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Currently I've got a communications satellite in almost geosynchronous orbit around Kerbin. Unfortunately, it is not where I want it (I'd like it to be over the space center) and the orbit is off by enough that eventually it'll make a difference. I figure at this point I am as close as I'm ever going to be and I'd rather just cheat a little and edit the save files. Unfortunately, I don't know quite what I'm doing and I don't want to mess up. Can anyone help me understand what I need to edit and do?

This is what I currently have in that part of the file:

VESSEL
    {
        pid = 73f9dec4e74a402ea64d1183ddcb8b55
        name = CommSAT KSO I
        type = Probe
        sit = ORBITING
        landed = False
        landedAt = 
        splashed = False
        met = 62739.0407278273
        lct = 70585.636642262
        root = 0
        lat = -0.0708559885838229
        lon = -97.2394889192516
        alt = 2917405.7211654
        hgt = -1
        nrm = -0.09325099,-0.0001452725,0.9956426
        rot = 0.0007564927,0.3462162,0.0007205357,0.9381542
        CoM = 4.619361E-05,-0.7510172,-0.0001405951
        stg = 1
        prst = False
        ref = 1691954764
        cPch = 
        cHdg = 
        cMod = 0
        ORBIT
        {
            SMA = 3502697.83155638
            ECC = 0.0117003331041419
            INC = 0.0754202425356052
            LPE = 138.336092052635
            LAN = 164.846525659517
            MNA = 1.92694328942951
            EPH = 133324.677370089
            REF = 1
        }

And then all the parts and all. Thanks!

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  • This is where a satellite with it's own propulsion can come in handy.
    – Frank
    Jan 20, 2014 at 5:29
  • 1
    It was all explained here: youtube.com/watch?v=0wXVm3M2I2w - can't acces youtube now, so I'll leave it to you to watch and listen and write an answer here ;) But as @Frank say, a little bit of propulsion is good. Or a docking port so you can attach a tugboat. Last but not least MechJeb is great for cheat-less precision.
    – Mołot
    Jan 20, 2014 at 8:05
  • 1
    @Moot: Ah, you beat me to the obligatory Scott Manley video. Yes, that's probably the best video resource for the problem at hand.
    – MBraedley
    Jan 20, 2014 at 11:58
  • @MBraedley if you can't type ł, type l (lower case L) instead. without either I will not be notified you commented at me.
    – Mołot
    Jan 20, 2014 at 12:05
  • @Mołot: I blame the auto-reply GreaseMonkey script.
    – MBraedley
    Jan 20, 2014 at 12:25

1 Answer 1

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The part most interesting for you is:

    lat = -0.0708559885838229
    lon = -97.2394889192516
    alt = 2917405.7211654

To have a stable geosynchronous orbit, you need to set latitude to 0, so you are over equator. To obtain longitude, simply launch another craft, and keep it in KSC. Read lon from it's save. Proper altitude can be read from Kerbin entry at wiki. Currently it's 2,868.75 km - you are a bit too high, so update accordingly.

Now to the orbit part, you want:

ECC = 0

for exactly round orbit. Also, to avoid confusing your game, you need to set average of periapsis and apoapsis to your new-current altitude. However, when we take into account Kerbin radius, it gets 3 468.75 km, due to Kerbin's ~600km radius:

SMA = 3468750

To be sure you are on equator, nullify inclination:

INC = 0

The tricky part is MNA - Mean anomaly at epoch. If your game will decide to use it instead of lat and long set above, you may find yourself not where you wanted. Experiment with changing it a bit in one way or another.

For easier experiments always edit quicksave. That way you will be able to load updated state with one key. And always backup your persistence file.

For a video tutorial watch this Youtube video. As usual, Scott Manley is your friend.

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