, many of which are handled by Orbiter itself now but some of which could presumably be replaced by SPICE routines in some situations. I suppose that's your purpose in introducing a test version of a SPICE based planetary module along with sample cfg files for a few bodies. Sort of a proof of concept. Is that right?

I don't know how accurate the propagation codes are that Martin uses by default within Orbiter, and for educational and play purposes, I'm sure they are quite sufficient. People are probably not using Orbiter for actual mission planning, but with access to JPL data within Orbiter itself, following along with actual missions might be easier and more accurate.

Thanks!

 

[Ajaja]

If not, then how would updates be handled?

Kernel files must be downloaded from ftp manualy. You can create your own kernels using spkmerge.exe utility from http://naif.jpl.nasa.gov/naif/toolkit_C_PC_Windows_VisualC_32bit.html
For asteroids You can get SPK-kernels using telnet interface of HORIZONS system: http://ssd.jpl.nasa.gov/?horizons_doc#spk

I suppose that's your purpose in introducing a test version of a SPICE based planetary module along with sample cfg files for a few bodies. Sort of a proof of concept. Is that right?

To be honest, I had taken this idea from Celestia project http://www.shatters.net/forum/viewtopic.php?f=10&t=10112
I think it might be very useful in Orbiter too. Now, for testing purpose, I trying to add honest Pluto/Charon system into Orbiter, using SPICE-module with NASA ephemerides PLU017: http://www.orbiter-forum.com/showthread.php?t=1387

I don't know how accurate the propagation codes are that Martin uses by default within Orbiter, and for educational and play purposes, I'm sure they are quite sufficient.

It very accurate too, but only for planets (without Pluto unfortunately) and some moons (with *.dll modules).