Thanks. That way it works.
Does that "fire missile once you're at that location" make any sense? In what circumstance can that be senseful?
It is useful for dropping sensor buoys or mines.
I've used it for years now. But thinking about it, it gave me a few brain farts back in the beginning.
Perhaps change the description of the command to "Launch missiles upon arrival" for C#?
"Send message" is also like this. It sounds from the getgo like you're going to send some message to the planet? When really its a very handy command to tell future me what the heck this fleet is supposed to be doing after it finishes whatever it was doing. (past me knows just how forgetful future me can be).
That was my basic idea: launch missiles at the planetary bodies to be able to tell if there are aliens present in the system. The missiles itself have no geosensor, only passive to detect populations.
That way, I would not risk crew and ship senselessly while eploring the system.
You can do it if you wish. I highly recommend if you do, make sure that before you jump into the system you're going to launch your sensor probes, you manually throttle down the speed of the fleet. This will lower the TGs thermal sig. Not much of a point trying to play hide and seek using missile probes, when your fleet is idling with 1500+ thermal sigs.
*Edit, just remembered, there's actually a "Picket(1km/s)" command that when the fleet arrives at its destination, it will drop to 1km/s automatically. Do that before jumping in, and your fleet basically won't have a thermal sig when it pops in for you to fire your missiles. Just don't forget to throttle them back up when you're sending them elsewhere.
Though my experience in using sensor missiles for scouting has been lackluster at best.
On the 1 hand you can build incredibly small missiles that you fire 1 at each planet, and they'll detect for the planet only... but what happens when you jump into a massive system with dozens and dozens? Easy enough to carry, but very tedious to make orders to send everywhere. Also they're not worth much in detecting ships transiting between planets.
To counter this we just build big ones with big sensors. Well now you're making missiles literally the size of fighters, that under perform to a fighter based scout (missile engines are inefficient, can't be throttled, can't have reduced thermal tech. Sensors work the same but require ~20% more weight due to the missile needing a reactor. Can't be reused, can't be sent to scout a different location if the first location was clear).
On top of that, no ship other than maybe a minelayer will be able to launch the things due to their sizes generally being much much larger than you will want on any normal combat ship.