Gaius

Don't know if it's related to your problem, but only the first MODULE section here should be added to a part to give it MechJeb functionality. The second one is specific to the AR202 case and should never be used on other models.

Oh wow, I didn't even know that was possible. All of my collisions or near collisions have resulted from an extremely accurate Hohmann transfer followed by a match velocity, and I end up basically coming in with my engines pointed at the target, burning to match velocity instead of following the line straight through the target and out the other side. The fact that the "closest approach" match velocity option usually stops you a bit after the closest approach makes this an entertainingly disastrous rendezvous. A bit before would be perfect. I suspect this is related to the way MechJeb executes nodes. A perfect orbit change node is an instantaneous change in velocity at the specified node. Since that's not possible, it's usually simulated by starting a burn half the length of the burn before the node is reached, thus a 10 second burn starts five seconds before the node and ends five seconds after. This has more or less the same effect as the instantaneous change would. The problem, I suspect, is that MechJeb doesn't quite do that. It starts the burn half the estimated burn length at full throttle before the node, which is perfectly correct if you're going to full burn the maneuver. But it doesn't do that, rather, as it gets close to the end, it throttles back and fine tunes. This extends the length of the burn on the plus side of the node to longer than the minus side. To compensate for the way it ends burns, I think it would need to start its burns a tiny bit earlier. But of course since it has no idea how much fine adjusting its going to do at the end, it really has no way to knowing exactly when to start. Or I could be completely wrong. I'm not a rocket scientist. In any case, the end result is, collision course or not, for some reason, when you tell MechJeb to match velocities at closest approach, it usually only succeeds in matching velocities a bit after closest approach. On those cases where you got that perfect rendezvous, a bit before would be highly preferable (unless you *want* an entertainingly disastrous collision -- this is what we all play they game for anyway, right? xD) and a way to set, say, "match velocities X meters before closest approach" would be awesome.

Are you using the latest dev build? IIRC, the "official" 2.0.7 includes a bug where if you add MechJeb to a command module (the root of your ship, rather than using an attachment part like the AR202), you lose settings.

Protip: spaceships have no breaks. Pressing 'X' just cuts your engines. Since the problem is that it's firing retrograde thrusters too late and you're on a collision course with the station, pressing 'X', shutting down the thrusters that are trying to slow you down, will cause you to crash sooner and with greater velocity. Very bad idea... What you want to do is disable the autopilot and then try to divert your course to miss the station. Of course, you're not going to be pointed the right way to do that optimally, and gods help you if your ship doesn't turn well. In short, by the time you realize you're on a collision course, there may be nothing you can do but hit F9 and hope you last quicksave wasn't too long ago...