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“Measurements of the neutron spectrum in transit to Mars on the Mars Science Laboratory”, Köhler et al.
Life Sciences in Space Research 5 (2015) A1
Contents lists available at ScienceDirect
Life Sciences in Space Research www.elsevier.com/locate/lssr
Commentary
“Measurements of the neutron spectrum in transit to Mars on the Mars Science Laboratory”, Köhler et al. Jack Miller Co-Editor The Mars Science Laboratory (MSL) spacecraft carried the Curiosity rover to Mars. While the dramatic, successful landing of Curiosity and its subsequent exploration of the Martian surface have justifiably generated great excitement, from the standpoint of the health of crewmembers on missions to Mars, knowledge of the environment between Earth and Mars is critical. This paper reports data taken during the cruise phase of the MSL by the Radiation Assessment Detector (RAD). The results are of great interest for several reasons. They are a direct measurement of the radiation environment during what will be a significant fraction of the duration of a proposed human mission to Mars; they were made behind the de facto shielding provided by various spacecraft components; and, in particular, they are a measurement of the contribution to radiation dose by neutrons. The neutron environment inside spacecraft is produced primarily by galactic cosmic ray ions interacting in shielding materials, and given the high biological ef-
fectiveness of neutrons and the increased contribution of neutrons to dose with increased depth in shielding, accurate knowledge of the neutron energy spectrum behind shielding is vital. The results show a relatively modest contribution from neutrons and gammas compared to that from charged particles, but also a discrepancy in both dose and dose rate between the data and simulations. The failure of the calculations to accurately reproduce the data is significant, given that future manned spacecraft will be more heavily shielded (and thus produce more secondary neutrons) and that spacecraft design will rely on simulations and model calculations of radiation transport. The methodology of risk estimation continues to evolve, and incorporates our knowledge of both the physical and biological effects of radiation. The relatively large uncertainties in the biological data, and the difficulties in reducing those uncertainties, makes it all the more important to improve both the accuracy and the precision of the physics data.
DOI of original article: http://dx.doi.org/10.1016/j.lssr.2015.03.001. E-mail address: [email protected]. http://dx.doi.org/10.1016/j.lssr.2015.04.006 2214-5524/© 2015 Published by Elsevier Ltd on behalf of The Committee on Space Research (COSPAR).
Contents lists available at ScienceDirect
Life Sciences in Space Research www.elsevier.com/locate/lssr
Commentary
“Measurements of the neutron spectrum in transit to Mars on the Mars Science Laboratory”, Köhler et al. Jack Miller Co-Editor The Mars Science Laboratory (MSL) spacecraft carried the Curiosity rover to Mars. While the dramatic, successful landing of Curiosity and its subsequent exploration of the Martian surface have justifiably generated great excitement, from the standpoint of the health of crewmembers on missions to Mars, knowledge of the environment between Earth and Mars is critical. This paper reports data taken during the cruise phase of the MSL by the Radiation Assessment Detector (RAD). The results are of great interest for several reasons. They are a direct measurement of the radiation environment during what will be a significant fraction of the duration of a proposed human mission to Mars; they were made behind the de facto shielding provided by various spacecraft components; and, in particular, they are a measurement of the contribution to radiation dose by neutrons. The neutron environment inside spacecraft is produced primarily by galactic cosmic ray ions interacting in shielding materials, and given the high biological ef-
fectiveness of neutrons and the increased contribution of neutrons to dose with increased depth in shielding, accurate knowledge of the neutron energy spectrum behind shielding is vital. The results show a relatively modest contribution from neutrons and gammas compared to that from charged particles, but also a discrepancy in both dose and dose rate between the data and simulations. The failure of the calculations to accurately reproduce the data is significant, given that future manned spacecraft will be more heavily shielded (and thus produce more secondary neutrons) and that spacecraft design will rely on simulations and model calculations of radiation transport. The methodology of risk estimation continues to evolve, and incorporates our knowledge of both the physical and biological effects of radiation. The relatively large uncertainties in the biological data, and the difficulties in reducing those uncertainties, makes it all the more important to improve both the accuracy and the precision of the physics data.
DOI of original article: http://dx.doi.org/10.1016/j.lssr.2015.03.001. E-mail address: [email protected]. http://dx.doi.org/10.1016/j.lssr.2015.04.006 2214-5524/© 2015 Published by Elsevier Ltd on behalf of The Committee on Space Research (COSPAR).