A nanomaterial has been designed to convert radiation directly into electricity: http://technology.newscientist.com/...urns-radiation-directly-into-electricity.html It is said to be upto 20 times more efficient than radioisotope thermoelectric generation. http://nextbigfuture.com/2008/03/direct-conversion-of-radiation-into.html This sounds like 1 MW / L !! I'm wondering if something like this could be used to power a VASIMR rocket? What else could it power? Dune-buggy sized Mars rovers? Space probes are obvious, though. What about things down here on Earth? Mini-submarines? Antarctic land transport? Nuclear-powered pacemakers? Mountaintop communication relays? Battlefield lasers? Plasma-assisted drag reduction for high-speed aerospace craft?