Sooo.... If the Asteroid is going to hit.... how do you match orbit?

[NeoMorph]

I know you have to go out and match up the orbit as you are looping back to Kerbin but I haven't a clue how to actually plot the trajectory in KSP.

Any help would be awesome.

[Lone K.]

It's like any ordinary rendezvous, but you have to plan further ahead than a normal rendezvous, because these things can whiz by at hundreds of meters per second faster than your ship is going currently. Just get ahead in the asteroid's trajectory (after its periapsis in Kerbin orbit). This might be some small details, but I assure you that it'll help in your endeavors.

[NeoMorph]

I think I have it sussed... I just hadn't had their orbits appear in the normal map view until just now.

[Xeutack]

1: Escape Kerbin SOI

2: Set asteroid as target

3: Shoot prograde (assuming the asteroid is coming from a more distant orbit) until you cannot get the approach any closer

4: Adjust your plane (using the pink maneuvre tools) to put a node on top of the closest approach. This can be done in combination with step 2.

5: It is going to be very difficult to get closer than like 20,000km at first because every slight engine burst will change the distance tremendously. Once you are relatively close though, warp forward to a closer point and adjust your trajectory again using the maneuvre tool to try and get closer to the roid. The closer to the roid, the less sensitive the periapsis is to engine bursts.

6: Repeat step 5 until you have a periapsis maybe 10km from the asteroid.

7: Warp until the distance to the asteroid is around 100km. Click on the velocity on top of the nav ball until it displays your velocity relative to the target velocity. This will be around 1500 m/s. Point the ship retrograde (while still having the navigation relative to the target) and brake. Depending on the power of your engines, you may want to break earlier or later than 100km. We want to have elimated our relative velocity to the target as close to the periapsis as possible. Brake repeatedly to maintain control and reduce the velocity, so that when the distance to the asteroid starts to increase rather than drop, you can nullify the relative velocity completely.

8: Once the relative velocity is 0 m/s, point towards the target and fire to maybe 50m/s - then turn the ship retrograde ready to brake again.

9: Once once the distance to the roid again starts to increase rather than drop (or if you randomly actually exactly hit it and are getting to close to it), kill the relative velocity again.

10: Repeat step 8 and 9 again (but with less speed and more care the closer you get) until you are close enough to the roid to use rcs.

11: Click the roid, right click and select Target centre of mass.

12: If you are in doubt where to push it, approach it and grab it from the sun side, so you won't run out of power.

13: Deploy the grabbing tool and target the centre of mass - hit the roid with around 0.5m/s or less.

14: If your prograde node now doesn't allign with the target node, the asteroid will spin if you start your engines. You can right click the grabbing tool and select "release pivot" and adjust your prograde so they allign. Then relock it.

15: Happy pushing.

[Superfluous J]

I detailed my 7(ish)-step plan in a video I posted just last night. I don't get a collider in this vid but this plan will work for ANY asteroid that enters Kerbin's SOI, whether it's not even entering Minmus' orbit, or destined to crash into Kerbin.

[airelibre]

Can you not do anything once the asteroid is within Kerbin's SOI?

[MalfunctionM1Ke]

One Clue would be to Keep your Rendezvous angle as shallow as possible.

When you are reaching the Asteroid in a 90° angle (exaggerated) you have to Change your direction AND catch up with the Asteroid.

The best way to do it would be to have the Asteroid catching up on you while it is on its way to Impact Kerbin.

So you only have to cancel out all your relative velocity in one direction.

But that is only my quick Imagination. I have never done such a Thing.

[Sirrobert]

I detailed my 7(ish)-step plan in a video I posted just last night. I don't get a collider in this vid but this plan will work for ANY asteroid that enters Kerbin's SOI, whether it's not even entering Minmus' orbit, or destined to crash into Kerbin.

That's a pritty damn good tuturial, thanks

[O-Doc]

Can you not do anything once the asteroid is within Kerbin's SOI?

This is what I've come up with.

1. Get an orbit in the same direction and plane as the 'roid.

2. Set it as a target and use maneuver node to make burn out to about 2/3 distance.

3. Unset maneuver node(which gets an intersect point) and burn pro or retro to get the target intersect over your periapsis.

4. Adjust intersect point past your periapsis the same distance as the distance from your periapsis to Kerbin's core.

5. Travel to your apoapsis and make course adjustments in the standard rendezvous manner as you near the 'roid. Usually this will mean working the retro side of your navball to speed up into the roid.

The main thin is to flip your thinking to work backwards half an orbit's time in the future.

[airelibre]

Can you not do anything once the asteroid is within Kerbin's SOI?

...........