Fog of War and already colonized planets...

[Suicide Junkie]

Heck, it dosen't even take one turn, since you can keep building your other stuff, and one satellite won't make a dent in your construction rate.

[raynor]

I have to constantly remind myself to keep stuff in my building queues so I don't waste the production. I think I would probably tell a planet to build just one satellite and lament the loss of that turn's production.