> This is true, but don't you also think that once extraordinary claims have this much publicity they warrant extraordinary investigation? If for no other purpose than to prove it wrong?

Absolutely, I'd be surprised if it wasn't happening already, within nasa and around the world. I'm guessing they're being a lot more thorough though, controlling for more variables and trying more permutations (different engine sizes, different materials, etc) to try to either isolate the cause or to rule some out. I'd suspect anything less would risk the experimenters being labeled as cranks, that's why we're not seeing direct replication efforts.