Lawrence W. Townsend

Estimates of Signicant Post-Carrington Solar Particle Event Radiation Exposures on Mars

1864, 1878, 1894, 1895, and 1896), are made for male and female crew members located at the mean surface elevation and at an altitude of 8 km in the Martian atmosphere. The incident solar particle event proton energy distributions for these events are assumed to be similar to that of the Band function t of the February 1956 event. Radiation exposure estimates were performed using NASA’s On-Line Tool for the Assessment of Radiation in Space (OLTARIS). The HZETRN (High charge (Z) and Energy TRaNsport) space radiation transport code, which is incorporated into OLTARIS, was used to describe the transport of incident protons and any secondary particles generated by their interactions with the atmosphere of Mars, through spacesuit, surface lander, or permanent habitat shielding, and body organ self-shielding. Estimates of eective dose and organ dose are made using the Computerized Anatomical Male (CAM), Computerized Anatomical Female (CAF), Male Adult voXel (MAX), and Female Adult voXel (FAX) human geometry models. The predicted exposures are compared with current NASA Permissible Exposure Limits (PELs).

Analytical Derivation of Abrasion-Ablation Model With Corrections to the First Order Eikonal Expansions

The eikonal expansions in an abrasion-ablation model are derived using Wallace’s perturbation method to account for the Glauber small angle approximations used in previous model. Two correction terms in the first order eikonal expansion were added to the phase factor. The results were compared with results for no correction terms for 20 Ne projectiles incident on 207 Pb targets at 100 MeV/nucleon and 1000 MeV/nucleon energies for , , , , , laboratory angles. The new model will eventually be used to generate improved nuclear cross section databases for space radiation transport codes used in galactic and solar cosmic radiation shielding studies.

Estimates of Carrington-Class Solar Particle Event Radiation Exposures on Mars Behind Polyethylene Shielding

Radiation exposure estimates for crew members on the surface of Mars are made for solar particle event proton radiation environments comparable to the Carrington event of 1859. We assume that the proton energy distribution for this Carrington-type event is similar to that of the Band Function fit of the February 1956 event. In this work we use the BRYNTRN radiation transport code, originally developed at NASA Langley Research Center. The Computerized Anatomical Male and Female human geometry models were utilized to estimate exposures for polyethylene shield areal densities similar to those provided by a spacesuit, a surface lander, and a permanent habitat located at various altitudes in the Mars atmosphere. Comparisons of the predicted organ exposures are made with previously reported values obtained for aluminum shielding and current NASA Permissible Exposure Limits (PELs).