Observatories of the Solar Corona and Active Regions (OSCAR)

Coronal Mass Ejections (CMEs) and Corotating Interaction Regions (CIRs) are major sources of magnetic storms on Earth and are therefore considered to be the most dangerous space weather events. The Observatories of Solar Corona and Active Regions (OSCAR) mission is designed to identify the 3D structure of coronal loops and to study the trigger mechanisms of CMEs in solar Active Regions (ARs) as well as their evolution and propagation processes in the inner heliosphere. It also aims to provide monitoring and forecasting of geo- effective CMEs and CIRs. OSCAR would contribute to significant advancements in the field of solar physics, improvements of the current CME prediction models, and provide data for reliable space weather forecasting. These objectives are achieved by utilising two spacecraft with identical instrumentation, located at a heliocentric orbital distance of 1 AU from the Sun. The spacecraft will be separated by an angle of 68° to provide optimum stereoscopic view of the solar corona. We study the feasibility of such a mission and propose a preliminary design for OSCAR

Erratum: A space weather mission concept: Observatories of the solar corona and active regions (oscar) (Journal of Space Weather and Space Climate (2015) 5 (A4) DOI: 10.1051/swsc/2015003)

In this erratum we acknowledge EASCO as one of the inspirational mission concepts that helped the development of our original mission concept OSCAR

Study and test of micro-channel plates used in the dual ion spectrometer of the MMS mission by NASA

The Magnetospheric Multiscale mission led by NASA has been designed to study the micro-physics of Magnetic Reconnection in Earth's magnetosphere by using four identical spacecrafts with instruments with high temporal and spatial resolutions. Among these instruments are the Dual Ion Spectrometers (DIS) engineered to measure the 3D distribution of ion flux in space. The detector assembly of the DIS consists of Micro-Channel Plates (MCP) mounted in Chevron configuration. Centre d'Etude Spatiale des Rayonnements (CESR), Toulouse is responsible for the provision and testing of all fifty MCP pairs for this mission. The goal of the work was to participate in the testing and characterization of the first prototype of the MCPs. It was achieved by understanding the working and characteristics of the MCPs in general and getting familiar with the detector assembly of the DIS i.e. the MCP pair and the detector circuit board in particular. To perform the testing, it was necessary to understand the testing system as well. These topics are described in this report along with the testing procedure and the data analysis. The testing procedure was developed eventually after facing several problems during the testing. MCP pair characteristics like pulse height distributions, gain, resistance and the MCP operating voltages for the mission were determined on analyzing the data. Crosstalk was found in the circuit board of the detector assembly and has also been discussed.Validerat; 20101217 (root

Galactic Cosmic Ray Exposure of Humans in Space - Influence of galactic cosmic ray models and shielding on dose calculations for low-Earth orbit and near-Earth interplanetary space

The radiation environment in space is one of the primary concerns for human spaceflight as it poses potential risk to astronauts’ health. Galactic Cosmic Rays (GCR), consisting of high-energy nuclei, are a major source of radiation exposure in space. As the number of people visiting space in low-Earth orbit is increasing and mankind prepares to go beyond, the issue of radiation protection against GCR thus becomes vitally important. The pre-flight assessment of radiation-related health risks is achieved by performing numerical simulations of the mission scenario to estimate the necessary radiation-dose quantities. This technique requires models describing the radiation spectra, the target and shield configurations, and additionally transport codes to simulate the passage of radiation through matter. The reliability of the calculated dose therefore depends on the accuracy of all these models. During the course of this PhD work, commonly used models describing the GCR spectra are evaluated for their accuracy for various time periods. The model spectra of nuclei, most relevant for space dosimetry, are compared with measurements from high-altitude balloon flights and space missions. The GCR models included in this work are CREME96, CREME2009, Burger-Usoskin, Badhwar-O’Neill2010, Badhwar-O’Neill2011, Matthiä-ACE/OULU and SPENVIS/ISO15390. The influence of using these different GCR models on the dose calculations is studied for a time period ranging over the last four decades. This is achieved by calculating the absorbed dose and dose equivalent rates in a spherical water phantom using the GEANT4 Monte-Carlo framework. Additionally, the influence of aluminium shielding of varying thicknesses (0.3 g/cm², 10 g/cm² and 40 g/cm²) on the dose is investigated for a time period ranging from 1997 to 2012. All these investigations are performed for near-Earth interplanetary space and the orbit of the International Space Station (ISS). Apart from examining these parameters the effective dose, being the baseline quantity for radiation-risk assessment, is estimated. The quantity is calculated for the end of the year 2009 when the highest GCR intensity since the dawn of human spaceflight era was observed. Further studies presented in the thesis include the relative contribution of particles with different energies to the total exposure and the comparison of calculated dose with the measurements conducted inside the ISS and in-transit to Mars by the MSL/RAD instrument

Estimation of Galactic Cosmic Ray exposure inside and outside the Earth’s magnetosphere during the recent solar minimum between solar cycles 23 and 24

The evidently low solar activity observed between solar cycles 23 and 24 during the years 2008–2010 led to a substantial increase in the Galactic Cosmic Ray (GCR) intensity in comparison with preceding solar minima. As the GCRs consist of highly-ionizing charged particles having the potential to cause biological damage, they are a subject of concern for manned missions to space. With the enhanced particle fluxes observed between 2008 and 2010, it is reasonable to assume that the radiation exposure from GCR must have also increased to unusually high levels. In this paper, the GCR exposure outside and inside the Earth’s magnetosphere is numerically calculated for time periods starting from 1970 to the end of 2011 in order to investigate the increase in dose levels during the years 2008–2010 in comparison with the last three solar minima. The dose rates were calculated in a water sphere, used as a surrogate for the human body, either unshielded or surrounded by aluminium shielding of 0.3, 10 or 40 g/cm². By performing such a long-term analysis, it was estimated that the GCR exposure during the recent solar minimum was indeed the largest in comparison with previous minima and that the increase was more pronounced for locations outside the magnetosphere

Assessment of Galactic Cosmic Ray models

Among several factors involved in the development of a manned space mission concept, the astronauts' health is a major concern that needs to be considered carefully. Galactic Cosmic Rays (GCRs), which mainly consist of high-energetic nuclei ranging from hydrogen to iron and beyond, pose a major radiation health risk in long-term space missions. It is therefore required to assess the radiation exposure of astronauts in order to estimate their radiation risks. This can be done either by performing direct measurements or by making computer based simulations from which the dose can be derived. A necessary prerequisite for an accurate estimation of the exposure using simulations is a reliable description of the GCR spectra. The aim of this work is to compare GCR models and to test their applicability for the exposure assessment of astronauts. To achieve this, commonly used models capable of describing both light and heavy GCR particle spectra were evaluated by investigating the model spectra for various particles over several decades. The updated Badhwar-O'Neill model published in the year 2010, CREME2009 which uses the International Standard model for GCR, CREME96 and the Burger-Usoskin model were examined. Hydrogen, helium, oxygen and iron nuclei spectra calculated by the different models are compared with measurements from various high-altitude balloon and space-borne experiments. During certain epochs in the last decade, there are large discrepancies between the GCR energy spectra described by the models and the measurements. All the models exhibit weaknesses in describing the increased GCR flux that was observed in 2009-201

A Space Weather mission concept: Observatories of the Solar Corona and Active Regions (OSCAR)

Coronal Mass Ejections (CMEs) and Corotating Interaction Regions (CIRs) are major sources of magnetic storms on Earth and are therefore considered to be the most dangerous space weather events. The Observatories of Solar Corona and Active Regions (OSCAR) mission is designed to identify the 3D structure of coronal loops and to study the trigger mechanisms of CMEs in solar Active Regions (ARs) as well as their evolution and propagation processes in the inner heliosphere. It also aims to provide monitoring and forecasting of geo-effective CMEs and CIRs. OSCAR would contribute to significant advancements in the field of solar physics, improvements of the current CME prediction models, and provide data for reliable space weather forecasting. These objectives are achieved by utilising two spacecraft with identical instrumentation, located at a heliocentric orbital distance of 1 AU from the Sun. The spacecraft will be separated by an angle of 68° to provide optimum stereoscopic view of the solar corona. We study the feasibility of such a mission and propose a preliminary design for OSCAR

A space weather mission concept: observatories of the solar corona and active regions (oscar) – Erratum

In this erratum we acknowledge EASCO as one of the inspirational mission concepts that helped the development of our original mission concept OSCAR