scholarly journals Radiation environment for future human exploration on the surface of Mars: the current understanding based on MSL/RAD dose measurements

2021 ◽  
Vol 29 (1) ◽  
Author(s):  
Jingnan Guo ◽  
Cary Zeitlin ◽  
Robert F. Wimmer-Schweingruber ◽  
Donald M. Hassler ◽  
Bent Ehresmann ◽  
...  
Keyword(s):  
Radiation Field ◽  
Energetic Particle ◽  
Solar Maximum ◽  
Cosmic Ray ◽  
Radiation Environment ◽  
Dose Equivalent ◽  
Particle Radiation ◽  
Return Trip ◽  
Human Exploration

AbstractPotential deleterious health effects to astronauts induced by space radiation is one of the most important long-term risks for human space missions, especially future planetary missions to Mars which require a return-trip duration of about 3 years with current propulsion technology. In preparation for future human exploration, the Radiation Assessment Detector (RAD) was designed to detect and analyze the most biologically hazardous energetic particle radiation on the Martian surface as part of the Mars Science Laboratory (MSL) mission. RAD has measured the deep space radiation field within the spacecraft during the cruise to Mars and the cosmic ray induced energetic particle radiation on Mars since Curiosity’s landing in August 2012. These first-ever surface radiation data have been continuously providing a unique and direct assessment of the radiation environment on Mars. We analyze the temporal variation of the Galactic Cosmic Ray (GCR) radiation and the observed Solar Energetic Particle (SEP) events measured by RAD from the launch of MSL until December 2020, i.e., from the pre-maximum of solar cycle 24 throughout its solar minimum until the initial year of Cycle 25. Over the long term, the Mars’s surface GCR radiation increased by about 50% due to the declining solar activity and the weakening heliospheric magnetic field. At different time scales in a shorter term, RAD also detected dynamic variations in the radiation field on Mars. We present and quantify the temporal changes of the radiation field which are mainly caused by: (a) heliospheric influences which include both temporary impacts by solar transients and the long-term solar cycle evolution, (b) atmospheric changes which include the Martian daily thermal tide and seasonal CO$$_2$$ 2 cycle as well as the altitude change of the rover, (c) topographical changes along the rover path-way causing addition structural shielding and finally (d) solar particle events which occur sporadically and may significantly enhance the radiation within a short time period. Quantification of the variation allows the estimation of the accumulated radiation for a return trip to the surface of Mars under various conditions. The accumulated GCR dose equivalent, via a Hohmann transfer, is about $$0.65 \pm 0.24$$ 0.65 ± 0.24 sievert and $$1.59 \pm 0.12$$ 1.59 ± 0.12 sievert during solar maximum and minimum periods, respectively. The shielding of the GCR radiation by heliospheric magnetic fields during solar maximum periods is rather efficient in reducing the total GCR-induced radiation for a Mars mission, by more than 50%. However, further contributions by SEPs must also be taken into account. In the future, with advanced nuclear thrusters via a fast transfer, we estimate that the total GCR dose equivalent can be reduced to about 0.2 sievert and 0.5 sievert during solar maximum and minimum periods respectively. In addition, we also examined factors which may further reduce the radiation dose in space and on Mars and discuss the many uncertainties in the interpreting the biological effect based on the current measurement.

The Radiation Environment on the Surface of Mars: dMEREM predictions based on RAD data

2021 ◽  
Author(s):  
Patrícia Gonçalves ◽  
Luisa Arruda ◽  
Marco Pinto
Keyword(s):  
Radiation Field ◽  
Solar Energetic Particle ◽  
Cosmic Ray ◽  
High Energy ◽  
Galactic Cosmic Rays ◽  
Field Of View ◽  
Radiation Environment ◽  
Soil Composition ◽  
Particle Radiation ◽  
Spectrometer Data

<p>The characterisation of the Martian radiation environment is essential to understand if the planet can sustain life and ultimately if its human exploration is feasible. The major components of the radiation environment in the Mars orbit, are Galactic Cosmic Rays (GCRs) and Solar Energetic Particle (SEP) events. Since Mars has a negligible magnetic field and a much thinner atmosphere compared to the Earth’s, its surface is exposed to GCR and eventual SEP events, as well as to secondary particles produced in the atmosphere and in the shallow layers of the planet. The Curiosity rover that has been exploring the surface of Mars since August 2012, carries in its Mars Science Laboratory (MSL), the Radiation Assessment Detector (RAD) which measures high-energy radiation, such as protons, energetic ions of various elements, neutrons, and gamma rays. That includes not only direct radiation from space, but also secondary radiation produced by the interaction of space radiation with the atmosphere and surface rocks and soil.</p> <p><br />The detailed Martian Energetic Radiation Environment Model (dMEREM) is a GEometry ANd Tracking (GEANT4) based model developed for ESA which enables to predict the radiation environment expected at different locations on the Martian orbit, atmosphere and surface, as a function of epoch, latitude and longitude, taking into account the specific atmospheric and soil composition. dMEREM can be interfaced to different Primary Particle Models, such as the ISO-15390 and the Badhwar - O'Neill (BON) 2014 or 2020 Galactic Cosmic Ray Flux Models, or the National Aeronautics and Space Administration (NASA) Emission of Solar Protons (ESP) model for solar energetic proton fluences. dMEREM is interfaced with the European Mars Climate Database from where it retrieves information on the atmosphere composition and density at specific locations and solar longitudes and Gamma Ray Spectrometer data aboard Mars Odyssey, for the description of Mars soil composition, although soil compositions for specific locations, including those locally sampled by Martian rovers can also be defined by the user. dMEREM provides the kinetic energy and directional spectra of all particle types produced in the interactions of energetic particles with the Martian Atmosphere and Soil.</p> <p>The dMEREM validation results using differential proton fluxes stopping in the RAD sensor head as measured by MSL/RAD in Gale crater from November 15, 2015 to January 15, 2016 and in the begin of September 2017 is presented. Although the RAD only measures a limited field-of-view in zenith angle of the Martian Particle Radiation Field, the good agreement between the RAD data and the dMEREM predictions for protons within the RAD field of-view, are used as the basis for the use of dMEREM in the assessment of the expected ionizing radiation field on the surface of Mars for particles coming from all directions, including albedo particles. This assessment is also used to make predictions of dosimetric quantities, such as Ambient Dose Equivalent and Effective Dose, relevant for Human Space Flight, for the considered data periods.  </p>

scholarly journals The effects of the big storm events in the first half of 2015 on the radiation belts observed by EPT/PROBA-V

2016 ◽  
Vol 34 (1) ◽  
pp. 75-84 ◽  
Author(s):  
V. Pierrard ◽  
G. Lopez Rosson
Keyword(s):  
Charged Particle ◽  
High Resolution ◽  
Geomagnetic Storm ◽  
Energetic Particle ◽  
High Energy ◽  
Radiation Belts ◽  
Radiation Environment ◽  
Storm Event ◽  
Storm Events ◽  
Particle Radiation

Abstract. With the energetic particle telescope (EPT) performing with direct electron and proton discrimination on board the ESA satellite PROBA-V, we analyze the high-resolution measurements of the charged particle radiation environment at an altitude of 820 km for the year 2015. On 17 March 2015, a big geomagnetic storm event injected unusual fluxes up to low radial distances in the radiation belts. EPT electron measurements show a deep dropout at L > 4 starting during the main phase of the storm, associated to the penetration of high energy fluxes at L < 2 completely filling the slot region. After 10 days, the formation of a new slot around L = 2.8 for electrons of 500–600 keV separates the outer belt from the belt extending at other longitudes than the South Atlantic Anomaly. Two other major events appeared in January and June 2015, again with injections of electrons in the inner belt, contrary to what was observed in 2013 and 2014. These observations open many perspectives to better understand the source and loss mechanisms, and particularly concerning the formation of three belts.

Energetic Particle Environment near the Sun from Parker Solar Probe

2020 ◽  
Author(s):  
Nathan Schwadron ◽  
Keyword(s):  
Energetic Particle ◽  
Energetic Particles ◽  
Solar Energetic Particles ◽  
Radiation Environment ◽  
The Sun ◽  
Particle Radiation ◽  
Integrated Science ◽  
Direct Observations ◽  
Interaction Regions ◽  
Inner Heliosphere

&lt;p&gt;NASA&amp;#8217;s Parker Solar Probe (PSP) mission recently plunged through the inner heliosphere to perihelia at ~24 million km (~35 solar radii), much closer to the Sun than any prior human made object. Onboard PSP, the Integrated Science Investigation of the Sun (IS&amp;#664;IS) instrument suite made groundbreaking measurements of solar energetic particles (SEPs). Here we discuss the near-Sun energetic particle radiation environment over PSP&amp;#8217;s first two orbits, which reveal where and how energetic particles are energized and transported. We find a great variety of energetic particle events accelerated both locally and remotely. These include co-rotating interaction regions (CIRs), &amp;#8220;impulsive&amp;#8221; SEP events driven by acceleration near the Sun, and events related to Coronal Mass Ejections (CMEs). These IS&amp;#664;IS observations made so close to the Sun provide critical information for investigating the near-Sun transport and energization of solar energetic particles that was difficult to resolve from prior observations. We discuss the physics of particle acceleration and transport in the context of various theories and models that have been developed over the past decades. This study marks a major milestone with humanity&amp;#8217;s reconnaissance of the near-Sun environment and provides the first direct observations of the energetic particle radiation environment in the region just above the corona.&lt;/p&gt;

scholarly journals Energetic Particle Radiation Environment Observed by RAD on the Surface of Mars During the September 2017 Event

2018 ◽  
Vol 45 (11) ◽  
pp. 5305-5311 ◽  
Author(s):  
B. Ehresmann ◽  
D. M. Hassler ◽  
C. Zeitlin ◽  
J. Guo ◽  
R. F. Wimmer‐Schweingruber ◽  
...  
Keyword(s):  
Energetic Particle ◽  
Radiation Environment ◽  
Particle Radiation

Characterizing the Dynamics of CME-Driven Coronal Bright Fronts Using The SPREAdFAST Framework 

2021 ◽  
Author(s):  
Mohamed Nedal ◽  
Kamen Kozarev ◽  
Rositsa Miteva
Keyword(s):  
Energetic Particle ◽  
Large Scale ◽  
Numerical Models ◽  
Solar Energetic Particle ◽  
Time Dependent ◽  
Radiation Environment ◽  
Source Surface ◽  
The Sun ◽  
Particle Radiation ◽  
Field Source

&lt;p&gt;In this work, we present a full characterization of over 50 historical Coronal Mass Ejection (CME)-driven compressive waves in the low solar corona, related to solar energetic particle events near Earth, using the Solar Particle Radiation Environment Analysis and Forecasting - Acceleration and Scattering Transport (SPREAdFAST) framework. SPREAdFAST is a physics-based, operational heliospheric solar energetic particle (SEP) forecasting system, which incorporates a chain of data-driven analytic and numerical models for estimating: a) coronal magnetic field from Potential Field Source Surface (PFSS) and Magnetohydrodynamics (MHD); b) dynamics of large-scale coronal (CME-driven) shock waves; c) energetic particle acceleration; d) scatter-based, time-dependent SEP propagation in the heliosphere to specific time-dependent positions. SPREAdFAST allows for producing predictions of SEP fluxes at multiple locations in the inner heliosphere, by modeling their acceleration at CMEs near the Sun, and their subsequent interplanetary transport. We used sequences of base-difference images obtained from the AIA instrument on board the SDO satellite, with 24-second cadence. We calculated time-dependent speeds in both the radial and lateral (parallel to the solar limb) directions, mean intensities and thicknesses of the fronts, and major and minor axes. This is essential for characterizing the SEP spectra near the Sun. The kinematics measurements were used to generate time-dependent 3D geometric models of the wave fronts and time-dependent plasma diagnostics using MHD and DEM model results.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

scholarly journals Galactic Cosmic Ray induced absorbed dose rate in deep space – Accounting for detector size, shape, material, as well as for the solar modulation

2019 ◽  
Vol 9 ◽  
pp. A14 ◽  
Author(s):  
Saša Banjac ◽  
Lars Berger ◽  
Sönke Burmeister ◽  
Jingnan Guo ◽  
Bernd Heber ◽  
...  
Keyword(s):  
Energy Range ◽  
Dose Rate ◽  
Radiation Field ◽  
Absorbed Dose ◽  
Cosmic Ray ◽  
Radiation Environment ◽  
Solar Modulation ◽  
Deep Space ◽  
Absorbed Dose Rate ◽  
Galactic Cosmic Ray

Depending on the radiation field, the absorbed dose rate can depend significantly upon the size of the detectors or the phantom used in the models. In deep space (interplanetary medium) the radiation field is on avarage dominated by Galactic Cosmic Ray (GCR) nuclei. Here, the deep space dose rate that a typical small silicon slab detector measures is compared to a larger phantom corresponding to an ICRU sphere with a 15 cm radius composed of water. To separate and understand respective effects from the composition, size and shape differences in the detectors, this comparison is implemented in several steps. For each phantom, the absorbed dose rate due to GCR nuclei up to Z = 28, as a function of solar modulation conditions, is calculated. The main components of the GCR flux are protons, followed by helium nuclei and electrons, with Z > 2 nuclei accounting for approximately 1% of the total number of particles. Among the light nuclei with Z > 2, most abundant ones are C, N and O. In this study, we use the GEANT4 model to calculate the absorbed dose (energy deposited as ionization, divided by mass) due to the GCR flux provided by the Badhwar-O’Neill 2010 (BON-10) model. Furthermore, we investigate how the determined absorbed dose rate changes throughout the solar cycle by varying the GCR models from solar minimum to solar maximum conditions. The developed model is validated against the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) microdosimeter measurements. In our current approach, we do not consider the effects of shielding, which will always be present under realistic scenarios. A second goal of this study is to quantify the contribution of each Z = 1, …, 28 GCR nuclei to absorbed dose rate, in relation to the phantom characteristics. For each Z we determine the most relevant energy range in the GCR spectra for absorbed dose rate estimations. Furthermore, we calculate a solar modulation dependent conversion factor to convert absorbed dose rate measured in silicon to absorbed dose rate in water. This information will improve our understanding of the radiation environment due to GCR in the near-Earth deep space and also benefit further modeling efforts by limiting the number and energy range of primary particle species that have to be considered.

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