For Graviton tech since it is extremely hard to do multiple levels of it, or at least to do higher levels safely, due to the cost of energy required tripling, I would suggest doing a Small Increase on the Chance of Moon Destruction missions or a Small Decrease in chance of losing your RIP. This being because the increasing of Graviton research level could be seen as you improving the Strength of a graviton beam, which would inflict higher amounts of Force pulling the moon in on itself.