The NASA Radiation Dosimetry Experiment (RaD‐X) stratospheric balloon flight mission obtained measurements for improving the understanding of cosmic radiation transport in the atmosphere and human exposure to this ionizing radiation field in the aircraft environment. The value of dosimetric measurements from the balloon platform is that they can be used to characterize cosmic ray primaries, the ultimate source of aviation radiation exposure. In addition, radiation detectors were flown to assess their potential application to long‐term, continuous monitoring of the aircraft radiation environment. The RaD‐X balloon was successfully launched from Fort Sumner, New Mexico (34.5°N, 104.2°W) on 25 September 2015. Over 18 h of flight data were obtained from each of the four different science instruments at altitudes above 20 km. The RaD‐X balloon flight was supplemented by contemporaneous aircraft measurements. Flight‐averaged dosimetric quantities are reported at seven altitudes to provide benchmark measurements for improving aviation radiation models. The altitude range of the flight data extends from commercial aircraft altitudes to above the Pfotzer maximum where the dosimetric quantities are influenced by cosmic ray primaries. The RaD‐X balloon flight observed an absence of the Pfotzer maximum in the measurements of dose equivalent rate.
The Automated Radiation Measurements for Aerospace Safety (ARMAS) program has successfully deployed a fleet of six instruments measuring the ambient radiation environment at commercial aircraft altitudes. ARMAS transmits real‐time data to the ground and provides quality, tissue‐relevant ambient dose equivalent rates with 5 min latency for dose rates on 213 flights up to 17.3 km (56,700 ft). We show five cases from different aircraft; the source particles are dominated by galactic cosmic rays but include particle fluxes for minor radiation periods and geomagnetically disturbed conditions. The measurements from 2013 to 2016 do not cover a period of time to quantify galactic cosmic rays' dependence on solar cycle variation and their effect on aviation radiation. However, we report on small radiation “clouds” in specific magnetic latitude regions and note that active geomagnetic, variable space weather conditions may sufficiently modify the magnetospheric magnetic field that can enhance the radiation environment, particularly at high altitudes and middle to high latitudes. When there is no significant space weather, high‐latitude flights produce a dose rate analogous to a chest X‐ray every 12.5 h, every 25 h for midlatitudes, and every 100 h for equatorial latitudes at typical commercial flight altitudes of 37,000 ft (~11 km). The dose rate doubles every 2 km altitude increase, suggesting a radiation event management strategy for pilots or air traffic control; i.e., where event‐driven radiation regions can be identified, they can be treated like volcanic ash clouds to achieve radiation safety goals with slightly lower flight altitudes or more equatorial flight paths.
Results are presented from evaluations of radiation dosimeters prior to a NASA high‐altitude balloon flight, the RaD‐X mission. Four radiation dosimeters were on board RaD‐X: a Far West Hawk (version 3), a Teledyne dosimeter (UDOS001), a Liulin dosimeter (MDU 6SA1), and a RaySure dosimeter (version 3b). The Hawk is a tissue‐equivalent proportional counter (TEPC) and the others are solid‐state Si sensors. The Hawk served as the “flight standard” and was calibrated for this mission. The Si‐based dosimeters were tested to make sure they functioned properly prior to flight but were not calibrated for the radiation environment in the stratosphere. The dosimeters were exposed to 60Co gamma rays and 252Cf fission radiation (which includes both neutrons and gamma rays) at the Lawrence Livermore National Laboratory (LLNL). The measurement results were compared with results from standard “benchmark” measurements of the same sources and source‐to‐detector distances performed contemporaneously by LLNL calibration facility personnel. For 60Co gamma rays, the dosimeter‐to‐benchmark ratios were 0.84 ± 0.06, 1.07 ± 0.32, 1.31 ± 0.07, and 0.82 ± 0.24 for the TEPC, Teledyne, Liulin, and RaySure, respectively. For 252Cf radiation, the dosimeter‐to‐benchmark ratios were 0.94 ± 0.15, 0.55 ± 0.18, 0.58 ± 0.08, and 0.33 ± 0.12 for the TEPC, Teledyne, Liulin, and RaySure. Some examples of how the results were used to help interpret the flight data are also presented.
Air safety is tied to the phenomenon of ionizing radiation from space weather, primarily from galactic cosmic rays but also from solar energetic particles. A global framework for addressing radiation issues in this environment has been constructed, but more must be done at international and national levels. Health consequences from atmospheric radiation exposure are likely to exist. In addition, severe solar radiation events may cause economic consequences in the international aviation community due to exposure limits being reached by some crew members. Impacts from a radiation environment upon avionics from high-energy particles and low-energy, thermalized neutrons are now recognized as an area of active interest. A broad community recognizes that there are a number of mitigation paths that can be taken relative to the human tissue and avionics exposure risks. These include developing active monitoring and measurement programs as well as improving scientific modeling capabilities that can eventually be turned into operations. A number of roadblocks to risk mitigation still exist, such as effective pilot training programs as well as monitoring, measuring, and regulatory measures. An active international effort toward observing the weather of atmospheric radiation must occur to make progress in mitigating radiation exposure risks. Stakeholders in this process include standard-making bodies, scientific organizations, regulatory organizations, air traffic management systems, aircraft owners and operators, pilots and crew, and even the public. Aviation Radiation Is an Unavoidable Space Weather PhenomenonAir safety has improved significantly in many meteorological areas over the past decades with the exception of space weather, which includes ionizing radiation. While a framework for addressing radiation issues has been constructed, we believe that more can and must be done at international and national levels. In particular, measurement programs must be expanded and linked with models to provide current epoch and, eventually, forecast information for the aviation ionizing radiation environment. A diverse radiation measurement and modeling community exists with a strong interest in improving international air safety.There are two challenges in our ever more mobile, technologically dependent global society. First, pilots, crew, and passengers, which include fetuses between their first and second trimesters, might face additional radiation hazards in terms of dose equivalent rate (rate of absorbed dose multiplied by the quality factor), particularly when flying at commercial aviation altitudes above 26,000 ft. (7924.8 m) (8 km) (see Figure 1). Second, avionics can experience single event effects (SEEs) from both the ambient high-energy and thermal neutron environments. The source of this radiation in either case is twofold-from the continuous bombardment by primary background galactic cosmic rays (GCRs) and also from solar energetic particles (SEPs) emitted during occasional solar flare events lasting up to a ...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.