Presentation by Alumnus Arturo Ortiz at ICES
Arturo Ortiz, SpSt M.Sc. 2015, presented a technical paper at the 45th International Conference on Environmental Systems (ICES), held at Seattle on July 12-16, 2015. The paper was based on Ortiz’s M.Sc. thesis, and was coauthored with UND Associate Professors Vadim Rygalov and Pablo de León. Dr. Rygalov was the thesis advisor.
Ortiz, A. R., Rygalov, V. Y., and de León, P. (2015), “Radiation Protection Strategy Development for Mars Surface Exploration,” 45th International Conference on Environmental Systems (ICES), 12-16 July 2015, Paper ICES-2015-54
Abstract: Computational analyses were performed to assess space radiation shielding effectiveness of ‘minimal’ planetary surface exploration concepts developed by the University of North Dakota: the Inflatable Lunar-Martian Habitat (ILMH), Pressurized Electric Rover (PER), and NDX-2 space suit. Using the HZETRN and NUCFRG3 radiation analysis computer codes with ray-by-ray transport through three-dimensional shielding thickness distributions, the authors calculated doses in the Mars surface environment under conditions of the February 1956 solar flare and 1977 solar minimum galactic cosmic radiation. Results indicate that polyethylene shielding of 5, 10, and 15 g/cm2 can protect the ILMH up to 11, 18, and 25 km surface elevation, respectively, while 1m of Mars regolith can protect up to 30 km. The shielded ILMH is adequate as primary radiation storm shelter, and meets permissible limits for 30 and 365 day exposures. The structural shell of the PER can protect from acute exposure only up to 5 km elevation, and hence is not adequate as a secondary storm shelter. A Mylar space suit at a thickness of 500 micrometers can protect from acute exposure only up to 4 km. The authors estimated doses for surface stays of 365 days, and found total dose varied from 176 mGy-Eq while performing minimal exploration, to 1025 mGy-Eq in a scenario that includes extravehicular activity (EVA) between 24 and 30 km elevation during a large solar flare. Acute exposure during the flare at high surface elevation approaches the threshold for acute radiation syndrome. Since the PER and space suit cannot protect from short term exposure except over a limited elevation range, fast access to a shielded habitat will always be required if a major solar storm occurs during surface roving or EVA. This drives a need to implement an early warning system for solar storms to enable safe extended surface exploration of Mars.