Lunar Axis Precession not modelled in Orbiter?

[BrianJ]

Hi,
just been playing around with LRO trajectories in Orbiter (060929 version)and noticed that the precession of the Lunar Axis doesn't seem to happen in Orbiter.

This can be verified if you use the Visual Helpers/Planetarium Mode in Orbiter and enable "Target Equator" , "Ecliptic Grid", "Celestial Grid" etc.
and set the Moon as visual target. The LAN of the Moon's equator (green line) does not change with time.

My (limited) understanding is that it precesses with the same 18.6 year cycle as the Moon's orbit w.r.t. the ecliptic, but exactly out of phase.

A method for calculating the Right Ascension of the Lunar Pole is available in this document
http://ssd.jpl.nasa.gov/?lunar_doc

If this is so, perhaps it could be fixed in the next Orbiter version?

Regards,
Brian

EDIT: Duh! Of course, the Equatorial LAN is set by the Moon.cfg - so it's fixed. A cursory glance at the Orbiter API Reference .pdf doesn't reveal any way I can see of setting the Equatorial LAN from a .dll (although I'm not at all familiar with that part of the API). So, I guess it would be down to Dr.S. to fix, if he felt like it.

Cheers.

 

[tblaxland]

See this post from m6, in particular Chode's comments. AFAIK, there is no way to adjust a planet/moon's LAN through the API. Your best bet (and the approach taken by the NASSP crew, IIRC) is to include a custom moon.cfg.

 

[BrianJ]

See this post from m6, in particular Chode's comments. AFAIK, there is no way to adjust a planet/moon's LAN through the API. Your best bet (and the approach taken by the NASSP crew, IIRC) is to include a custom moon.cfg.

Ah, yes. Thanks.