How would you rendezvous with this asteroid?

[Pwnstarr]

First asteroid capture attempt - I can get to other planets and moons just fine, but polar orbits are my weakness. I'm having a little trouble. Asteroid is coming in on a polar trajectory but will impact the atmosphere. I tried launching south and coming around so I can maneuver to rendezvous with it... but having a little difficulty. I only have a ascending node and the target markers make no sense to me. Suggested strategy?

[Guest]

Launch your craft into a polar orbit aligned with the asteroid's orbit, in the correct direction. Then perform a rendezvous as normal. Maneuver nodes will help. The target markers there are closest approach; you have a lot of time left before the asteroid will be anywhere near rendezvous so you might want to extend your apoapsis towards it. The ascending node is enough to get you aligned with the asteroid's orbit.

[Vanamonde]

This how-to question has been moved to the how-to sub-forum.

[Taki117]

I would actually aunch a rocket into an orbit that is Opposite of the asteroids orbit. Also, while it's not a tutorial,

Has a nice explination on to how to do these things.

[Pwnstarr]

Thanks for the advice but couldn't figure out how to meet the asteroid for the life of me even after launching both ways and playing with maneuver nodes for hours, I guess you have to get it in interplanetary space, this was already in Kerbin's SOI.

[Kasuha]

Simple but spends more dv:

1/ put a maneuver at the marked inclination point on your orbit

2/ pull normal (purple triangle) until you match inclination with the asteroid

3/ execute that maneuver

4/ put a maneuver slightly south of approximate place of asteroid's periapsis

5/ pull prograde until closest approach markers meet in single point

6/ execute that maneuver

7/ perform standard rendezvous at the meeting point

Less dv, but harder: do the same except in single maneuver. Put a maneuver at inclination point and keep pulling prograde while adjusting normal to keep closest approach markers displayed until they meet. You may need to add some radial out component to get the intercept at greater distance.

Edited May 12, 2014 by Kasuha

[Sirrobert]

Personally I like catching asteroids outside of Kerbin SOI.

Eliminates the polar problem, and even lets you turn a polar capture into a neat equatorial one while it's still cheap to do so

[Superfluous J]

I find it easier to catch them in Kerbin's SOI, but at the edge. I made a tutorial for how I do it.

[Pwnstarr]

I find it easier to catch them in Kerbin's SOI, but at the edge. I made a tutorial for how I do it.

Good tut... Thanks!

I guess i shouldnt wait until the asteroid is less than 16 days from impact to launch an intercept mission

Edited May 12, 2014 by Pwnstarr

[Superfluous J]

I guess i shouldnt wait until the asteroid is less than 16 days from impact to launch an intercept mission

That does make it more difficult, but the slow trip to near Kerbin's SOI is about 10 days so you've probably got a single shot.

I'd do what I do in that video, but burn up to about 8 days to apoapsis, so in 2 orbits you'll meet the asteroid. You can tweak the intercept after the first orbit.

Harder than the optimal set-it-up-months-before plan, but essentially the same idea.

Good luck!

[Sean Mirrsen]

My solution for the problem last time it happened was to extend the apoapsis towards the asteroid, then adjust inclination at the apoapsis and catch the asteroid somewhere on the return. It takes some fiddling with the maneuver nodes to properly plan, but you want your time to apoapsis to be half the time to asteroid's periapsis at most, otherwise you'll miss it. If you've aligned the orbit correctly, once you're at the apoapsis of your orbit it should be much easier to plan an intercept.

[Graylag]

So, you have problem with matching orbit with just right orbital parameters, right? If you have enough time I would try radicaly different approach. Launch into low circular zero inclination orbit and then perform bi-elliptic orbit plane transfer. With a little fiddling you have much more precise control over final orbit and since you need highly elliptic orbit anyway, you could actually do it with less deltaV than by launching directly into polar. Timing is little tricky though

I use bi-elliptic for asteroids every time