Prior to the human exploration of Mars or long duration stays on the Earth s moon, the risk of cancer and other diseases from space radiation must be accurately estimated and mitigated Space radiation, comprised of energetic protons and heavy nuclei, has been show to produce distinct biological damage compared to radiation on Earth, leading to large uncertainties in the projection of cancer and other health risks, while obscuring evaluation of the effectiveness of possible countermeasures Here, we describe how research in cancer radiobiology can support human missions to Mars and other planets

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Heavy ion carcinogenesis and human space exploration

National space agencies are planning a human mission to Mars in the XXI century. Space radiation is generally acknowledged as a potential showstopper for this mission for two reasons: a) high uncertainty on the risk of radiation-induced morbidity, and b) lack of simple countermeasures to reduce the exposure. The need for radiation exposure mitigation tools in a mission to Mars is supported by the recent measurements of the radiation field on the Mars Science Laboratory. Shielding is the simplest physical countermeasure, but the current materials provide poor reduction of the dose deposited by high-energy cosmic rays. Accelerator-based tests of new materials can be used to assess additional protection in the spacecraft. Active shielding is very promising, but as yet not applicable in practical cases. Several studies are developing technologies based on superconducting magnetic fields in space. Reducing the transit time to Mars is arguably the best solution but novel nuclear thermal-electric propulsion systems also seem to be far from practical realization. It is likely that the first mission to Mars will employ a combination of these options to reduce radiation exposure.

http://alpha.sinp.msu.ru/~panov/Lib/Papers/MARS/1-s2.0-S2214552414000042-main.pdf

Space radiation protection: Destination Mars

Fragmentation cross sections of Fe 26+ , Si 14+ and C 6+ ions of 0.3 10 A GeV on polyethylene, CR39 and aluminum targets

Shielding is the only practical countermeasure for the exposure to cosmic radiation during space travel It is well known that light, hydrogenated materials, such as water and polyethylene, provide the best shielding against space radiation Kevlar and Nextel are two materials of great interest for spacecraft shielding because of their known ability to protect human space infrastructures from meteoroids and debris We measured the response to simulated heavy-ion cosmic radiation of these shielding materials and compared it to polyethylene, Lucite (PMMA), and aluminum As proxy to galactic nuclei we used 1 GeV n iron or titanium ions Both physics and biology tests were performed The results show that Kevlar, which is rich in carbon atoms (about 50% in number), is an excellent space radiation shielding material Physics tests show that its effectiveness is close (80-90%) to that of polyethylene, and biology data suggest that it can reduce the chromosomal damage more efficiently than PMMA Nextel is less efficient as a radiation shield, and the expected reduction on dose is roughly half that provided by the same mass of polyethylene Both Kevlar and Nextel are more effective than aluminum in the attenuation of heavy-ion dose

M. Briccarello

Papers

Accelerator-based tests of radiation shielding properties of materials used in human space infrastructures.

Passive Radiation Shielding Investigations in Low Earth Orbit and in an Accelerator