NASA's first ground-based Galactic Cosmic Ray Simulator: Enabling a new era in space radiobiology research

• Published in: PLoS biology 2020-05, Vol.18 (5), p.e3000669
• Main Authors: Simonsen, Lisa C, Slaba, Tony C, Guida, Peter, Rusek, Adam
• Format: Article
• Language: English
• Subjects: Aerospace environments; Animal models; Astronauts; BASIC BIOLOGICAL SCIENCES; Beam switching; Biology and Life Sciences; Cancer; Carcinogenesis; Carcinogens; Cardiovascular diseases; Central nervous system; Chemical elements; Cognitive ability; Coronary artery disease; Cosmic radiation; Cosmic rays; Degradation; Design; Design and construction; Dosimeters; Dosimetry; Earth magnetosphere; Energy; Exposure; Galactic cosmic rays; Health risk assessment; Health risks; Heart diseases; Helium; Helium ions; Housing; Immune system; Ion beams; Ions; Laboratories; Lunar exploration; Lunar surface vehicles; Mars; Mars missions; Methods and Resources; Mitigation; Moon; Neurological complications; Neurological diseases; Optimization; Particle beams; Physical Sciences; Polyethylene; Polyethylenes; Protons; Radiation effects; Radiobiology; Research and Analysis Methods; Simulation; Solar system; Space missions; Space simulators; Technology; Testing; X-rays
• ISSN: 1545-7885; 1544-9173; 1545-7885
• DOI: 10.1371/journal.pbio.3000669

With exciting new NASA plans for a sustainable return to the moon, astronauts will once again leave Earth's protective magnetosphere only to endure higher levels of radiation from galactic cosmic radiation (GCR) and the possibility of a large solar particle event (SPE). Gateway, lunar landers, and surface habitats will be designed to protect crew against SPEs with vehicle optimization, storm shelter concepts, and/or active dosimetry; however, the ever penetrating GCR will continue to pose the most significant health risks especially as lunar missions increase in duration and as NASA sets its aspirations on Mars. The primary risks of concern include carcinogenesis, central nervous system (CNS) effects resulting in potential in-mission cognitive or behavioral impairment and/or late neurological disorders, degenerative tissue effects including circulatory and heart disease, as well as potential immune system decrements impacting multiple aspects of crew health. Characterization and mitigation of these risks requires a significant reduction in the large biological uncertainties of chronic (low-dose rate) heavy-ion exposures and the validation of countermeasures in a relevant space environment. Historically, most research on understanding space radiation-induced health risks has been performed using acute exposures of monoenergetic single-ion beams. However, the space radiation environment consists of a wide variety of ion species over a broad energy range. Using the fast beam switching and controls systems technology recently developed at the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory, a new era in radiobiological research is possible. NASA has developed the "GCR Simulator" to generate a spectrum of ion beams that approximates the primary and secondary GCR field experienced at human organ locations within a deep-space vehicle. The majority of the dose is delivered from protons (approximately 65%-75%) and helium ions (approximately 10%-20%) with heavier ions (Z ≥ 3) contributing the remainder. The GCR simulator exposes state-of-the art cellular and animal model systems to 33 sequential beams including 4 proton energies plus degrader, 4 helium energies plus degrader, and the 5 heavy ions of C, O, Si, Ti, and Fe. A polyethylene degrader system is used with the 100 MeV/n H and He beams to provide a nearly continuous distribution of low-energy particles. A 500 mGy exposure, delivering doses from each of the 33 beams, requires approxima