One idea I came up with was adopting an old gambling game, "Gluckhaus." Gluckhaus was a German game where soldiers rolled 2d6 and got rewards based on what was rolled. 2 and 12 allowed the player to basically sweep the board, 4 goes to the house, and 7 always goes to the board. Other rolls lead the player to put a coin onto the square (if it is empty) or pick a coin up (if it is not).
My thought is that this arrangement leaves 7 squares unoccupied: 3, 5, 6, 8, 9, 10, and 11. This matches up nicely with all the sets of seven I've come up with already. One could allow the player to arrange seven tiles matching up with the seven planets onto the unoccupied board squares once per quest. The player then gets a number of tokens/coins equal to their technique square, analogous to the size of a card player's hand or chess piece army. The player can roll the dice and then put a coin on the corresponding square to occupy it.
Any coin that matches up with one of the seven planets could grant a standing bonus to anything associated with that planet including skills. Sacrifice a coin (remove it from the game altogether) and you can add that element to any scene, or change that sort of element in a scene. The 2 or 12 would clear the board as in the original game and return all coins to the player's hand, allowing the player to place them again. 7s could be used as a sort of generic "wildcard," perhaps offering a generic bonus to all mechanical skills or something of that nature.
This mechanic would allow players to build the "framework" they operate in for each quest. If you think it is going to be a warlike adventure, then Mars should probably go on a high frequency square like 6 or 8. If Water is going to be important, then maybe Venus goes on one of those squares. The player actually "builds" the board they'll play on throughout the adventure.
One downside to this mechanic is that it requires a lot of thought from the player up front: the critical part is arranging the seven bonus squares onto the right numbers, not the actual rolling of the dice. Also, one would have to create some sort of mechanic to prevent the player from just "spamming" everything down at once or multiple times to create the "ideal" setup of coins on the board. For example, you could give an initial large benefit (maybe playing the token allows the player to add something to the scene), then the static existing benefit, then another benefit when the coin is sacrificed.
I am not committed -- this was definitely just an idea for this sort of mechanic. I'm hoping to stumble across a Renaissance game that fits my theme a bit better. Medieval philosophy did not necessarily encourage themes like, "Man can change the physical world through application of human ingenuity," but the Renaissance seems like a better bet for that sort of idea.