It's called a "quantum vacuum plasma thruster" and nobody knows how it works. Or why it works. In fact, most experts are saying it can't possibly work.
NASA has done test bed work, though, and they're claiming it...works. They aren't willing to say why, though.
Oh, to make it even better, they intentionally configured a test rig not to work.
It still worked.
So, is this cold fusion, or is this the future of space travel? It's a rocket engine that requires no "fuel" in the traditional sense - it's powered entirely off of the sun's own electrical field (which means it will probably not be usable as a stardrive, but...)
There's going to be a lot of people rushing to duplicate this one. I'm hoping, obviously, that it's not cold fusion - because a space drive that doesn't need to carry propellent right away makes interplanetary travel much more feasible.