Modelling Extraterrestrial Radiation Environments for

• Main Author: David Fallaize
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2007
• Subjects: Antarctic; Antarc*
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.111.8245; http://www.ucl.ac.uk/~ucbpdrf/files/mars.pdf

This project is concerned with estimating the probability of bacteria being able to survive beneath the surface of Mars, given the harsh environmental conditions which exist there. To make such an estimate at least two things must be known: the level of ionizing radiation at the surface of Mars due to both solar and galactic radiation; and the capacity of biological material to survive the radiation. Correspondingly this project is divided into two parts: firstly the simulation of the radiation environment on Mars, using a Monte-Carlo simulation program based upon the Geant4 physics framework; secondly a set of biological experiments which aim to link the damage caused by desiccation to the damage caused by γ radiation, using Antarctic extremophile bacteria as proxies for hypothetical Martian bacteria. The result of the first part of the project is a Linear Energy Transfer (LET) spectrum for the surface of Mars corresponding to a year of SEP radiation, and a partial GCR spectrum up to 500 GeV protons and 40 GeV Helium nuclei. The LET spectrum is a biologically-relevant measurement of the radiation environment on Mars where “high LET ” radiation (such as α particles) is biologically very damaging in comparison to “low LET ” radiation (such as γ rays). These results show that the shape of the LET spectrum is not determined by the energy of primary radiation particles, but by the chemical composition