Advanced Question Planetary Orbital Periods?

[Mr Martian]

Hi All,

I'm just wondering if anyone knows exactly how Orbiter calculates the orbital periods of planets and moons? I don't mean those with modules and ephemerides, just those with orbital elements defined in the .cfg file. The 'Info' tab in-game allows you to see the orbital period of celestial bodies in seconds, but only to 3 decimal places, I can't see any other way to see a more precise value. If I want to develop a tidally-locked moon, I will need to know the exact orbital period of the moon in seconds. I figure orbiter uses the standard formula to claculate orbital period (T = 2π√(a³/GM), but the displayed result for periods in-game differ from that which I calculate them to be.

Does Orbiter calculate the mass of the primary body (the sun, host planet etc) to be that which is defined for the body, or the sum of the host and all its satellites? Do we know the excat constants Orbiter uses gor the gavitational constant etc? If anyone knows exactly how Orbiter calculates this, I'd love to know!

Thanks in advance all!

 

[N_Molson]

Is this what you are looking for ?

 

[Mr Martian]

Thanks @N_Molson
I found this formula, what I was actually looking for was the constants that Orbiter uses for these calculations, specifically in this case the value for the gfravitational conmstant. I also wanted to know if Orbiter takes into consideration the combined mass of the parent object and its satellites for the mass of the 'primary', or just the mass of the parent object. In this case, I think the main confusion I had stemmed from the fact that Orbiter (at least in the 2024 manual) uses the below:

This differs from the contemporary CODATA recomended value of 6.67430 (see here). Any idea why Orbiter uses an older value for G?

Thanks!

 

[n72.75]

This differs from the contemporary CODATA recomended value of 6.67430 (see here). Any idea why Orbiter uses an older value for G?

This would be worth checking in the code.

Some things may not have changed much since circa 2000 in the code. Probably worth a full review and some tests.