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Astronauts are exposed to approximately 50-2,000 millisieverts (mSv) while on six-month-duration missions to the International Space Station (ISS), the moon and beyond. The risk of cancer caused by ionizing radiation is well documented at radiation doses beginning at 50 mSv and above.〔 Related radiological effect studies have shown that survivors of the atomic bomb explosions in Hiroshima and Nagasaki, nuclear reactor workers and patients who have undergone therapeutic radiation treatments have received (low-linear energy transfer (LET) ) radiation (x-rays and gamma rays) doses in the same 50-2000 mSv range. ==Composition of space radiation== While in space, astronauts are exposed to protons, helium nuclei, and high-Z high energy ions (HZE ions), as well as secondary radiation from nuclear reactions from spacecraft parts or tissue.〔 Space radiation is composed mostly of high-energy protons, helium nuclei, and HZE ions. The ionization patterns in molecules, cells, tissues and the resulting biological insults are distinct from typical terrestrial radiation (x-rays and gamma rays, which are (low-LET radiation )). GCRs (galactic cosmic rays) from outside the Milky Way galaxy consist mostly of highly energetic protons with a small component of HZE ions.〔 Prominent HZE ions: * carbon (C) * oxygen (O) * magnesium (Mg) * silicon (Si) * iron (Fe) GCR (galactic cosmic ray)〔(【引用サイトリンク】url=http://helios.gsfc.nasa.gov/gcr.html )〕 energy spectra peaks (with median energy peaks up to 1,000 MeV/amu) and nuclei (energies up to 10,000 MeV/amu) are important contributors to the dose equivalent.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Spaceflight radiation carcinogenesis」の詳細全文を読む スポンサード リンク
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