Radi-N2 Neutron Field Study (Radi-N2) - 11.22.16

Overview | Description | Applications | Operations | Results | Publications | Imagery

ISS Science for Everyone

Science Objectives for Everyone
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 crew member. The objective of this investigation is to better characterize the ISS neutron environment and define the risk posed to the crew members’ health and provide the data necessary to develop advanced protective measures for future spaceflight.
Science Results for Everyone
Data from detectors placed in four modules of the space station showed good agreement with the neutron exposure measured in previous studies; changes in location and altitude of the space station and increased solar activity caused no notable change in the measurements. Additional experiments showed that the neutron exposure measured by the Radi-N2 detectors was lower inside a spherical phantom (made of tissue-equivalent material) than outside the phantom. This agreed with Monte Carlo software simulations performed on the ground. The Radi-N2 experiment is ongoing and measurements are planned up to 2020.

The following content was provided by Leena Tomi, Martin B. Smith, and is maintained in a database by the ISS Program Science Office.
Experiment Details

OpNom: Radi-N

Principal Investigator(s)
Leena Tomi, Canadian Space Agency, Saint Hubert, Quebec, Canada
Martin B. Smith, Bubble Technology Industries Inc, Chalk River, Ontario, Canada

Vyacheslav A. Shurshakov, Institute of Biomedical Problems, Moscow, Russia

Bubble Technology Industries, Incorporated, Chalk River, Ontario, Canada

Sponsoring Space Agency
Canadian Space Agency (CSA)

Sponsoring Organization
Information Pending

Research Benefits
Information Pending

ISS Expedition Duration
September 2012 - March 2016; March 2016 - February 2017; March 2017 - September 2017

Expeditions Assigned

Previous Missions
Radi-N1 (Increment 20/21)

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Experiment Description

Research Overview

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 assists 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 increases 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 and 2 study allows better understanding of radiation environment aboard the ISS. 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.

Information Pending

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Space Applications
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.

Earth Applications
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.

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Operational Requirements and Protocols
Information Pending

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Decadal Survey Recommendations

Information Pending

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Results/More Information

At the time of writing, the neutron exposure measured by the ongoing Radi-N2 experiment is similar to the previous Radi-N measurements conducted in the same locations within the ISS. The data show that changes in ISS location, altitude, and solar activity do not appear to create a notable increase or decrease in neutron passes through the bubble detectors. This agrees with earlier bubble-dosimeter readings in the Russian segment, suggesting that these potential influences have little effect on the neutron field in the ISS. Additional experiments concluded that the neutron exposure measured by the Radi-N2 detectors was lower inside a tissue-equivalent, spherical phantom than outside the phantom. This is in agreement with ground-predicted Monte Carlo software simulations. The Radi-N2 experiment is planned to continue until 2020; conclusions from the experiment will be made following an analysis of the complete set of data. (Smith MB 2016)

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Results Publications

    Smith MB, Khulapko S, Andrews HR, Arkhangelsky VV, Ing H, Koslowsky MR, Lewis BJ, Machrafi R, Nikolaev IV, Shurshakov VA.  Bubble-detection measurements of neutron radiation in the International Space Station: ISS-34 to ISS-37. Radiation Protection Dosimetry. 2016 March; 168(2): 154-166. DOI: 10.1093/rpd/ncv181. PMID: 25899609.

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Ground Based Results Publications

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ISS Patents

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Related 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. DOI: 10.1016/j.asr.2013.12.022.

    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.

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Related Websites

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NASA Image: ISS034E034507 - Canadian Space Agency (CSA) Chris Hadfield holding bubble detectors for the Radi-N2 experiment.

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image NASA Image: ISS035E031921 - Radi-N2 detector floating on board the International Space Station.
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image NASA Image: ISS039E011243 - View of eight Radi-N2 Neutron Field Study (Radi-N2) bubble detectors still packed in their case.
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