There is a proposal for a manned mission to Ceres using nuclear powered ion engines: http://news.nationalgeographic.com/news/2013/11/131118-ceres-asteroid-solar

There is a proposal for a manned mission to Ceres using nuclear powered ion engines: http://news.nationalgeographic.com/news/2013/11/131118-ceres-asteroid-solar-system-space-science/ http://news.nationalgeographic.com/news/2013/11/131118-ceres....