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RaDI-N 2 Neutron Field Study (RaDI_N2)
Principal Investigators
Research Area:
Environmental monitoring
Radiation biology
Species Studied
Scientific Name: Species: Not applicable

RaDI-N 2 Neutron Field Study 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.

The objectives of this study are:

  1. 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. ISS).
  2. To repeat the measurements from the RaDI - N1 study, which was conducted on early increments on the ISS, in the same/equivalent locations aboard the ISS: USLab, JEM (Nominal), COLUMBUS, and 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.

The results of Radi-N 1 and 2 study will allow 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.

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Radiation monitoring
Technology assessment

Data Information
Data Availability
Archiving in progress. Data is not yet available for this experiment.

Radiation dose
Radiation measurement

Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Expedition 33 09/16/2012 11/18/2012 63 days
Expedition 34 11/18/2012 03/15/2013 117 days
Expedition 35 03/15/2013 05/13/2013 58 days
Expedition 36 05/13/2013 09/10/2013 166 days
Expedition 37 09/10/2013 11/10/2013 61 days
Expedition 38 11/10/2013 03/10/2014 120 days
Expedition 39 03/10/2014 05/13/2014 64 days
Expedition 40 05/13/2014 09/10/2014 133 days
Expedition 41 09/10/2014 11/09/2014 29 days
Expedition 42 11/10/2014 03/11/2015 121 days
Expedition 43 03/11/2015 06/10/2015 91 days
Expedition 44 06/10/2015 09/11/2015 93 days
Expedition 58 12/18/2018 03/14/2019 85 days
Expedition 59 03/14/2019 06/24/2019 102 days

Additional Information
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Johnson Space Center LSDA Office
Project Manager: Jessica Keune
Institutional Support
Canadian Space Agency (CSA)
Proposal Date
Proposal Source