Set Kerbin as target?

[THX1138]

Am I supposed to be able to set Kerbin as target (because I can't...)? Right click on it does nothing except give me the option to set some debris as target (which doesn't interest me).

Edited February 4, 2015 by THX1138

[*Aqua*]

You can't set a celestial as a target when you are orbiting it. You must be outside of it's sphere of influence to be able to do that.

[AlexinTokyo]

To be more specific, you can't target the body you're orbiting, or its parent (or grandparent, etc). So you can't target Kerbin while in the Mun's SoI either. Nor can you target the sun while orbiting Kerbin.

You can target other children of the same parent, so you could target Kerbin while orbiting the sun, or any of the other planets or their moons, and you can target Minmus while orbiting the Mun (or vice versa).

[THX1138]

I see. Thanks. Does it not make sense to set Kerbin as a target when you're orbiting the Mun? I was trying to optimise my return and a forum post was talking about the pink marker.

[*Aqua*]

Does it not make sense to set Kerbin as a target when you're orbiting the Mun?

Actually it makes no sense. No matter in which direction you burn you'll enter Kerbin's SOI (or crash into the Mun). So there's no way to determine a target because there are literally an infinite amount of them.

You could send a small satellite in low Kerbin orbit and target that instead.

[Sigma88]

iirc the best point to do a burn for a kerbin return should be 90° before you are exactly between kerbin and the moon (if you are orbiting the mun in the same direction the mun orbits kerbin, which most likely you are I guess), that way you will exit mun SOI going "Backwards"

I could be wrong

Edited February 4, 2015 by Sigma88

[WuphonsReach]

Alternately, keep a satellite in LKO (200km or so altitude) and use that as the target for setting up Hohmann transfers using MechJeb.

[Alshain]

iirc the best point to do a burn for a kerbin return should be 90° before you are exactly between kerbin and the moon (if you are orbiting the mun in the same direction the mun orbits kerbin, which most likely you are I guess), that way you will exit mun SOI going "Backwards"

I could be wrong

Your close, but the 90 degrees before is incorrect. You want to burn prograde when you are directly between the Mun and Kerbin when traveling in a 0 degree inclination orbit (or close to it). If traveling in a 180 degree inclination orbit, you want to burn prograde at the furthest point from Kerbin instead.

[Pecan]

Alternately, keep a satellite in LKO (200km or so altitude) and use that as the target for setting up Hohmann transfers using MechJeb.

If you're using MJ, just use the "return from a moon" option ^^.

[Sirrobert]

I see. Thanks. Does it not make sense to set Kerbin as a target when you're orbiting the Mun? I was trying to optimise my return and a forum post was talking about the pink marker.

Not really. Just make sure you exit the Mun's SOI in the direction of the Mun's retrograde marker, and you have a perfect return.

So burn prograde rhoughly when you are between the Mun and Kerbin

[Foxster]

Lots of good opinions here. But its still wrong. You should be able to click on Kerbin and get the option to set it as the target (or focus) .

[klesh]

If you're using MJ, just use the "return from a moon" option.

I think is weird people would use a button like that. Isn't actually flying your spaceship fun?

[Sirrobert]

Lots of good opinions here. But its still wrong. You should be able to click on Kerbin and get the option to set it as the target (or focus) .

Why? What would it accomplish? There's NOTHING you gain by targetting a target body. Except 'you can do it', which isn't worth the coding time.

You can already set it as focus, by doubleclicking (just like every other thing)

I think is weird people would use a button like that. Isn't actually flying your spaceship fun?

Yes, it's extremely fun to do the same extremely easy manouver I've done 1000 times already again. Really puts the mind at work

[Nemrav]

The reason I wish I could target Kerbin is to get a flat inclination relative to it (to make station building easier)...

[Sirrobert]

You won't get that by targetting the parent body, since inclination information is based on comparing the orbits. And you can't compare orbits with a parent body

We need a seperate tool for that (I agree we need that though).

[thadisjones]

The reason I wish I could target Kerbin is to get a flat inclination relative to it (to make station building easier)...

Target the Mun, and make all the permanent orbits you want on the same plane as the Mun, and that will be just as good?

[ajburges]

The reason I wish I could target Kerbin is to get a flat inclination relative to it (to make station building easier)...

May I recommend Kerbal Engineer as a mod. It will give you inclination and time to nodes (with hundreds of other configurable readouts)

That (and Kerbal alarm) finally got me to install mods and I can't dream of returning to stock game (still won't run moded parts or simulation though).

[Mahnarch]

I seem to find burning prograde at 2 O'clock [w/Kerbin at your 12] works best for me.

Usually a quick 30-40 sec burn will plop me at about 45k meters in the Kerbosphere*.

*Did I just make that word up?! I just thought of it, but maybe I read it here and buried it.

Patent pending, if so!

[Alizerin]

Why? What would it accomplish? There's NOTHING you gain by targetting a target body. Except 'you can do it', which isn't worth the coding time.

You can already set it as focus, by doubleclicking (just like every other thing)

To be fair, there have been times when I have wanted to select Kerbin (or the Sun) as a target, and simply couldn't do it because of this weird behavior. It's always been frustrating and it has always seemed (to me) to be a potentially useful tool.

I think either all bodies should have the same behavior (ie: the user can target all bodies the same regardless of where they are) or the game should give useful information when it refuses to do so. Something as easy as a note which says "cannot target the parent body of a system," with a sad sounding beep would probably suffice.

While they're at it: having the Kerbal space port viewable as an icon that you can target would be great, too. "Space ports" could be a new tab in the map view/tracking station, with the ability to right click on them, switch-to, and set intercepts.

[Fisk02]

Thats making making sense if you ask me...

[Pecan]

I think is weird people would use a button like that [MJ: return from moon]. Isn't actually flying your spaceship fun?

1. What Sirrobert said

2. MJ only calculates the manoeuvre node for you, if you ask it to

3. Real planes and spacecraft have autopilots

4. People aren't having fun the wrong way

[klesh]

1. What Sirrobert said

2. MJ only calculates the manoeuvre node for you, if you ask it to

3. Real planes and spacecraft have autopilots

4. People aren't having fun the wrong way

I said its weird, I said nothing about the wrong way. Don't bunch me in with the haters, m'kay?

[wibou]

I wish we could have ONE thread that doesn't end with a flamewar PRO-MechJeb VS CON-MechJeb...

It's a mod for god's sake!

You need to MANUALLY install it. If you did install it, I'm assuming you still have fun playing the game that (totally different and probably easier) way, otherwise you wouldn't have installed it, right?

New players learning only with MechJeb may find it difficult to do it manually then, but that's quite another debate, isn't it?

[Recon777]

I may not have spotted it but what actually IS the solution then if you want to match inclination with your parent body's orbit (not its rotation)? I tried doing exactly what the OP was talking about here last night. Was orbiting the Mun and wanted to line up with the Mun's orbit around Kerbin. MJ gives you "equatorial inclination" but what if the parent body itself is inclined relative to its orbit? Like in the case of Earth, if you wanted to shoot off in the same plane as Earth's orbit around the sun, you'd have to line up with that orbit and NOT its equatorial rotation. How is this done other than by using the Mk1 Eyeball?

[Snark]

iirc the best point to do a burn for a kerbin return should be 90° before you are exactly between kerbin and the moon (if you are orbiting the mun in the same direction the mun orbits kerbin, which most likely you are I guess), that way you will exit mun SOI going "Backwards"

Your close, but the 90 degrees before is incorrect. You want to burn prograde when you are directly between the Mun and Kerbin when traveling in a 0 degree inclination orbit (or close to it). If traveling in a 180 degree inclination orbit, you want to burn prograde at the furthest point from Kerbin instead.

Pretty close, but actually, the optimal point will be somewhere between these two, depending on how much burn you're doing.

The ideal case (in terms of minimal dV expenditure) is for you to be traveling perfectly Kerbin-retrograde (relative to the Mun) at the point where you exit the Mun's SoI. Alshain's recommendation will start you heading in the right direction, but since the Mun's gravity will bend your trajectory a bit, you actually want to start your burn a few degrees earlier than that. (90 degrees is way too far-- Alshain's recommendation is closer than Sigma88's.)