Can MechJeb land a spacecraft at precise coordinates?

[Spark Plug]

I'm attempting a base on Minmus by launching each module from Kerbin separately and then landing them next to each other. Ideally I would like each lander to end up within 50 meters of each other so that I can link them up with winch cables (for resource transfers, but mainly to give the appearance of power lines).

Anyway, I want to know whether the MechJeb mod is currently capable of such precision. I have a general idea of what the mod is meant for, but I've never actually made use of it. Is MechJeb really able to land a craft on another moon/planet at a specific location? I'm reading up on the mod and watching tutorial videos now, but I'd like to hear some testimonies or experiences from someone.

[jwenting]

usually, it can. But you'd best start the landing autopilot from a 100km orbit or it becomes less accurate with less space to work with.

Starting it in an orbit close to flying over the intended landing site also helps.

It can in fact be so accurate at times that telling it to land at the exact coordinates of another ship on the ground will put you right on top of that ship, with predictable results.

[Seret]

50m might be a bit iffy, but you can certainly get damn close. For that kind of accuracy the main thing throwing you off would probably how accurately you could place the landing target marker.

Tbh on Minmus it costs so little to get airborne that you shouldn't have any trouble with or without Mechjeb. Even if you're several km out you could just do a short hop to your destination.

[goldenpeach]

When I use mechjeb to land near another vehicle(e.g: putting the munar lander near the rover sent before), it usually land within 10 meter of the target(but it doesn't bother me: I put coordinate that would make it land 50 meters away from the rover, just in case).

[Spark Plug]

...telling it to land at the exact coordinates of another ship on the ground will put you right on top of that ship, with predictable results.

For that kind of accuracy the main thing throwing you off would probably how accurately you could place the landing target marker.

I'm planning for one of my existing crew on Minmus to set a flag down where I want the next ship to land. Other than that, he can just stand where I intend to land, then I take his coordinates and punch those numbers into the autopilot.

Tbh on Minmus it costs so little to get airborne that you shouldn't have any trouble with or without Mechjeb. Even if you're several km out you could just do a short hop to your destination.

I know this is true but I find it a little risky to rely on RCS thrust to move my ship laterally while my landing engines keep my vertical velocity steady. But if you're talking about a quick burn to make a low parabolic arc to my target, I can consider that as a potential plan.

Thanks for the reply, you two!

I've seen video demonstrations of MechJeb at work, and your advice regarding target markers helps assure me that this is a viable procedure.

[Seret]

I know this is true but I find it a little risky to rely on RCS thrust to move my ship laterally while my landing engines keep my vertical velocity steady. But if you're talking about a quick burn to make a low parabolic arc to my target, I can consider that as a potential plan.

Whatever you feel confident piloting! Personally I would just use main engines. Target the destination and use the navball. Minmus is pretty forgiving for wonky landings, and there's no reason you couldn't do several tentative little hops to get there.

[Jacam]

I use the same method that Spark Plug uses; plant a flag and then target the flag with MechJeb. I find with landers, MechJeb can freak out a little bit when below 2km or so, and I tend to take over at the point to get a nice smooth landing.

[Uncle Mort]

Close enough for you?

[Eric S]

Whatever you feel confident piloting! Personally I would just use main engines. Target the destination and use the navball. Minmus is pretty forgiving for wonky landings, and there's no reason you couldn't do several tentative little hops to get there.

Sounds like me, for short hops, I tend to use the main engine to counter most of the weight and then use RCS to more precisely control the surface velocity and altitude. Hopping four story colony stacks on Minmus using that technique can be interesting but works. :-)

[Capt. Hunt]

Personally, I wouldn't mind if mechjeb had adjustable accuracy in the landing autopilot, There are times when I do need to land right next to something, but there are also times when a few Km don't make a difference and I could use the extra Delta-V that mechjeb wastes while trying to put the ship down right on top of the target coords.

[wdsmith3]

I have a flag planted in my landing zone and mecjeb almost always puts the ship right on top of the flag