The phenomenological track-structure model of cell damage is discussed. A description of the application of the track-structure model with the NASA Langley transport code for laboratory and space radiation is given. Comparisons to experimental results for cell survival during exposure to monoenergetic, heavy-ion beams are made. The model is also applied to predict cell damage rates and relative biological effectiveness for deep-space exposures. Katz, Robert and Cucinotta, Francis A. and Wilson, John W. and Shinn, Judy L. and Ngo, Duc M. Langley Research Center RTOP 199-04-16-11...