One of the hardest problems of manned long-term space travel is figuring out how to protect the crew from harmful cosmic radiation. You could, of course, encase the astronauts in thick sheets of metal, but that would make the spacecraft impractically heavy, as well as ruin the view.
Another approach is to create a bubble of charged plasma around the spaceship, which could deflect the cosmic rays just as our planet's electromagnetic field prevents Earthlings from getting cooked. This 2006 article from the New Scientist magazine describes how scientists are working on a system by which hydrogen is subjected to high voltage and broken down into its constituent protons and electrons, which are then sprayed out into space. The plasma would be contained by an electrified wire mesh around the craft.
