The FAA, using its CARI-6 program, provides galactic cosmic radiation dosage rates for any location on the Earth from ground up to 60,000 ft (≈18,300 m). One way to protect astronauts from galactic cosmic radiation (GCR) on a Mars mission is to use material shielding. However, current radiation shielding code does not model shields thicker than about 100 to 200 gm/cm2, and it has been shown that this shield thickness is insufficient to provide protection for a trip to Mars. There is effort underway to extend the code to thicker shields, but there is a lack of experimental data to use to verify the code. The atmosphere represents a very thick and effective radiation shield, and that atmospheric radiation data might be used as a source of verification data.
CARI-6 measured data represents the total radiation reaching that point from all directions through the atmosphere, ranging from relatively small amounts of air directly upward to large amounts near the horizon. A new algorithm shows how to take this information, which represents the total radiation reaching a location through a wide variety of atmospheric thicknesses, and obtain the radiation shielding function for the atmosphere. This information is important to NASA as it tries to estimate how much material might be needed to protect an astronaut on a round trip to Mars.
The fidelity of the solution was increased by attempting to solve the problem in discrete form. Mathematica 8.0 was used to process the developed algorithm. There are primarily two innovations: (1) simply understanding and setting up the problem in mathematical form, and (2) developing a discrete algorithm that decomposes the integral problem into a form where Mathematica 8.0 algorithms could be applied to solve it.
The integral that results in this analysis is highly nonlinear, yet an algorithm was developed that allows it to be put in linear form such that the integral can be replaced with a matrix equation. The resulting form is now amenable to standard optimization algorithms, several of which are available within Mathematica. This algorithm is probably the most novel feature of the problem solution.
This work was done by Robert Youngquist, Mark Nurge, and Stanley Starr of Kennedy Space Center; and Steven Koontz of Johnson Space Center. For more information, contact the Kennedy Space Center Technology Transfer Office at 321-867-7171. KSC-13763