MOSCOW – A nuclear-powered spaceship that can carry passengers to Mars and beyond may sound like science fiction. But Russian engineers say they have a breakthrough design for such a craft, which could leapfrog them way ahead in the international race to build a manned spacecraft that can cover vast interplanetary distances. They claim they’ll be ready to build one as early as 2012. In a meeting with top Russian space scientists Wednesday, President Dmitry Medvedev gave the nuke-powered space craft a green light and pledged to come up with the cash to cover its $600-million price tag. “It’s a...