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Zeitlin, Cary

Publications and source records attributed to Zeitlin, Cary.

13 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Space radiation measurements during the Artemis I lunar mission

Space radiation is a notable hazard for long-duration human spaceflight. Associated risks include cancer, cataracts, degenerative diseases and tissue reactions from large, acute exposures. Space radiation originates from diverse sources, including galactic cosmic rays, trapped-particle (Van Allen) belts5 and solar-particle events. Previous radiation data are from the International Space Station and the Space Shuttle in low-Earth orbit protected by heavy shielding and Earth’s magnetic field and lightly shielded interplanetary robotic probes such as Mars Science Laboratory and Lunar Reconnaissance Orbiter. Limited data from the Apollo missions and ground measurements with substantial caveats are also available. Here we report radiation measurements from the heavily shielded Orion spacecraft on the uncrewed Artemis I lunar mission. At differing shielding locations inside the vehicle, a fourfold difference in dose rates was observed during proton-belt passes that are similar to large, reference solar-particle events. Interplanetary cosmic-ray dose equivalent rates in Orion were as much as 60% lower than previous observations. Furthermore, a change in orientation of the spacecraft during the proton-belt transit resulted in a reduction of radiation dose rates of around 50%. These measurements validate the Orion for future crewed exploration and inform future human spaceflight mission design.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2017

Particle Radiation Sources, Propagation and Interactions in Deep Space, at Earth, the Moon, Mars, and Beyond: Examples of Radiation Interactions and Effects

Particle radiation has significant effects for astronauts, satellites and planetary bodies throughout the Solar System. Acute space radiation hazards pose risks to human and robotic exploration. This radiation also naturally weathers the exposed surface regolith of the Moon, the two moons of Mars, and other airless bodies, and contributes to chemical evolution of planetary atmospheres at Earth, Mars, Venus, Titan, and Pluto. We provide a select review of recent areas of research covering the origin of SEPs from coronal mass ejections low in the corona, propagation of events through the solar system during the anomalously weak solar cycle 24 and important examples of radiation interactions for Earth, other planets and airless bodies such as the Moon.

Schwadron, Nathan A.↗
NASA NTRS2017

Early Results from the Advanced Radiation Protection Thick GCR Shielding Project

The Advanced Radiation Protection Thick Galactic Cosmic Ray (GCR) Shielding Project leverages experimental and modeling approaches to validate a predicted minimum in the radiation exposure versus shielding depth curve. Preliminary results of space radiation models indicate that a minimum in the dose equivalent versus aluminum shielding thickness may exist in the 20-30 g/cm2 region. For greater shield thickness, dose equivalent increases due to secondary neutron and light particle production. This result goes against the long held belief in the space radiation shielding community that increasing shielding thickness will decrease risk to crew health. A comprehensive modeling effort was undertaken to verify the preliminary modeling results using multiple Monte Carlo and deterministic space radiation transport codes. These results verified the preliminary findings of a minimum and helped drive the design of the experimental component of the project. In first-of-their-kind experiments performed at the NASA Space Radiation Laboratory, neutrons and light ions were measured between large thicknesses of aluminum shielding. Both an upstream and a downstream shield were incorporated into the experiment to represent the radiation environment inside a spacecraft. These measurements are used to validate the Monte Carlo codes and derive uncertainty distributions for exposure estimates behind thick shielding similar to that provided by spacecraft on a Mars mission. Preliminary results for all aspects of the project will be presented.

Norman, Ryan B.↗
NASA NTRS2015

Parallel Study of HEND, RAD, and DAN Instrument Response to Martian Radiation and Surface Conditions

Nuclear detection methods are being used to understand the radiation environment at Mars. JPL (Jet Propulsion Laboratory) assets on Mars include: Orbiter -2001 Mars Odyssey [High Energy Neutron Detector (HEND)]; Mars Science Laboratory Rover -Curiosity [(Radiation Assessment Detector (RAD); Dynamic Albedo Neutron (DAN))]. Spacecraft have instruments able to detect ionizing and non-ionizing radiation. Instrument response on orbit and on the surface of Mars to space weather and local conditions [is discussed] - Data available at NASA-PDS (Planetary Data System).

Mars↗
NASA NTRS2015

Updates from the MSL-RAD Experiment on the Mars Curiosity Rover

The MSL-RAD instrument continues to operate flawlessly on Mars. As of this writing, some 1040 sols (Martian days) of data have been successfully acquired. Several improvements have been made to the instrument's configuration, particularly aimed at enabling the analysis of neutral-particle data. The dose rate since MSL's landing in August 2012 has remained remarkably stable, reflecting the unusual and very weak solar maximum of Cycle 24. Only a few small SEP events have been observed by RAD, which is shielded by the Martian atmosphere. Gale Crater, where Curiosity landed, is 4.4 km below the mean surface of Mars, and the column depth of atmosphere above is approximately 20 g/sq cm, which provides significant attenuation of GCR heavy ions and SEPs. Recent analysis results will be presented, including updated estimates of the neutron contributions to dose and dose equivalent in cruise and on the surface of Mars.

Zeitlin, Cary↗
NASA NTRS2014

Comparison of Martian Surface Radiation Predictions to the Measurements of Mars Science Laboratory Radiation Assessment Detector (MSL/RAD)

For the analysis of radiation risks to astronauts and planning exploratory space missions, detailed knowledge of particle spectra is an important factor. Detailed measurements of the energetic particle radiation environment on the surface of Mars have been made by the Mars Science Laboratory Radiation Assessment Detector (MSL-RAD) on the Curiosity rover since August 2012, and particle fluxes for a wide range of ion species (up to several hundred MeV/u) and high energy neutrons (8 - 1000 MeV) have been available for the first 200 sols. Although the data obtained on the surface of Mars for 200 sols are limited in the narrow energy spectra, the simulation results using the Badhwar-O'Neill galactic cosmic ray (GCR) environment model and the high-charge and energy transport (HZETRN) code are compared to the data. For the nuclear interactions of primary GCR through Mars atmosphere and Curiosity rover, the quantum multiple scattering theory of nuclear fragmentation (QMSFRG) is used, which includes direct knockout, evaporation and nuclear coalescence. Daily atmospheric pressure measurements at Gale Crater by the MSL Rover Environmental Monitoring Station are implemented into transport calculations for describing the daily column depth of atmosphere. Particles impinging on top of the Martian atmosphere reach the RAD after traversing varying depths of atmosphere that depend on the slant angles, and the model accounts for shielding of the RAD by the rest of the instrument. Calculations of stopping particle spectra are in good agreement with the RAD measurements for the first 200 sols by accounting changing heliospheric conditions and atmospheric pressure. Detailed comparisons between model predictions and spectral data of various particle types provide the validation of radiation transport models, and thus increase the accuracy of the predictions of future radiation environments on Mars. These contributions lend support to the understanding of radiation health risks to astronauts for the planning of various mission scenarios.

Kim, Myung-Hee Y.↗
NASA NTRS2014

Comparisons Between Model Predictions and Spectral Measurements of Charged and Neutral Particles on the Martian Surface

Detailed measurements of the energetic particle radiation environment on the surface of Mars have been made by the Radiation Assessment Detector (RAD) on the Curiosity rover since August 2012. RAD is a particle detector that measures the energy spectrum of charged particles (10 to approx. 200 MeV/u) and high energy neutrons (approx 8 to 200 MeV). The data obtained on the surface of Mars for 300 sols are compared to the simulation results using the Badhwar-O'Neill galactic cosmic ray (GCR) environment model and the high-charge and energy transport (HZETRN) code. For the nuclear interactions of primary GCR through Mars atmosphere and Curiosity rover, the quantum multiple scattering theory of nuclear fragmentation (QMSFRG) is used. For describing the daily column depth of atmosphere, daily atmospheric pressure measurements at Gale Crater by the MSL Rover Environmental Monitoring Station (REMS) are implemented into transport calculations. Particle flux at RAD after traversing varying depths of atmosphere depends on the slant angles, and the model accounts for shielding of the RAD "E" dosimetry detector by the rest of the instrument. Detailed comparisons between model predictions and spectral data of various particle types provide the validation of radiation transport models, and suggest that future radiation environments on Mars can be predicted accurately. These contributions lend support to the understanding of radiation health risks to astronauts for the planning of various mission scenarios

Kim, Myung-Hee Y.↗
NASA NTRS2014

Mars' Surface Radiation Environment Measured with the Mars Science Laboratory's Curiosity Rover

The Radiation Assessment Detector (RAD) on the Mars Science Laboratorys Curiosity rover beganmaking detailed measurements of the cosmic ray and energetic particle radiation environmenton the surface of Mars on 7 August 2012. We report and discuss measurements of the absorbeddose and dose equivalent from galactic cosmic rays and solar energetic particles on the martiansurface for 300 days of observations during the current solar maximum. These measurementsprovide insight into the radiation hazards associated with a human mission to the surface of Marsand provide an anchor point with which to model the subsurface radiation environment, withimplications for microbial survival times of any possible extant or past life, as well as for thepreservation of potential organic biosignatures of the ancient martian environment.

radiation environment↗
NASA NTRS2013

Simulation and Comparison of Martian Surface Ionization Radiation

The spectrum of energetic particle radiation and corresponding doses at the surface of Mars is being characterized by the Radiation Assessment Detector (RAD), one of ten science instruments on the Mars Science Laboratory (MSL) Curiosity Rover. The time series of dose rate for the first 300 Sols after landing on Mars on August 6, 2012 is presented here. For the comparison to RAD measurements of dose rate, Martian surface ionization radiation is simulated by utilizing observed space quantities. The GCR primary radiation spectrum is calculated by using the Badhwar-O'Neill 2011 (BO11) galactic cosmic ray (GCR) model, which has been developed by utilizing all balloon and satellite GCR measurements since 1955 and the newer 1997-2012 Advanced Composition Explorer (ACE) measurements. In the BO11 model, solar modulation of the GCR primary radiation spectrum is described in terms of the international smoothed sunspot number and a time delay function. For the transport of the impingent GCR primary radiation through Mars atmosphere, a vertical distribution of atmospheric thickness at each elevation is calculated using the vertical profiles of atmospheric temperature and pressure made by Mars Global Surveyor measurements. At Gale Crater in the southern hemisphere, the seasonal variation of atmospheric thickness is accounted for the daily atmospheric pressure measurements of the MSL Rover Environmental Monitoring Station (REMS) by using low- and high-density models for cool- and warm-season, respectively. The spherically distributed atmospheric distance is traced along the slant path, and the resultant directional shielding by Martian atmosphere is coupled with Curiosity vehicle for dose estimates. We present predictions of dose rate and comparison to the RAD measurements. The simulation agrees to within +/- 20% with the RAD measurements showing clearly the variation of dose rate by heliospheric conditions, and presenting the sensitivity of dose rate by atmospheric pressure, which has been found from the RAD experiments and driven by thermal tides on Martian surface.

Kim, Myung-Hee Y.↗
NASA NTRS2012

MSL-RAD Cruise Operations Concept

The Mars Science Laboratory (MSL) payload includes the Radiation Assessment Detector (RAD) instrument, intended to fully characterize the radiation environment for the MSL mission. The RAD instrument operations concept is intended to reduce impact to spacecraft resources and effort for the MSL operations team. By design, RAD autonomously performs regular science observations without the need for frequent commanding from the Rover Compute Element (RCE). RAD operates with pre-defined "sleep" and "observe" periods, with an adjustable duty cycle for meeting power and data volume constraints during the mission. At the start of a new science observation, RAD performs a pre-observation activity to assess count rates for selected RAD detector elements. Based on this assessment, RAD can enter "solar event" mode, in which instrument parameters (including observation duration) are selected to more effectively characterize the environment. At the end of each observation period, RAD stores a time-tagged, fixed length science data packet in its non-volatile mass memory storage. The operating cadence is defined by adjustable parameters, also stored in non-volatile memory within the instrument. Periodically, the RCE executes an on-board sequence to transfer RAD science data packets from the instrument mass storage to the MSL downlink buffer. Infrequently, the RAD instrument operating configuration is modified by updating internal parameter tables and configuration entries.

Mars Science Laboratory (MSL)↗
NASA NTRS2006

Isotopic Dependence of GCR Fluence behind Shielding

In this paper we consider the effects of the isotopic composition of the primary galactic cosmic rays (GCR), nuclear fragmentation cross-sections, and isotopic-grid on the solution to transport models used for shielding studies. Satellite measurements are used to describe the isotopic composition of the GCR. For the nuclear interaction data-base and transport solution, we use the quantum multiple-scattering theory of nuclear fragmentation (QMSFRG) and high-charge and energy (HZETRN) transport code, respectively. The QMSFRG model is shown to accurately describe existing fragmentation data including proper description of the odd-even effects as function of the iso-spin dependence on the projectile nucleus. The principle finding of this study is that large errors (+/-100%) will occur in the mass-fluence spectra when comparing transport models that use a complete isotopic-grid (approx.170 ions) to ones that use a reduced isotopic-grid, for example the 59 ion-grid used in the HZETRN code in the past, however less significant errors (<+/-20%) occur in the elemental-fluence spectra. Because a complete isotopic-grid is readily handled on small computer workstations and is needed for several applications studying GCR propagation and scattering, it is recommended that they be used for future GCR studies.

Cucinotta, Francis A.↗
NASA NTRS2002

Spatial distribution and yield of DNA double-strand breaks induced by 3-7 MeV helium ions in human fibroblasts

Accelerated helium ions with mean energies at the target location of 3-7 MeV were used to simulate alpha-particle radiation from radon daughters. The experimental setup and calibration procedure allowed determination of the helium-ion energy distribution and dose in the nuclei of irradiated cells. Using this system, the induction of DNA double-strand breaks and their spatial distributions along DNA were studied in irradiated human fibroblasts. It was found that the apparent number of double-strand breaks as measured by a standard pulsed-field gel assay (FAR assay) decreased with increasing LET in the range 67-120 keV/microm (corresponding to the energy of 7-3 MeV). On the other hand, the generation of small and intermediate-size DNA fragments (0.1-100 kbp) increased with LET, indicating an increased intratrack long-range clustering of breaks. The fragment size distribution was measured in several size classes down to the smallest class of 0.1-2 kbp. When the clustering was taken into account, the actual number of DNA double-strand breaks (separated by at least 0.1 kbp) could be calculated and was found to be in the range 0.010-0.012 breaks/Mbp Gy(-1). This is two- to threefold higher than the apparent yield obtained by the FAR assay. The measured yield of double-strand breaks as a function of LET is compared with theoretical Monte Carlo calculations that simulate the track structure of energy depositions from helium ions as they interact with the 30-nm chromatin fiber. When the calculation is performed to include fragments larger than 0.1 kbp (to correspond to the experimental measurements), there is good agreement between experiment and theory.

NASA Program Biomedical Research and Countermeasur↗