Space radiation cancer risks and uncertainties for Mars missions

Area of Science:

• Space radiation oncology
• Astrobiology
• Radiation risk assessment

Background:

• Human cancer risk from space radiation is poorly understood due to limited radiobiology data for high-energy ions.
• Galactic cosmic rays (GCR) pose significant risks, but projections are hampered by uncertainties in biological and physical factors.

Purpose of the Study:

• To quantify the uncertainty in cancer risk projections for space missions, specifically Mars missions.
• To assess the impact of various uncertainty factors on overall risk estimations.

Main Methods:

• Utilized a linear-additivity model with Monte Carlo sampling from subjective error distributions.
• Incorporated space radiation environment and transport codes for Mars mission scenarios.
• Focused on quantifying uncertainty in risk projections due to knowledge gaps.

Main Results:

• Cancer risk projections for Mars missions exhibit uncertainties of 400-600%.
• Uncertainties associated with quality factors were identified as the dominant contributors to overall risk uncertainty.
• Current safety standards for low-Earth orbit are deemed unacceptable for long-term missions outside Earth's magnetic field.

Conclusions:

• Significant uncertainties necessitate a re-evaluation of safety standards for deep space exploration.
• The shape of the dose-response curve at low dose rates may introduce additional uncertainty in space radiation risk assessment.
• Further research is needed to refine radiobiology data and reduce uncertainties in cancer risk projections for astronauts.