Radi-N2 Neutron Field Study (Radi-N2) - 12.17.14
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Radi-N2 Neutron Field Study (Radi-N2) is a follow on investigation designed to characterize the neutron radiation environment aboard the International Space Station (ISS). Eight neutron “bubble detectors” produced by the Canadian company Bubble Technology Industries are attached to fixed locations inside the ISS, including one carried by a crewmember. The objective of this investigation is to better characterize the ISS neutron environment and define the risk posed to the crewmembers’ health and provide the data necessary to develop advanced protective measures for future space flight.
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Bubble Technology Industries, Incorporated, Chalk River, Ontario, Canada
Sponsoring Space Agency
Canadian Space Agency (CSA)
ISS Expedition Duration
September 2012 - Ongoing
Previous ISS Missions
Radi-N1 Increment 20/21
Study is supported by the ISS Radiation Health Working Group in its aim to better characterize the neutron environment aboard the ISS. Better understanding of the neutron contribution will assist in the development of more effective countermeasures. Neutrons are of particular interest to radiation health and protection as neutrons have higher radiation Quality Factor (QF) and since they have not been well characterized by operational monitoring. It has been recognized that neutrons make up a significant fraction (10-30%) of the biologically effective radiation exposure in low-Earth orbit (i.e. International Space Station).
Study is a continuation of Radi-N1 done in Increment 20/21, and will repeat the measurements in the same/equivalent locations aboard the ISS: USLab, JEM (Nominal), COLUMBUS, Node2 (Reserve) The additional data will increase the statistical accuracy of the neutron measurements and also allow comparison of neutron fields at different periods of the solar cycle.
Results of Radi-N 1 & 2 study will allow better understanding of radiation environment aboard the International Space Station. The utilization of newly developed Bubble Detector Spectrometer will help characterize the neutron spectrum on board, and measurements in different ISS locations will provide a means of assessing the neutron field symmetry in different modules of the Station. Measuring the average dose within different segments of ISS will help with development of radiation protection plan for future missions.
Neutrons are nuclear "splinters" produced when cosmic rays strike the atoms of a spacecraft or even the human body. Earlier experiments with Matroshka-R, a "phantom" body, revealed that astronauts absorb larger doses of neutron radiation than expected, possibly from cosmic rays striking atoms in their bodies. Mapping across the ISS will help reveal neutron sources and exposure dangers.
Because they carry no electrical charge, neutrons have greater potential to penetrate the body and damage tissue. Radi-N2 will help doctors understand better the connections between neutron radiation and DNA damage and mutation rates, cataracts that affect some astronauts, and other radiation health issues.
Ground Based Results Publications
El-Jaby S, Tomi L, Sihver L, Sato T, Richardson RB, Lewis BJ. Method for the prediction of the effective dose equivalent to the crew of the International Space Station. Advances in Space Research. 2014 March; 53(5): 810-817.
El-Jaby S, Lewis BJ, Tomi L. A model for predicting the radiation exposure for mission planning aboard the international space station. Advances in Space Research. 2014 April; 53(7): 1125-1134. DOI: 10.1016/j.asr.2013.10.006.