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Space Radiation Cancer Risks and Uncertainties for Mars MissionsProjecting cancer risks from exposure to space radiation is highly uncertain because of the absence of data for humans and because of the limited radiobiology data available for estimating late effects from the high-energy and charge (HZE) ions present in the galactic cosmic rays (GCR). Cancer risk projections involve many biological and physical factors, each of which has a differential range of uncertainty due to the lack of data and knowledge. We discuss an uncertainty assessment within the linear-additivity model using the approach of Monte Carlo sampling from subjective error distributions that represent the lack of knowledge in each factor to quantify the overall uncertainty in risk projections. Calculations are performed using the space radiation environment and transport codes for several Mars mission scenarios. This approach leads to estimates of the uncertainties in cancer risk projections of 400-600% for a Mars mission. The uncertainties in the quality factors are dominant. Using safety standards developed for low-Earth orbit, long-term space missions (>90 days) outside the Earth's magnetic field are currently unacceptable if the confidence levels in risk projections are considered. Because GCR exposures involve multiple particle or delta-ray tracks per cellular array, our results suggest that the shape of the dose response at low dose rates may be an additional uncertainty for estimating space radiation risks.
Document ID
20040088717
Acquisition Source
Johnson Space Center
Document Type
Reprint (Version printed in journal)
Authors
Cucinotta, F. A.
(NASA Johnson Space Center Houston TX United States)
Schimmerling, W.
Wilson, J. W.
Peterson, L. E.
Badhwar, G. D.
Saganti, P. B.
Dicello, J. F.
Date Acquired
August 21, 2013
Publication Date
November 1, 2001
Publication Information
Publication: Radiation research
Volume: 156
Issue: 5 Pt 2
ISSN: 0033-7587
Subject Category
Aerospace Medicine
Report/Patent Number
JSC-CN-6996
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Radiation Health
NASA Center HQS
NASA Center JSC
NASA Center LaRC
Non-NASA Center

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