Cherenkov detectors have been used in space for decades to measure Galactic Cosmic Rays (GCRs), Solar Energetic Particles (SEPs) and trapped particles. We present proof-of-concept GRAS/Geant4 simulations to both show that a cubic fused silica Cherenkov detector with SiPM in LEO has a good sensitivity to SEP and GCR protons as a function of cut-off rigidity and trapped protons in the South Atlantic Anomaly (SAA), and to characterize/mitigate the background that this detector would experience. We find that Cherenkov count rates due to most particle components vary significantly depending on many different factors, including the location in the orbit and solar particle event characteristics. We also investigate the use of coincidence as a method to remove background due to trapped electrons and delta electrons, finding this method is very effective for resolving count rates due to GLEs amongst intense trapped particle environments, but some Cherenkov count rates due to trapped particles are still observed in the simulated SAA region.

This paper examines the radiation hazards posed to civil aviation by extreme space weather events, focusing on the impacts of Extreme Solar Particle Events (ESPEs) at flight altitudes. At the same time, aviation benefits from atmospheric and geomagnetic shielding, but significant residual radiation persists, particularly during the so-called Ground Level Enhancements (GLEs), with implications for both aircrew and avionics reliability. Recent high-profile incidents, such as the Airbus A320 grounding due to cosmic-ray-induced Single Event Upsets (SEUs), underscore the growing vulnerability of modern aircraft systems. The study first assessed the spectral models of GLEs and historical ESPEs to establish the total event fluence and peak event flux spectra for a selection of the strongest events. These spectra were then used as inputs to the MAIRE+ model to generate the enhanced in-flight radiation doses and SEU rates above the normal GCR values. The impact of a Carrington-type geomagnetic storm has also been assessed and analyzed. Further, the ongoing efforts to standardize aviation radiation protection are discussed, and a new atmospheric radiation scale is proposed, aiming to enhance operational mitigation and ensure safety in the enhanced space weather environment.

The monitoring of near-Earth space radiation has been a key component of space agencies’ strategies since their inception. The changes in these radiation fluxes, part of the broader space weather environment, originate from various sources, including high-energy protons emitted in solar particle events. These protons, with energies higher than 300 MeV, are a source of damage to satellites, space station infrastructure and personnel, and also have effects that are observed in aircraft and at ground level. Increasing the number of instruments monitoring the flux of these high-energy protons is vital for the next generation of space-based infrastructure. We present the development and characterisation of a compact Cherenkov radiation detector system for use on CubeSat missions: the high-energy proton instrument, HEPI. This detector displays particle species discrimination and has an inherent energy threshold via the Cherenkov radiation emission mechanism, enabling the system to monitor baseline levels of these high-energy protons and detect surges in the flux. The design of the detector as an instrument to be implemented in a multitude of small-volume satellite missions is presented, alongside the response of HEPI to electrons, galactic cosmic ray muons and protons produced at a beam facility.

Cherenkov detectors have been used in space missions for many decades, and for a variety of purposes, including for example, for Galactic Cosmic Ray (GCR) and Solar Energetic Particle (SEP) measurements. Cherenkov detectors are sensitive to many types of particles that are present in the environment of space, including gamma rays, trapped particles and cosmic particles, and each particle component acts as essentially a background when trying to view another specific particle component. In this research, GRAS/Geant4 simulations were performed to characterise the count rates that a simple Cherenkov detector design would experience in a low Earth orbit, and we find that Cherenkov count rates due to most particle components vary significantly depending on many different factors, including the location in the orbit, the date of the orbit, whether or not the detector is within the van Allen belts, and whether or not a solar particle event is occurring. We find that a small Cherenkov detector is readily able to gather detailed data on both trapped particles and spectral information during Ground-Level Enhancements. We also investigate the use of coincidence as a method to remove count rates due to trapped particles and delta electrons, finding that this method is generally very effective for resolving count rates due to GLEs amongst intense trapped particle environments, but that some Cherenkov count rates due to trapped particles are still observed in the simulated south Atlantic anomaly region.

Current space tourism ventures focus on three specific areas: long duration very high-altitude flights; also referred to as ‘near space’ flights, sub-orbital flights and visits to Low Earth Orbit (LEO). In the forthcoming decades, space travel is expected to become as commonplace as transatlantic flights. Consequently, it becomes crucial to consider the potential health implications of cosmic radiation exposure during these commercial ventures, particularly in light of sudden changes in space weather, such as ground-level enhancements (GLEs) or solar particle events (SPEs), which can have profound effects on the well-being of crew members and passengers.This paper focuses on the exposure environment and associated risk assessment for very high altitude ‘near space’ flights to the stratosphere. The current probabilistic risk assessment of the hazards for such flights is severely constrained, as the necessary dose risk factor for potential radiation exposure remains undefined for prospective space tourists. Here we examine the existing terrestrial approach to deterministic and probabilistic risk assessment for radiation exposure, specifically within the civil nuclear industry, and its applicability to ‘near space’ very high-altitude flights.We propose a revised probabilistic risk assessment methodology, including a bespoke dose risk factor, for ‘near space’ flights. Furthermore, we delve into the distinctive exposure events associated with ‘near space’ flights, explore the impact of potential variations in space weather on radiation exposure, and evaluate potential dose risk factors for utilization in probabilistic risk calculations for flight participants.Plain Language Summary: An investigation into the acceptability and probability of risks associated with potential radiation exposure from flying to ‘near space’ within newly designed craft at very high altitude in the upper atmosphere above the Earth. Comparing and assessing the applicability of terrestrial nuclear industry risk assessment methodology to space tourism and the associated radiation risks.

Within the next decade it is likely that the space tourism industry will grow and the number of humans travelling into space via commercial entities such as Virgin Galactic and Blue Origin, will increase significantly. Current space tourism ventures focus on short duration sub-orbital flights and visits to Low Earth Orbit (LEO). In the next few decades, a journey into space could become as normal as a transatlantic flight. During these new commercial ventures, the effects of cosmic radiation exposure, especially during sudden changes in space weather, such as ground level enhancement (GLE) or solar particle events (SPEs), could have significant health implications for crew and passengers. Such changes in space weather could expose space tourists to radiation doses in excess of the recommended maximum 1 mSv yearly effective dose uptake for a member of the public and 20 mSv yearly effective dose limit for those working with radiation (ICRP Publication 103, 2007 [1]). Domestic legislation and regulation focussing on potential radiation exposure for space tourists is limited and largely untested; there is heavy focus on conventional risk and wider safety, with guidance stemming from regulation of commercial high-level flights, which are significantly different to space tourism enterprises. In this paper we consider the current domestic legislation and regulations adopted by the USA and the UK, as two examples of launch nations with legislation and regulation relating to space tourism activities. We acknowledge and consider feedback we have received from the UK Civil Aviation Authority (CAA) on current regulations and topics outlined in this paper. We discuss whether current legislation and regulation offers sufficient protection for space flight participants (space tourists), and whether risk is balanced appropriately between the operators who provide space tourism services and those taking part. Finally, we discuss the routes to acceptance of the radiation risks and make recommendations for legislators, regulators and operators to support them in ensuring that the risks are managed appropriately while also supporting the development of the industry.

AniMAIRE (Anisotropic Model for Atmospheric Ionising Radiation Effects) is a new model and Python toolkit for calculating radiation dose rates experienced by aircraft during anisotropic solar energetic particle events. AniMAIRE expands the physics of the MAIRE+ model such that dose rate calculations can be performed for anisotropic solar energetic particle conditions by supplying a proton or alpha particle rigidity spectrum, a pitch angle distribution, and the conditions of Earth's magnetosphere. In this paper, we describe the algorithm and top-level structure of AniMAIRE and showcase AniMAIRE's capabilities by analysing the dose rate maps that AniMAIRE produces when the time-dependent spectra and pitch angle distribution for GLE71 are inputted. We find that the dose rates AniMAIRE produces for the event fall between the dose rates produced by the WASAVIES and CRAC:DOMO models. Dose rate maps that evolve throughout the event are also shown, and it is found that each peak in the inputted pitch angle distribution generates a dose rate hotspot in each of the polar regions. AniMAIRE has been made available openly online so that it can be downloaded and run freely on local machines and so that the space weather community can easily contribute to it using Github forking.

Mojave Air & Space Port is located in Mojave, California, United States. It is at an elevation of 2,801 feet (854 m), is nearly 30 0 0 acres in size and has three runways. It is licensed by the FAA for horizontal launches of reusable spacecraft and is already a major hub for aerospace research and space enterprises, which includes potential space flights and very high altitude subsonic, supersonic, and hypersonic flights. During potential very high-altitude 'near space' space flights, the effects of cosmic radiation exposure, especially during sudden changes in space weather, such as ground level enhancement (GLE) or solar particle events (SPEs), could have significant health implications for crew and passengers. This case study examines the intricate landscape of radiation risks, regulatory challenges, licensing complexities, and approaches to risk management for very high-altitude 'near space' space flights from Mojave Air and Space Port carrying one or more paying "space flight participant" (being an individual, who is not crew, carried aboard a launch vehicle or re-entry vehicle). The study explores the specific challenges of risk assessment of very high-altitude flights, looking in detail at the risk posed by the space weather radiation environment in flight planning and execution, for both Space Port and flight operator. The study covers the 'end to end' licensing process and the regulatory considerations of space weather required for both Space Port and flight operator. Further, we look at the integration of Safety Management Systems (SMS), namely, we explore how SMS frameworks proactively identify, assess, and mitigate risks throughout the 'near space' space flight process. Further, the study presents a template for addressing the regulatory framework for flights, risk assessment, pre-flight briefings, and the flight licensing procedure. This case study offers valuable insights for Space Port and flight operators, regulators, and policymakers, contributing to the development of comprehensive safety strategies, which are crucial for safe very high-altitude 'near space' space exploration. Plain Language Summary: A case study of how the potential space weather risks can be successfully managed for very high altitude 'near space' subsonic, supersonic, and hypersonic flights from Mojave Air and Space Port, California, USA carrying one or more space flight participant(s). (c) 2024 International Association for the Advancement of Space Safety. Published by Elsevier Ltd. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )

<p>During major solar energetic particle events, radiation dose rates in Earth's atmosphere at aviation altitudes can increase by orders of magnitude relative to dose rates during quiet times in events known as Ground-Level Enhancements (GLEs). In the case of events of a scale such that they occur once every few decades, radiation dose rates could become high enough that they pose a threat to aircraft crew and electronics. It is not currently possible to predict when such an event will occur, and existing software systems are only capable of nowcasting the current atmospheric radiation dose rates using real-time data sources. However, while it is not possible to forecast when a major event will occur, it may be possible to generate forecasts for radiation dose rates once an event has been registered to have begun. The ability to provide forecasts for dose rates once a GLE has started would be vital for airlines and for pilots in any future where aircraft might be rerouted to avoid regions of high radiation, as pilots need to be able to know not just their current radiation dose rates but radiation dose rates at possible locations where their plane might be in say half an hour's time. We report on the development of a software system to do this. This 'in-progress' radiation dose rate forecasting system will be developed by integrating the FOrecasting Relativistic particles during GLE Events (FORGE) system being developed at the University of Central Lancashire with an anisotropic extension to the Models for Atmospheric Ionising Radiation Effects+ (MAIRE+) system being developed at the University of Surrey. We report on the development of both of these systems and their integration.</p>

<p>Cosmic Ray Sensors (CRS) are used worldwide to measure soil moisture at intermediate scales, exploiting the neutrons produced in the air showers created by cosmic ray particles interacting with the atmosphere. Neutron Monitors also exploit these atmospheric neutrons, but they are shielded from local soil moisture variations so that information about the cosmic ray flux near Earth can be deduced from their observations. Neutron monitors remain the state of the art for observing variations in high-energy cosmic rays and are critically important to understanding ground-level enhancements of atmospheric radiation caused by high energy solar energetic particles.</p> <p>This contribution explores how the UK CRS network (COSMOS-UK) can complement the neutron monitor network in monitoring these ground-level enhancements, as well as other space weather-driven variations in the ground-level neutron flux. Observations of such variations using COSMOS-UK are presented and discussed, and the sensitivity of COSMOS-UK to ground-level enhancements is also shown. Finally, the prospects and challenges of improving the space weather utility of CRS networks are discussed.</p>

We present data from the sister instruments Merlin and cosmic radiation environment dosimetry and charging experiment (CREDANCE), from medium Earth orbit (MEO) and the slot region, respectively. Each instrument measures internal charging current, proton and ion flux, and total ionizing dose with an identical suite of instruments. In this article, we present charging current and proton flux data. Merlin flew on board the Giove-A MEO testbed spacecraft from December 2005 to November 2021. CREDANCE flew on board the Demonstration and Science Experiments (DSX) spacecraft from July 2019 to May 2021.

Within the next decade it is likely that the space tourism industry will grow dramatically and the number of humans travelling into, and beyond, the stratosphere via commercial entities such as World View and Space Perspective will increase. Current space tourism ventures focus on long duration very high altitude balloon flights; also known as 'near space' flights, sub-orbital flights and visits to Low Earth Orbit (LEO). In the next few decades space tourism is ultimately likely to become routine. During these new commercial ventures the effects of cosmic radiation exposure, especially during sudden changes in space weather, such as ground level enhancement (GLE) events, could have significant health implications for crew and passengers. The risks from these rapid changes in space weather and potential radiation exposure during flights is not currently fully understood or even acknowledged. Legislation and regulation for such enterprises is also in its infancy with little or no guidance for commercial entities or potential passengers. Initial work at the University of Surrey has focused on very high altitude 'near space' balloon flights. World-wide launch locations for flights have been modelled using MAIRE and CARI-7 computer programs. Flight routes have been monitored, for current commercial and higher flight levels, using the Smart Atmospheric Ionizing Radiation (SAIRA) detector. The modelled flight profiles have been compared with detector data, up to a maximum flight altitude of 30 km (10 0,0 0 0 ft), with varying space weather conditions, from norms to extreme events, to assess the radiation risk presented by potential exposure.Plain Language Summary: An assessment of the risks and potential radiation exposure from flying to 'near space' within newly designed observation balloons at very high altitude in the upper atmosphere above the Earth. Looking at the impact of radiation from the sun and sources outside the solar system, and critically when these conditions vary which could result in high levels of exposure.(c) 2023 International Association for the Advancement of Space Safety. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )

The objectives, instrumentation, methods, and data leading up to launch of the NASA Living With a Star (LWS) Space Environment Testbed (SET) payload onboard the Air Force Research Laboratory Demonstration and Science Experiments (DSX) spacecraft are described. The experiments characterize the space radiation environment and how it affects the hardware performance. The payload consists of a compact space weather instrument and a carrier containing four board experiments.

The Environmental Monitoring Units (EMU), on-board two satellites of the EU Galileo constellation, monitor the radiation environment along the GNSS orbit providing measurements of the energetic electron fluxes in the outer Van Allen Belt. With new calibration studies that take into account more realistic shielding provided by the spacecraft and the characteristics of the encountered environment along the satellite orbit, we have derived a new version of the GSAT/EMU Level 1 dataset that provides high quality validated fluxes of trapped energetic electrons within the 0.2-4.5 MeV energy range. In this work, we present an overview of the EMU measured electron fluxes over the last five years including recently completed validation studies with Arase [ERG] and RBSP energetic electron measurements. The new dataset, available to users from European member states registered at https://gssc.esa.int, will be used in the assimilation processes and/or the validation of the ONERA Salammbô electron radiation belt models - under the EU Safespace activity and ESA S2P RBFAN activity - leading to improved forecasts of the state of the outer belt. In addition, the quality of the time-coverage of the dataset permits their use in the development and/or evaluation of quantitative radiation environment specification models. This work has received funding from the European Union’s Horizon 2020 research and innovation programme "SafeSpace" under grant agreement No 870437, from the European Space Agency activity "Cross Calibration EMU Dataset with RBSP" under ESA Contract 4000135823/21/NL/GLC/mkn and the “SSA P3-SWE-X Space Environment Nowcast and Forecast Development” activity under ESA Contract 4000131381/20/D/CT.

This paper summarizes observations of micro-SEL phenomena during the SEU testing of sub 100 nm COTS SRAMs with an accelerated atmospheric neutron spectra. SEU statistics are compared with historic data to demonstrate there is not a potential SEU increased susceptibility for modern COTS SRAMs however the static test method may have displayed characteristics i.e. micro-latches that may not be visible from a pseudo-static test. The SEU cross sections demonstrates the essential requirement to continue to test SRAMs for their responses to atmospheric neutrons particularly those which will be used within critical applications e.g. flight avionics.

Abstract Significant increases to the atmospheric radiation environment are recorded by a network of ground level neutron monitors as ground level enhancements (GLEs). These space weather phenomena pose a risk to aviation via single event effects in aircraft electronics and ionizing dose to passengers and crew. Under the UK Space Weather Instrumentation, Measurement, Modeling and Risk programme, we have developed a new model to provide nowcasts of the aviation radiation environment, including both the galactic cosmic ray (GCR) background and during GLE events. The Model for Atmospheric Ionising Radiation Effects (MAIRE+) uses multiple data sources to characterize primary GCR and GLE particle spectra and combines these with precalculated geomagnetic and atmospheric response matrices to predict particle fluxes from ground level to 20 km altitude across the entire globe. Two European neutron monitors (located at Oulu in Finland and Dourbes in Belgium) are used as the primary indicators of GLE intensity in order to maximize accuracy over UK airspace. Outputs from MAIRE+ for the historical GLEs in September and October 1989 are compared to recalibrated empirical data from a solid‐state detector that was carried on Concorde in that period. The model will be hosted in the UK and will provide additional capability to the Met Office Space Weather Operations Center (MOSWOC).

The geographic structure of radiation dose rates at aircraft altitudes in Earth's atmosphere during the irradiation of Earth by proton spectra from incoming solar particle events is examined using the recently developed MAIRE+ software. Conditions are examined under two incoming proton spectra, a low/hard spectral index and a high/soft spectral index spectra, which are representative of some of the solar particle events that have caused reasonably sized Ground-Level Enhancements/Events (GLEs) over the past 70 years. It is found through the use of `cut-throughs' of the atmosphere, that the atmosphere can be divided into three volumes; a high dose rate polar region, a low dose rate equatorial region, and a transition region between the two. The location of these regions as a function of latitude, longitude and altitude is characterised. It is also found that the location of the transition region changes for different magnetospheric disturbance levels, implying that the total radiation dose rate an aircraft will experience if it passes through the transition region will be subject to large systematic uncertainties, particularly during the currently unknown levels of magnetospheric disturbance that a major solar event could cause. The impact that various magnetospheric conditions might have on dose rates that specific flight routes might experience is also discussed.