A Mission to Mars: Prediction of GCR Doses and Comparison with Astronaut Dose Limits

Abstract

Long-term human space missions such as a future journey to Mars could be characterized by several hazards, among which radiation is one the highest-priority problems for astronaut health. In this work, exploiting a pre-existing interface between the BIANCA biophysical model and the FLUKA Monte Carlo transport code, a study was performed to calculate astronaut absorbed doses and equivalent doses following GCR exposure under different shielding conditions. More specifically, the interface with BIANCA allowed us to calculate both the RBE for cell survival, which is related to non-cancer effects, and that for chromosome aberrations, related to the induction of stochastic effects, including cancer. The results were then compared with cancer and non-cancer astronaut dose limits. Concerning the stochastic effects, the equivalent doses calculated by multiplying the absorbed dose by the RBE for chromosome aberrations (“high-dose method”) were similar to those calculated using the Q-values recommended by ICRP. For a 650-day mission at solar minimum (representative of a possible Mars mission scenario), the obtained values are always lower than the career limit recommended by ICRP (1 Sv), but higher than the limit of 600 mSv recently adopted by NASA. The comparison with the JAXA limits is more complex, since they are age and sex dependent. Concerning the deterministic limits, even for a 650-day mission at solar minimum, the values obtained by multiplying the absorbed dose by the RBE for cell survival are largely below the limits established by the various space agencies. Following this work, BIANCA, interfaced with an MC transport code such as FLUKA, can now predict RBE values for cell death and chromosome aberrations following GCR exposure. More generally, both at solar minimum and at solar maximum, shielding of 10 g/cm2 Al seems to be a better choice than 20 g/cm2 for astronaut protection against GCR.

Drug Discovery Targeting Post-Translational Modifications in Response to DNA Damages Induced by Space Radiation

“…Deep space exploration and long-term human space missions are stalled and greatly restricted by hazards, including microgravity and cosmic radiation. Cosmic radiation is among the highest-priority threats to the health of astronauts [1][2][3]. Diverse ionizing radiations existing in the complex space environment, especially those of high linear energy transfer (LET), cause cataracts [4], promote Alzheimer's disease [5], and affect cardiac physiology [6].…”

Radiation Damage in Biomolecules and Cells 3.0

“…In the framework of cancer radiotherapy research, Nowak et al [ 13 ] investigated how to improve the radiosensitivity of lung cancer cells based on Chinese medicine and/or conventional medicine pharmacy drugs by reviewing potential candidates that may show a radio-sensitizing effect on lung cancer cells. Finally, concerning radiation-induced damage at the tissue, organ, and organism level, Ramos et al [ 14 ] predicted astronauts’ doses in the event of exposure to cosmic rays during a long-term mission in deep space, such as a future journey to Mars. The authors exploited an interface between the FLUKA Monte Carlo radiation transport code and the BIANCA biophysical model, which allowed calculating both the RBE (Relative Biological Effectiveness) for cell survival, which is related to non-cancer effects, and that for chromosome aberrations, related to the induction of stochastic effects including cancer.…”

“…A database of simulations was presented for H, He, Li, Be, B, and C isotopes at energies from 0.5 GeV/u down to stopping; the doses deposited in a cell nucleus, as well as the yields of DNA single-and double-strand breaks and their clusters, were predicted to vary among diverse isotopes of the same element at energies < 1 MeV/u, especially for isotopes of H and He. The results may affect the risk estimates for astronauts involved in deep space missions and/or the models of ion-beam biological effectiveness and indicate that radiation protection in 14 C or 10 Be dating techniques may be based on knowledge gathered with 12 C or 9 Be.…”