Author ORCID Identifier
0000-0003-4639-7990
Date of Graduation
8-2020
Document Type
Dissertation (PhD)
Program Affiliation
Medical Physics
Degree Name
Doctor of Philosophy (PhD)
Advisor/Committee Chair
Stephen Kry
Committee Member
Charles Willis
Committee Member
Fada Guan
Committee Member
Jingfei Ma
Committee Member
Leif Peterson
Abstract
Exploration of interplanetary space presents dramatic hazards to human survival.
Space radiation hazards outside the protection of the Earth’s magnetosphere can
produce both acute and chronic health risks and thus become limiting factors for
NASA’s planned mission to Mars by the 2030s. Radiation exposure on a Mars mission
is delivered primarily by high energy ions from galactic cosmic rays and moderate
energy protons from solar particle events. The chronic radiation dose due to galactic
cosmic rays on a typical Mars mission is on the order of 1 Sv, and additional acute
radiation dose from solar flares can reach over 4 Sv, which is a potentially lethal dose.
Hence radiation protection is a critical concern on these types of missions.
Various methods of radiation shielding have been proposed, from simple passive
shielding via materials such as water, polyethylene, or aluminum, to active shielding
systems comprised of electromagnetic fields. The concept of active magnetic shielding
is to use high-temperature superconducting coils to induce very high magnetic fields
around the spacecraft. The induced magnetic field will deflect incoming charged
particles (solar particles and galactic cosmic rays), thereby reducing the particle
fluence rate and radiation dose to astronauts behind the shield.
This project developed a model for determining the effectiveness of active
magnetic shielding in reducing radiation dose to astronauts on an interplanetary
mission. This research includes Monte Carlo simulations to determine the
effectiveness of magnetic shielding in decreasing effective dose to astronauts in a
variety of mission scenarios. Dozens of permutations of mission type, mission
duration, solar cycle, shielding configuration, magnetic field, crew sex, crew age, and
phantom type were simulated in GEANT4 to conduct a sensitivity analysis on the effect
of varying each parameter on total crew effective dose for the mission.
Results indicate that magnetic shielding can reduce effective dose to astronauts
on an interplanetary mission to within NASA’s current limits, given a magnetic field of
7 T and/or advanced astronaut age. The detailed results serve to inform the human
spaceflight community on the utility of active magnetic shielding as compared to
passive or no shielding, based upon an end-to-end system model and comparison of
several active magnetic shielding strategies.
Keywords
space radiation, radiation protection, radiation shielding, human spaceflight
Included in
Medicine and Health Sciences Commons, Other Astrophysics and Astronomy Commons, Other Physics Commons