I would expect that using the RCS is better, just from how powerful it is in general, but it is a lot of mass you\'re trying to accelerate. The only real ways of testing it are functionally the same as just doing the crash again with and without the extra kick. Also, I\'m pretty sure you\'d have to quadruple the mass for a kiloton, 0.5mv^2 and all that. Anyway, sounds like a fun challenge, I throw my hat in with a joke lander I built today, turned out to be unnecessarily heavy at 32.2 tons w/o fuel, but that\'s exactly what this challenge needs! I got it up to 5423.7m/s with the original slightly overpowered (slightly underkerbal?) rocket that got it to minmus with fuel to spare. I\'ll probably try this again with moar power on the final stage. I bet some SRBs would do the job... Anyway, 32.2 * 5423.7 = 174,643 ton m/s In Excalibur terms, that\'s about 0.103 kilotons. Increasing the energy seems a more interesting challenge to me, but I\'m not sure how well the physics in KSP work with that goal (I\'m guessing the answer would always be to drain all your fuel for a heavy impact). It means that maltesh\'s entry, while having a momentum less than 1/3 of mine, has an energy of 0.066 kilotons, damn near 2/3 of mine, due to the high velocity. The momentum challenge does certainly seem to favour the heavier crafts. ~~~Edit~~~ I have a new PB, and it\'s a doozy. A high-velocity landing craft consisting of a pointy cockpit (fer piercin\' them Munrocks), 6 LFTs (1 too many, it turned out, I had half a tank left on impact), a liquid engine, and 104 landing wheels (for safety), with total impact mass of 58.2 tons rendezvous\'d with the Mun at a velocity of 8299 m/s. That\'s 483,001 ton m/s. Also, the energy on impact was 0.434 kilotons. It\'s unfortunate I couldn\'t use the last half tank, I reckon I\'d have cracked 500 ktm/s if I\'d started my burn before entering mun SOI, or if I hadn\'t (foolishly) used the vectoring liquid engine. I use the previous stage to line everything up, I really don\'t need the vectoring. The real key with this was the landing craft. What started as a joke ended up being a really densely weighted dart, surprisingly good for this challenge. Unfortunately, it lags the hell out of my game, and it would be utterly uncontrollable at ~1fps without mechjeb. Also, real Jeb was on board, so it couldn\'t possibly go wrong. I really need something more... single-bodied... to smash into this rock. Anyway, have fun trying to beat this mark! I know I will.