This Hinode/EIS spectrum was obtained between wavelengths of 240-290 Angstroms (24 to 29 nanometers), and shows numerous lines contributed by ions such as iron for which 14 electrons have been removed (FeXV) due to the high-temperature atomic collisions. (Courtesy George Doschek, Hinode/EIS and NRL)
The largest, single, challenge for astronauts traveling to Mars will be to overcome exposure to solar storms and radiation.