Performing a rendevous with a object that is in a slanted/oval/hohmann orbit?

[MissStabby]

Currently i have a poor kerbalnaut that fell of his spaceship when i was fumbling around on my way to the mun.

Though currently he is in a slanted and eliptical orbit that has a periapsis close to kerbal (around 80km) and a apoapsis somehere between kerbal and the mun.

All tutorials online tell about how to do rendevous manouvres on near perfect orbits that have no inclination and a very low eccentricity.

Also since the kerbal is on EVA there's no mechjeb to tell me the exact inclination values of his orbit.

So how can i most efficiently rendevous with a object that is in a very "weird" orbit?

[Cykyrios]

Well, my own tutorial (

) also shows a circular orbit as an example, but you can use the lower-left cells from my spreadsheet (download link is in the video's description) to compare two elliptical orbits.

You have to make sure you get into an orbit that is almost exactly the same as your target's, and then follow the instructions of the video to rendezvous.

Good luck!

[Bluejayek]

You really don't need to use all that math, unless you want time critical rendezvous. I don't bother, and instead this is my rendezvous plan: I get into an orbit that is in the same inclination, with aproximately the same periapsis and apoapsis as my target. Then, if I am behind in the orbit I lower my periapsis so that I orbit more quickly and wait to catch up. Once I get close, you bring your periapsis closer up so you don't overshoot. Then, when you are within 1-5km (your choice really), burn towards the target as you see it and slowly do the fine rendezvous.

If you are in front of the target in the orbit, just raise your periapsis instead to go slower. This works for any orbit. It can take a large number of orbits to complete though, so be patient

[Markus Reese]

If he is coming in near 80, you won't be able to get a sub orbit on that side of the planet easily. Your best bet would be have a circular orbit of kerbin and wait for him to get in close. He will pass by close and start to fly away again, at which time you can, at the kerbal's periapsis, elongate your own orbit. if you are cutting inside of the kerbal's, you will begin to catch up. How much to elongate your orbit all depends on the difference in speed. If you build a rocket with tons of extra fuel, once you are at your Ao, it isn't to hard to play chase around since the orbital velocities are so low. This of course depends how far out the kerbal's Ao is. The toughest part about a capture like this is if you are playing the chase around, then you might end up flying right past. But plenty of time for the focused pilot to make corrections.

Edit: Personally, a nice rescue ship I find to be the three man capsule. (trick is getting the other one off) For your seeker stage, the 45 maneuvering engine (not the small stock 1m and not the big one, that nice medium) mounted to a tank with four supply tanks around it should be able to get the job done with more than enough fuel left. If you have your original craft the kerbal fell off of, can also have him hang on and try flying him back to meet up

Edited August 26, 2012 by Markus Reese

[Vanamonde]

I haven't tried this yet, but shouldn't the process be almost exactly the same? As long as your apses line up on both orbits, won't other factors cancel each other out?

[Cykyrios]

That's right, just line up the orbits, and either follow my method or do it the fuel-economic, but time-consuming way of adjusting Pe/Ap by a few km until you are close enough to rendezvous.