How to get to asteroids?

[jdsutton]

I just can't seem to adjust the maneuver nodes finely enough to intercept an asteroid. I can transfer to other planets easily enough, since they have gravity to grab me and pull me in. How do you hit that tiny target when it has such a huge orbit? Any tips?

[SpenSpaceCorp]

Rendezvousing with objects in Kerbol orbit is basically the same as rendezvousing with say a space station in Kerbin Orbit, it is just tougher because there is more space to traverse, but the principles are the same. I suggest escaping Kerbin first, then setting the asteroid as a target and rendezvousing as you normally would (on a larger scale of course) from there. Or alternatively, you can timewarp ahead until an asteroid enters Kerbin's sphere of influence and go from there.

It is just tougher manipulating the maneuver nodes from orbit around Kerbin as there is no sphere of influence to work off of, and as such, instead of a few hundred or thousand kilometers radius of a sphere, you have maybe a hundred meters or less with an asteroid.

Hope that helped!

[Starstrider42]

Are you using the "Set as Target" function in map view? That should tell you how close your intercept orbit is and help you fine tune it.

[LiveHereNow]

I too am struggling with asteroid rendezvous. If anyone knows the best order of "steps" for large-scale rendezvous, that would be great to learn. I tend to just tweak orbits to rendezvous when around a celestial body, but it's inefficient and I end up w/ a losing battle (fuel please?) on the larger scale of Kerbol orbits.

[ScottyDoesKnow]

I did some really complicated stuff to intercept an asteroid just as it entered SoI, but then there were problems and I was able to get another ship up and rendezvous'd with a couple days before periapsis. All I did was launch into the same plane, then added a maneuver node to push my apoapsis towards about halfway between where the asteroid was and its periapsis. I did have to tweak a bunch to get the closeset maneuver to appear and it jumped around a lot, but I ended up with a 350km closest approach. About 900m/s burn for that and then 150 to match velocity. At that point it was just a normal rendezvous.

[Kasuha]

1/ track the asteroid in tracking station

2/ put your ship on launchpad

3/ select the asteroid as target

4/ time warp till the asteroid is on the horizon of your navball

5/ launch and perform gravity turn towards target prograde/retrograde, whatever is more eastern (results in inclined orbit)

6/ circularize

7/ draw and execute a maneuver which closely escapes Kerbin SOI and has close encounter to the asteroid at about half its trajectory towards Kerbin intercept (the escape direction is usually towards or slightly "behind" the asteroid)

8/ after exiting Kerbin SOI perform standard rendezvous procedure

[Francesco]

For asteroids on an impact course with Kerbin, I've found that this is a good method:

1. Wait for the asteroid to be at the height of Minmus's orbit (~ 50,000 to 45,000 km)

2. Launch into a low Kerbin orbit on the correct orbital plane (you can use a probe on an equatorial orbit to know the asteroid's inclination)

3. Create a maneuver node which puts your apoapsis at roughly 20,000 km

4. Halfway through the way out, create a correction maneuver fiddling with all three axis to get a 100-200 km close encounter (this usually take less than 150 m/s of delta-v)

5. Perform a number of subsequent correction burns to get as close as possible to the asteroid (5-10 km)

6. Upon encounter, cancelling all your relative velocity will take about 700 m/s - know your TWR to time it precisely, as you will be travelling almost orthogonally to the asteroid

7. Even if by now you're still several kilometers apart, imparting a 20-30 m/s push will close the distance in a few minutes

8. Profit!