# Can MechJeb do a burn to hit an arbitrary target value?

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I'm trying to use MechJeb to manage the burns needed for my Earth-Moon Aldrin Cycler: KSP Wikivideo.  Unfortunately I currently have a couple funky maneuvers that I can't seem to wring out of MechJeb.

1. Inbound on an elliptical orbit, I want a maneuver node at Earth PE that sets up a Hohmann loop around the moon and returns to Earth PE=3000km.

2. Plane alignment in the leadup to an Earth-Moon Hohmann loop. See images below. I don't think this can be done as a standard AN/DN adjustment. At least not as cheaply as doing it on the inbound trip to the earth.  Problem: In Earth-Moon Hohmann transits any deviation from planar alignment is amplified by the close approaches.  Plane alignment can be fixed quite cheaply by adjusting out-of-plane velocity such that the Earth & Moon PE encounters provide the appropriate tweaks.

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Mechjeb's maneuver node tool will burn to meet whatever the next maneuver node is, if that's what you're asking.  So if you can create the node, it can do the burn.  (Within it's tolerances.)

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> if you can create the maneuver node

That's my problem. I want to program MJ to create a maneuver node with a custom criterion.  The more I think about the problem the more impossible it looks.

My second example above may be achievable if I knew how.  Can MJ create a maneuver node 5 minutes in the future AND use a criterion like "align to plane of Moon."

My first example is even more problematic. I want to create a Node at periapsis that sets the next periapsis based on the real conditions. In my case the periapsis occurs on return from a Hohmann loop.  I think the problem is that MJ would need to iterate to find the solution. If that's even possible MJ would likely need an input like "prograde burn" just to start guessing at the right solution.

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You're probably past what's built-in to MechJeb.  If you really want to automate it, I'd suggest taking a look at kOS:

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Thanks for the reference to kOS.  I will definitely look into it.  ... and kOS is terrific!  Just what I was looking for.

Edited by lfast

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