Kerry Lee

Overview of the Martian radiation environment experiment.

Space radiation presents a hazard to astronauts, particularly those journeying outside the protective influence of the geomagnetosphere. Crews on future missions to Mars will be exposed to the harsh radiation environment of deep space during the transit between Earth and Mars. Once on Mars, they will encounter radiation that is only slightly reduced, compared to free space, by the thin Martian atmosphere. NASA is obliged to minimize, where possible, the radiation exposures received by astronauts. Thus, as a precursor to eventual human exploration, it is necessary to measure the Martian radiation environment in detail. The MARIE experiment, aboard the 2001 Mars Odyssey spacecraft, is returning the first data that bear directly on this problem. Here we provide an overview of the experiment, including introductory material on space radiation and radiation dosimetry, a description of the detector, model predictions of the radiation environment at Mars, and preliminary dose-rate data obtained at Mars.

Preparing for the first Medipix detectors in space

Current plans call for two separate missions to deploy Medipix2-Technology-based detectors in space for the first time. NASA is planning to deploy 5 or more Radiation Environment Monitor (REM) units, each of which will contain a Medipix2 TimePix-based detector assembly, on the International Space Station (ISS) during the spring of 2012 as part of a Station Detailed Test Objective (SDTO). These units will be mounted on a single 8-layer printed circuit board containing a USB-based interface. The entire unit will have the form of a typical USB flash-memory device, and the USB interface will provide interactive control and data readout as well as the operating power. Each of the units will be separately plugged into one of the 21 Lenovo® T-61B laptops that are currently onboard the ISS. The purpose of this test is to acquire initial on-orbit data to allow feedback into the design of the next generation of Medipix device, which is intended to support the development of a portable, standalone, wireless and battery-powered personal space radiation dosimeter. The second mission, LUCID (Langton Ultimate Cosmic ray Intensity Detector) is part of a UK outreach project being conducted by the Simon Langton School for Boys in Canterbury, UK. A small instrument containing 5 detector assemblies, also containing the TimePix versions of the Medipix2 technology will be deployed on the upcoming UK TechDemoSat 1 mission, also planned for launch in 2012. These deployments have many similar embedded control software and ground-based analysis software requirements.

FLUKA status and preliminary results from the July-2005 AGS run

As reported in 2005 Aerospace Conference, the FLUKA Monte Carlo code is being modified as part of NASAs Space Radiation Shielding Program for use in simulating the space radiation environment, in order to evaluate the properties of spacecraft and habitat shielding. Since the last workshop, several notable enhancements have been made to the FLUKA code itself and the ancillary support software. These include improvements to the GUI-based packages for analysis of the results as well as GUI-based tools to ease the setup and running of the programs. Examples of these are presented. From the physics perspective, an accelerator run this July at the AGS was undertaken in collaboration with the groups from LBL and MSFC to measure the fragmentation, neutron and secondary charged particle spectra from Fe, Si and C beams at 3, 5 and 10 GeV/A on a variety of targets including C, Al, Fe, Cu and polyethylene. This energy range is the crossover point in event generator technique and the data help guide the evolution of the event generators in this crucial region. Preliminary results from this run is presented for the angular distribution of the secondary charged particles from scattering angles of 3-45 degrees along with normalized comparisons to RQMD and DPMJET, the event generators that are currently employed within FLUKA

Space Applications of the FLUKA Monte‐Carlo Code: Lunar and Planetary Exploration

NASA has recognized the need for making additional heavy‐ion collision measurements at the U.S. Brookhaven National Laboratory in order to support further improvement of several particle physics transport‐code models for space exploration applications. FLUKA has been identified as one of these codes and we will review the nature and status of this investigation as it relates to high‐energy heavy‐ion physics.

Event generators for simulating heavy ion interactions to evaluate the radiation risks in spaceflight

Simulating the space radiation environment with Monte Carlo codes, such as FLUKA, requires the ability to model the interactions of heavy ions as they penetrate spacecraft and crew members bodies. Monte-Carlo-type transport codes use total interaction cross sections to determine when a particular type of interaction has occurred. Then, at that point, a distinct event generator is employed to determine separately the results of that interaction. The space radiation environment contains a full spectrum of radiation types, including relativistic nuclei, which are the most important component for the evaluation of crew doses. Interactions between incident protons with target nuclei in the spacecraft materials and crew members bodies are well understood. However, the situation is substantially less comfortable for incident heavier nuclei (heavy ions). We have been engaged in developing several related heavy ion interaction models based on a quantum molecular dynamics-type approach for energies up through about 5 GeV per nucleon (GeV/A) as part of a NASA consortium that includes a parallel program of cross section measurements to guide and verify this code development

Progress towards a FLUKA based simulation tool aimed at the evaluation of space radiation environments

Goal of the NASA funded FLEUR project is to develop a simulation tool to predict the impact of radiation environments, in particular to evaluate the effect of shielding in space applications. The heart of this tool is the FLUKA Monte Carlo transport code which is traditionally used in related areas of research such as radio‐protection and dosimetry, cosmic ray physics and modeling of biological effects of radiation on DNA (in connection with further external micro codes). An important aspect in this context are heavy ion nuclear interactions which at this point have been implemented in FLUKA for high and medium energies while work is proceeding to cover the low energy range. Further information is available at http://www.fluka.org and http://fleur.cern.ch