An account is provided of the main sources of energetic particle radiation in interplanetary space (Galactic Cosmic Radiation and Solar Energetic Particles) and career dose limits presently utilized by NASA to mitigate against the cancer and non-cancer effects potentially incurred by astronauts due to irradiation by these components are presented. Certain gaps in knowledge that presently militate against mounting viable human exploration in deep space due to the inherent health risks are identified and recommendations made as to how these gaps might be closed within a framework of global international cooperation.