This is something I stole from another system, and it seems to work pretty well. Every so often, I need the PC's to find a way to accomplish something that my players just aren't thinking of. Often, though, it IS something their characters would know, they're just not enough of a trekkie.
Here's what I do: Set a TN, depending on the complexity of the idea. The more complex the idea, the higher the TN. Have whichever character(s) most likely to hark upon the idea roll 2d6, adding their INT modifier. If they meet or beat the TN; tell them what it is they figure out. If they come close; maybe give them a hint that would lead them down the right path. Falling too far below the TN, and they remain clueless.
Comments or Questions?