Modeling the variations of Dose Rate measured by RAD during the first MSL Martian year: 2012-2014

The Radiation Assessment Detector (RAD), on board Mars Science Laboratory's (MSL) rover Curiosity, measures the {energy spectra} of both energetic charged and neutral particles along with the radiation dose rate at the surface of Mars. With these first-ever measurements on the Martian surface, RAD observed several effects influencing the galactic cosmic ray (GCR) induced surface radiation dose concurrently: [a] short-term diurnal variations of the Martian atmospheric pressure caused by daily thermal tides, [b] long-term seasonal pressure changes in the Martian atmosphere, and [c] the modulation of the primary GCR flux by the heliospheric magnetic field, which correlates with long-term solar activity and the rotation of the Sun. The RAD surface dose measurements, along with the surface pressure data and the solar modulation factor, are analysed and fitted to empirical models which quantitatively demonstrate} how the long-term influences ([b] and [c]) are related to the measured dose rates. {Correspondingly we can estimate dose rate and dose equivalents under different solar modulations and different atmospheric conditions, thus allowing empirical predictions of the Martian surface radiation environment

The Lunar Lander Neutron & Dosimetry (LND) Experiment on Chang’E4

Introduction: Chang'E 4 is the next Chinese mission to the Moon and is planned to land on the far side of the Moon in the South Pole Aitken Basin. The mission consists of a lander, a rover, and a communication relay. Here we describe the Lunar Lander Neutrons & Dosimetry experiment (LND) which will be placed on the lander. It consists of a stack of 10 segmented Si solid-state detectors (SSDs) which forms a particle telescope to measure charged particles (electrons 150-500 keV, protons 12-30 MeV, and heavier nuclei 15-30 MeV/nuc). A special geometrical arrangement allows observations of fast neutrons (and γ-rays) which are also important for dosimetry and cosmic-ray exposure of lunar soils. Thermal neutrons are measured using a very thin Gd conversion foil which is sandwiched between two SSDs. Thermal neutrons are sensitive to subsurface water and important to understand lunar surface mixing processes

The Lunar Lander Neutron & Dosimetry (LND) Experiment on Chang’E4

Chang'E 4 is the next Chinese mission to the Moon and is planned to launch in December 2018 and to land on the far side of the Moon in the South Pole Aitken Basin. The mission consists of a lander, a rover, and a communication relay. Here we describe the Lunar Lander Neutrons & Dosimetry experiment (LND) which will be placed on the lander. It consists of a stack of 10 segmented Si solid-state detectors (SSDs) which forms a particle telescope to measure charged particles (electrons 150-500 keV, protons 12- 30 MeV, and heavier nuclei 15-30 MeV/nuc). A special geometrical arrangement allows observations of fast neutrons (and γ-rays) which are also important for dosimetry and cosmic-ray exposure of lunar soils. Thermal neutrons are measured using a very thin Gd conversion foil which is sandwiched between two SSDs. Thermal neutrons are sensitive to subsurface water and important to understand lunar surface mixing processes

Electron/positron measurements obtained with the Mars Science Laboratory Radiation Assessment Detector on the surface of Mars

The Radiation Assessment Detector (RAD), on board the Mars Science Laboratory (MSL) rover Curiosity, measures the energetic charged and neutral particles and the radiation dose rate on the surface of Mars. Although charged and neutral particle spectra have been investigated in detail, the electron and positron spectra have not been investigated yet. The reason for that is that they are difficult to separate from each other and because of the technical challenges involved in extracting energy spectra from the raw data. We use GEANT4 to model the behavior of the RAD instrument for electron/positron measurements.We compare Planetocosmics predictions for different atmospheric pressures and different modulation parameters 8 with the obtained RAD electron/positron measurements.We find that the RAD electron/positron measurements agree well with the spectra predicted by Planetocosmics. Both RAD measurements and Planetocosmics simulation show a dependence of the electron/ positron fluxes on both atmospheric pressure and solar modulation potential

Energetic Particle Radiation Environment Observed by RAD on the Surface of Mars during the September 2017 Event

The September 10-12 Solar Energetic Particle (SEP) Event produced the strongest increase of the radiation environment measured by the Radiation Assessment Detector (RAD) on the surface of Mars since landing in August 2012. We report the details of the measurements of the energetic particle environment from RAD in Gale crater during this event. The SEP event increased the low-energy proton flux (below 100 MeV) by a factor of thirty, and the higher-energy proton flux by a factor of four, above pre-event levels. The 4He flux (below 100 MeV/nuc) rose by factors up to ten, and neutral particles by a factor of two above background. The increase started on September 10 around 19:50 UTC, peak-level fluxes were reached on the morning of September 11 and prevailed for about 10 hours before decreasing towards background levels. The onset of a Forbush decrease on September 13 decreased the proton flux below pre-event intensities

THE LUNAR LANDER NEUTRON & DOSIMETRY (LND) EXPERIMENT ON CHANG’E4

Chang’E4, the next Chinese mission to the Moon, is planned to launch in December 2018 and to land on the far side of the Moon in the South Pole Aitken Basin. The mission consists of a lander, a rover, and a communication relay around the Earth-Moon L2 libration point. Here we describe the Lunar Lander Neutron Dosimetry experiment (LND) on the lander. [...

Measurements of the neutron spectrum in transit to Mars on the Mars Science Laboratory

The Mars Science Laboratory spacecraft, containing the Curiosity rover, was launched to Mars on 26 November 2011. Although designed for measuring the radiation on the surface of Mars, the Radiation Assessment Detector (RAD) measured the radiation environment inside the spacecraft during most of the 253-day, 560-million-kilometer cruise to Mars. An important factor for determining the biological impact of the radiation environment inside the spacecraft is the specific contribution of neutrons with their high biological effectiveness. We apply an inversion method (based on a maximum-likelihood estimation) to calculate the neutron and gamma spectra from the RAD neutral particle measurements. The measured neutron spectrum (12–436 MeV) translates into a radiation dose rate of 3.8±1.2 μGy/day3.8±1.2 μGy/day and a dose equivalent of 19±5 μSv/day19±5 μSv/day. Extrapolating the measured spectrum (0.1–1000 MeV), we find that the total neutron-induced dose rate is 6±2 μGy/day6±2 μGy/day and the dose equivalent rate is 30±10 μSv/day30±10 μSv/day. For a 360 day round-trip from Earth to Mars with comparable shielding, this translates into a neutron induced dose equivalent of about 11±411±4 mSv

The Lunar Lander Neutron & Dosimetry (LND) Experiment on Chang’E4.

Despite the aim of landing humans on the Moon in the not too distant future, the current knowledge about the radiation environment on the surface of the Moon is based exclusively on calculations using radiation transport models with input parameters from models for the galactic cosmic ray spectra and for solar particle events. Chang'E4 is the next Chinese mission to the Moon and is planned to launch in December 2018 and to land on the far side of the Moon in the South Pole Aitken Basin. The mission consists of a lander, a rover, and a communication relay. Here we describe the Lunar Lander Neutron & Dosimetry experiment (LND) which will be placed on the lander. It consists of a stack of 10 segmented Si solid-state detectors (SSDs) which forms a particle telescope to measure charged particles (electrons 150-500 keV, protons 12-30 MeV, and heavier nuclei 15-30 MeV/nuc). A special geometrical arrangement allows observations of fast neutrons (and -rays) which are also important for dosimetry and cosmic-ray exposure of lunar soils. Thermal neutrons are measured using a very thin Gd conversion foil which is sandwiched between two SSDs. Thermal neutrons are sensitive to subsurface water and important to understand lunar surface mixing processes

The Lunar Lander Neutron & Dosimetry (LND) Experiment on Chang’E4.

Chang'E4, the Chinese mission to the Moon, launched on December 8, 2018 and landed on the far side of the Moon in the von Karman crater on January 3, 2019. The mission consists of a lander, a rover, and a communication relay. In this presentation we will describe first data from the Lunar Lander Neutron & Dosimetry experiment (LND) which is placed on the lander. LND consists of a stack of 10 segmented Si solid-state detectors (SSDs) which forms a particle telescope to measure charged particles (electrons fom 0.5 MeV to several MeV, protons 8-35 MeV, and heavier nuclei 17-75 MeV/nuc). A special geometrical arrangement allows observations of fast neutrons (and - rays) which are also important for dosimetry and cosmic-ray exposure of lunar soils. Thermal neutrons are measured using a very thin Gd conversion foil which is sandwiched between two SSDs. Thermal neutrons are sensitive to subsurface water and important to understand lunar surface mixing processes. [...