Radiation Transport Models in Space: from Supernovae to Cells
Radiation Transport Models in Space: from Supernovae to Cells
Tony Slaba, NASA Langley Research Center, Hampton VA, USA
Abstract:
Humans embarking on deep space exploration missions will encounter persistent exposure to galactic cosmic rays (GCR) – an energetic and highly complex radiation field that is unlike anything found on Earth. Exposure to such radiation fields can cause various adverse health effects, including cancer, cardiovascular disease, and cognitive impairment and is identified by NASA as one of the five main hazards of human spaceflight. It is therefore critical to be able to fully characterize the exposure received by humans behind shielding in space and project consequent health risks. A wide variety of computational models have been developed over the years to help meet this requirement. In this talk, an overview of the GCR environment in deep space is provided. Methods of propagating GCR fields through the shielding that protects humans in space are described along with simulation tools used to assess biological damage at the cellular scale. Finally, the NASA cancer risk model is briefly described, and risk projections are provided for various mission scenarios. Radiation transport models and solution methods pervade many aspects of this talk. For example, the GCR spectrum impinging on spacecraft is determined by solving the Fokker-Planck transport equation to propagate cosmic rays (believed to originate from supernovae) from the edge of the heliosphere to the vicinity of Earth. The Boltzmann transport equation is solved to transport this GCR spectrum through shielding and human tissue. Monte Carlo methods are used to simulate the transport of low energy electrons that dominate biological damage at the cellular scale. Progress and challenges in each of these areas will be highlighted.
About Tony
Dr. Tony Slaba is a research physicist at NASA Langley Research Center working in the areas of space radiation physics, particle transport, experimental radiobiology, and risk assessment. His early work focused on developing improved space radiation environment and transport models used in engineering design, shield optimization, and operational applications at NASA. He is the primary developer for NASA’s space radiation transport code, HZETRN. Starting in ~2015, Dr. Slaba and colleagues developed new techniques for simulating the space radiation environment at ground-based accelerator facilities for radiobiology experiments (GCR simulation). The GCR simulator at the NASA space radiation laboratory is currently the only facility in the world able to deliver a representative range of particles and energies comprising the space environment in a single experiment. More recently, he has extended NASA’s model for projecting lifetime cancer risk for astronauts to an ensemble framework. The ensemble model considers widely available and equally plausible sub-models of the cancer risk projection, providing a more complete picture of the risk and uncertainty landscape than any single model alone. Dr. Slaba received his PhD in computational and applied mathematics from Old Dominion University in 2007 and has authored or contributed to over 60 peer reviewed journal articles since 2010.
