Probably... but it's still an intriguing idea! Especially since their pressurized gas proposal already calls for a sealed cavity; maybe there actually is poten

Probably... but it's still an intriguing idea! Especially since their pressurized gas proposal already calls for a sealed cavity; maybe there actually is potential there. (Of course, there would probably be a significant PR cost too.) That said, they can already get more weight by making the weight taller, so density likely isn't a huge benefit. Whatever's the cheapest cost/kg (and without the other issues of Uranium) would probably be best.