What is a safe duna high orbit?

[KT]

I have a ship that just escaped Ike to get into a 3400km ca. orbit. What is the lowest possible safe duna orbit (higher than Ike orbit of course) where you can't encounter ike?

[maj.solo]

Unfortunately I have not seen if you can get the PE and AP for planets and moons in map view. There is a little grey icon on the right that looks like a planet where you get info about atmosphere and gravity etc.

So to ansver your question we need Ike-AP + Ike-SOI = Your-New-PE that you must not drop below in Your-Duna-Orbit.

Ike apoapsis = 3 296 000 m ( from Duna center )
Ike-SOI = 1 049 598.9 m ( from Ike center )
( source http://wiki.kerbalspaceprogram.com/wiki/Ike#cite_note-centered-1 )

So .... 3 296 000 + 1 049 599 = 4 345 599 m

Is this correct? Does it make sense?

[Joschi]

Edit 2:
'In orbital mechanics, the apsis technically refers to the distance measured between the centers of mass of the central and orbiting body. However, in the case of spacecraft, the family of terms are commonly used to refer to the orbital altitude of the spacecraft from the surface of the central body (assuming a constant, standard reference radius).'
(source: https://en.wikipedia.org/wiki/Apsis)

The same obviously applies to the periapsis as well then.

So this is where things get confusing - I would again argue that the Ike (planetary body) apoapsis is calculated from Dunas center of mass (as maj.solo pointed out), however the periapsis of your ship (spacecraft) is calculated from Dunas surface thus requiring you to subtract Dunas equatorial radius in order to 'convert' between both ways of calculating orbital altitudes.

Ike apoapsis = 3 296 000 m ( from Duna center )
Ike-SOI = 1 049 598.9 m ( from Ike center )
Duna equatorial radius = 320 000 m (also from KSP wiki)

3 296 000 + 1 049 599 - 320 000 = 4 025 599 m (spacecraft periapsis)

Thoughts / objections?

[Joschi]

Another possibility is to exactly match ikes orbit but e.g. on the opposite site of Duna. That way you can't get an encounter while being closer to Duna compared to a safe orbit above ike.

[maj.solo]

Originally posted by »BoH.Crew×IRA™:

Edit: nvm - Ike apoapsis should be calculated from Duna sealevel so there is no need to subtract Dunas equatorial radius...

Only reason for that is that the altimeter on the space craft is from surface. But if you take the numbers above and set the altimeter to that you DEFINITELY will NOT get into Ike SOI,

Measuring from the center makes it easier add and subtract distances in various directions. He could recalculate

Ike_AP + Ike_SOI - Duna_Equatorial_Radius

[Joschi]

Yes - I read a bit more and edited my post yet again - sorry for the confusion :-/

You definitely want to set the altimeter to something higher than the theoretical minimum but that is what was asked for here ;)

4 026 000 m should be safe enough though.

[KT]

ok guys i have figured it out by myself. since the ike AP ingame is listed from the surface of duna and the spacecraft AP and PE is too, we don't care about duna radius. it is about 3166 km from duna's surface to ike's center. ike SOI is listed in the wiki to be about 1050 km from the center of ike. so our PE is 3166+1050= 4216km at least.

[Limmin]

What's Duna's SOI radius? (You can orbit well out to 60,000 km or so, maybe even more, around Kerbin. So how far out can you orbit Duna?)