RDV with asteroids without a sweat

[kermand]

Here is a method for rendez-vous-ing and catching asteroids ( or really, any curved ball the universe throws at you inside Kerbin's SOI ). I tested it this week end with class D asteroids and it gave me satisfaction, so i wanted to share. (I have no class E in my vicinity to try it on right now, but look forward to it ).

The problem: asteroids good. Me catch dem. But asteroids often on higly excentric, strongly inclined orbit. Sad. I try to refuel and reuse the same tug as much as possible, but those pesky rocks never have the good manners to match my LKO parking orbit, and more often than not i spent too much fuel reaching them and could not stop them. sad.

The solution : park your tug around the Mun and rendez vous from there.

Here is the process in 10 steps:

1. Have a tug in mun orbit. A Klaw, a Nerva, reaction wheels and lots of fuel, preferably in Mk 1 fuel tanks for better mass ratio.Refuel. For bonus style points, refuel from a mun base.
2. When your target enters Kerbin SOI, look at its trajectory. Its plan will cut the mun's in two places (unless it's quasi-coplanar, in such case you don't need this trick anyway, you lucky person). This means you have one window every 3 Kerbin days to launch your mission.
3. When the mun is aligned with the 'roid's plan, burn like you want to go back to Kerbin. But instead of aiming for the equator and reentry like normal, aim so that Kerbin will slingshot you in the proper alignment. This will require playing with the normal/antinormal vectors and setting your escape velocity accordingly. The advantage here is that a very small nudge inside the mun's SOI can completely change your orbit once the Kerbin slingshot is complete. Not mentioning the Oberth effect goodie you will get at your Kerbin periapsis. Pay attention though to the target orbit's orientation. Depending on that you will have to aim for one side of Kerbin or the other, but again, a small push early will allow for a big difference in the final result.
4. With a proper slingshot, you should reach the target's path with little spending of fuel. You don't have much leeway for timing, so make corrections with radial in/out manoeuvres to meet the target.
5. Normaly, you should be able to rendez vous with only a fraction of your fuel spent. Match velocity, klaw, turn around and burn until your periapsis enters Kerbin's atmosphere. You can now wait for the air to bring down your apoapsis for free.
6. While you are still far from Kerbin and your velocity is low, try to align your inclination. The farer from Kerbin, the easier.
7. When your apoapsis is low enough, bring your periapsis outside of Kerbins atmosphere and voila, you are in LKO with your rock.
8. Bring your tug back to mun orbit, refuel, rinse, repeat.
9. ?
10. Profit !

Edited June 9, 2017 by kermand